physical bullying research paper

Preventing Bullying Through Science, Policy, and Practice (2016)

Chapter: 1 introduction, 1 introduction.

Bullying, long tolerated by many as a rite of passage into adulthood, is now recognized as a major and preventable public health problem, one that can have long-lasting consequences ( McDougall and Vaillancourt, 2015 ; Wolke and Lereya, 2015 ). Those consequences—for those who are bullied, for the perpetrators of bullying, and for witnesses who are present during a bullying event—include poor school performance, anxiety, depression, and future delinquent and aggressive behavior. Federal, state, and local governments have responded by adopting laws and implementing programs to prevent bullying and deal with its consequences. However, many of these responses have been undertaken with little attention to what is known about bullying and its effects. Even the definition of bullying varies among both researchers and lawmakers, though it generally includes physical and verbal behavior, behavior leading to social isolation, and behavior that uses digital communications technology (cyberbullying). This report adopts the term “bullying behavior,” which is frequently used in the research field, to cover all of these behaviors.

Bullying behavior is evident as early as preschool, although it peaks during the middle school years ( Currie et al., 2012 ; Vaillancourt et al., 2010 ). It can occur in diverse social settings, including classrooms, school gyms and cafeterias, on school buses, and online. Bullying behavior affects not only the children and youth who are bullied, who bully, and who are both bullied and bully others but also bystanders to bullying incidents. Given the myriad situations in which bullying can occur and the many people who may be involved, identifying effective prevention programs and policies is challenging, and it is unlikely that any one approach will be ap-

propriate in all situations. Commonly used bullying prevention approaches include policies regarding acceptable behavior in schools and behavioral interventions to promote positive cultural norms.

STUDY CHARGE

Recognizing that bullying behavior is a major public health problem that demands the concerted and coordinated time and attention of parents, educators and school administrators, health care providers, policy makers, families, and others concerned with the care of children, a group of federal agencies and private foundations asked the National Academies of Sciences, Engineering, and Medicine to undertake a study of what is known and what needs to be known to further the field of preventing bullying behavior. The Committee on the Biological and Psychosocial Effects of Peer Victimization:

Lessons for Bullying Prevention was created to carry out this task under the Academies’ Board on Children, Youth, and Families and the Committee on Law and Justice. The study received financial support from the Centers for Disease Control and Prevention (CDC), the Eunice Kennedy Shriver National Institute of Child Health and Human Development, the Health Resources and Services Administration, the Highmark Foundation, the National Institute of Justice, the Robert Wood Johnson Foundation, Semi J. and Ruth W. Begun Foundation, and the Substance Abuse and Mental Health Services Administration. The full statement of task for the committee is presented in Box 1-1 .

Although the committee acknowledges the importance of this topic as it pertains to all children in the United States and in U.S. territories, this report focuses on the 50 states and the District of Columbia. Also, while the committee acknowledges that bullying behavior occurs in the school

environment for youth in foster care, in juvenile justice facilities, and in other residential treatment facilities, this report does not address bullying behavior in those environments because it is beyond the study charge.

CONTEXT FOR THE STUDY

This section of the report highlights relevant work in the field and, later in the chapter under “The Committee’s Approach,” presents the conceptual framework and corresponding definitions of terms that the committee has adopted.

Historical Context

Bullying behavior was first characterized in the scientific literature as part of the childhood experience more than 100 years ago in “Teasing and Bullying,” published in the Pedagogical Seminary ( Burk, 1897 ). The author described bullying behavior, attempted to delineate causes and cures for the tormenting of others, and called for additional research ( Koo, 2007 ). Nearly a century later, Dan Olweus, a Swedish research professor of psychology in Norway, conducted an intensive study on bullying ( Olweus, 1978 ). The efforts of Olweus brought awareness to the issue and motivated other professionals to conduct their own research, thereby expanding and contributing to knowledge of bullying behavior. Since Olweus’s early work, research on bullying has steadily increased (see Farrington and Ttofi, 2009 ; Hymel and Swearer, 2015 ).

Over the past few decades, venues where bullying behavior occurs have expanded with the advent of the Internet, chat rooms, instant messaging, social media, and other forms of digital electronic communication. These modes of communication have provided a new communal avenue for bullying. While the media reports linking bullying to suicide suggest a causal relationship, the available research suggests that there are often multiple factors that contribute to a youth’s suicide-related ideology and behavior. Several studies, however, have demonstrated an association between bullying involvement and suicide-related ideology and behavior (see, e.g., Holt et al., 2015 ; Kim and Leventhal, 2008 ; Sourander, 2010 ; van Geel et al., 2014 ).

In 2013, the Health Resources and Services Administration of the U.S. Department of Health and Human Services requested that the Institute of Medicine 1 and the National Research Council convene an ad hoc planning committee to plan and conduct a 2-day public workshop to highlight relevant information and knowledge that could inform a multidisciplinary

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1 Prior to 2015, the National Academy of Medicine was known as the Institute of Medicine.

road map on next steps for the field of bullying prevention. Content areas that were explored during the April 2014 workshop included the identification of conceptual models and interventions that have proven effective in decreasing bullying and the antecedents to bullying while increasing protective factors that mitigate the negative health impact of bullying. The discussions highlighted the need for a better understanding of the effectiveness of program interventions in realistic settings; the importance of understanding what works for whom and under what circumstances, as well as the influence of different mediators (i.e., what accounts for associations between variables) and moderators (i.e., what affects the direction or strength of associations between variables) in bullying prevention efforts; and the need for coordination among agencies to prevent and respond to bullying. The workshop summary ( Institute of Medicine and National Research Council, 2014c ) informs this committee’s work.

Federal Efforts to Address Bullying and Related Topics

Currently, there is no comprehensive federal statute that explicitly prohibits bullying among children and adolescents, including cyberbullying. However, in the wake of the growing concerns surrounding the implications of bullying, several federal initiatives do address bullying among children and adolescents, and although some of them do not primarily focus on bullying, they permit some funds to be used for bullying prevention purposes.

The earliest federal initiative was in 1999, when three agencies collaborated to establish the Safe Schools/Healthy Students initiative in response to a series of deadly school shootings in the late 1990s. The program is administered by the U.S. Departments of Education, Health and Human Services, and Justice to prevent youth violence and promote the healthy development of youth. It is jointly funded by the Department of Education and by the Department of Health and Human Services’ Substance Abuse and Mental Health Services Administration. The program has provided grantees with both the opportunity to benefit from collaboration and the tools to sustain it through deliberate planning, more cost-effective service delivery, and a broader funding base ( Substance Abuse and Mental Health Services Administration, 2015 ).

The next major effort was in 2010, when the Department of Education awarded $38.8 million in grants under the Safe and Supportive Schools (S3) Program to 11 states to support statewide measurement of conditions for learning and targeted programmatic interventions to improve conditions for learning, in order to help schools improve safety and reduce substance use. The S3 Program was administered by the Safe and Supportive Schools Group, which also administered the Safe and Drug-Free Schools and Communities Act State and Local Grants Program, authorized by the

1994 Elementary and Secondary Education Act. 2 It was one of several programs related to developing and maintaining safe, disciplined, and drug-free schools. In addition to the S3 grants program, the group administered a number of interagency agreements with a focus on (but not limited to) bullying, school recovery research, data collection, and drug and violence prevention activities ( U.S. Department of Education, 2015 ).

A collaborative effort among the U.S. Departments of Agriculture, Defense, Education, Health and Human Services, Interior, and Justice; the Federal Trade Commission; and the White House Initiative on Asian Americans and Pacific Islanders created the Federal Partners in Bullying Prevention (FPBP) Steering Committee. Led by the U.S. Department of Education, the FPBP works to coordinate policy, research, and communications on bullying topics. The FPBP Website provides extensive resources on bullying behavior, including information on what bullying is, its risk factors, its warning signs, and its effects. 3 The FPBP Steering Committee also plans to provide details on how to get help for those who have been bullied. It also was involved in creating the “Be More than a Bystander” Public Service Announcement campaign with the Ad Council to engage students in bullying prevention. To improve school climate and reduce rates of bullying nationwide, FPBP has sponsored four bullying prevention summits attended by education practitioners, policy makers, researchers, and federal officials.

In 2014, the National Institute of Justice—the scientific research arm of the U.S. Department of Justice—launched the Comprehensive School Safety Initiative with a congressional appropriation of $75 million. The funds are to be used for rigorous research to produce practical knowledge that can improve the safety of schools and students, including bullying prevention. The initiative is carried out through partnerships among researchers, educators, and other stakeholders, including law enforcement, behavioral and mental health professionals, courts, and other justice system professionals ( National Institute of Justice, 2015 ).

In 2015, the Every Student Succeeds Act was signed by President Obama, reauthorizing the 50-year-old Elementary and Secondary Education Act, which is committed to providing equal opportunities for all students. Although bullying is neither defined nor prohibited in this act, it is explicitly mentioned in regard to applicability of safe school funding, which it had not been in previous iterations of the Elementary and Secondary Education Act.

The above are examples of federal initiatives aimed at promoting the

2 The Safe and Drug-Free Schools and Communities Act was included as Title IV, Part A, of the 1994 Elementary and Secondary Education Act. See http://www.ojjdp.gov/pubs/gun_violence/sect08-i.html [October 2015].

3 For details, see http://www.stopbullying.gov/ [October 2015].

healthy development of youth, improving the safety of schools and students, and reducing rates of bullying behavior. There are several other federal initiatives that address student bullying directly or allow funds to be used for bullying prevention activities.

Definitional Context

The terms “bullying,” “harassment,” and “peer victimization” have been used in the scientific literature to refer to behavior that is aggressive, is carried out repeatedly and over time, and occurs in an interpersonal relationship where a power imbalance exists ( Eisenberg and Aalsma, 2005 ). Although some of these terms have been used interchangeably in the literature, peer victimization is targeted aggressive behavior of one child against another that causes physical, emotional, social, or psychological harm. While conflict and bullying among siblings are important in their own right ( Tanrikulu and Campbell, 2015 ), this area falls outside of the scope of the committee’s charge. Sibling conflict and aggression falls under the broader concept of interpersonal aggression, which includes dating violence, sexual assault, and sibling violence, in addition to bullying as defined for this report. Olweus (1993) noted that bullying, unlike other forms of peer victimization where the children involved are equally matched, involves a power imbalance between the perpetrator and the target, where the target has difficulty defending him or herself and feels helpless against the aggressor. This power imbalance is typically considered a defining feature of bullying, which distinguishes this particular form of aggression from other forms, and is typically repeated in multiple bullying incidents involving the same individuals over time ( Olweus, 1993 ).

Bullying and violence are subcategories of aggressive behavior that overlap ( Olweus, 1996 ). There are situations in which violence is used in the context of bullying. However, not all forms of bullying (e.g., rumor spreading) involve violent behavior. The committee also acknowledges that perspective about intentions can matter and that in many situations, there may be at least two plausible perceptions involved in the bullying behavior.

A number of factors may influence one’s perception of the term “bullying” ( Smith and Monks, 2008 ). Children and adolescents’ understanding of the term “bullying” may be subject to cultural interpretations or translations of the term ( Hopkins et al., 2013 ). Studies have also shown that influences on children’s understanding of bullying include the child’s experiences as he or she matures and whether the child witnesses the bullying behavior of others ( Hellström et al., 2015 ; Monks and Smith, 2006 ; Smith and Monks, 2008 ).

In 2010, the FPBP Steering Committee convened its first summit, which brought together more than 150 nonprofit and corporate leaders,

researchers, practitioners, parents, and youths to identify challenges in bullying prevention. Discussions at the summit revealed inconsistencies in the definition of bullying behavior and the need to create a uniform definition of bullying. Subsequently, a review of the 2011 CDC publication of assessment tools used to measure bullying among youth ( Hamburger et al., 2011 ) revealed inconsistent definitions of bullying and diverse measurement strategies. Those inconsistencies and diverse measurements make it difficult to compare the prevalence of bullying across studies ( Vivolo et al., 2011 ) and complicate the task of distinguishing bullying from other types of aggression between youths. A uniform definition can support the consistent tracking of bullying behavior over time, facilitate the comparison of bullying prevalence rates and associated risk and protective factors across different data collection systems, and enable the collection of comparable information on the performance of bullying intervention and prevention programs across contexts ( Gladden et al., 2014 ). The CDC and U.S. Department of Education collaborated on the creation of the following uniform definition of bullying (quoted in Gladden et al., 2014, p. 7 ):

Bullying is any unwanted aggressive behavior(s) by another youth or group of youths who are not siblings or current dating partners that involves an observed or perceived power imbalance and is repeated multiple times or is highly likely to be repeated. Bullying may inflict harm or distress on the targeted youth including physical, psychological, social, or educational harm.

This report noted that the definition includes school-age individuals ages 5-18 and explicitly excludes sibling violence and violence that occurs in the context of a dating or intimate relationship ( Gladden et al., 2014 ). This definition also highlighted that there are direct and indirect modes of bullying, as well as different types of bullying. Direct bullying involves “aggressive behavior(s) that occur in the presence of the targeted youth”; indirect bullying includes “aggressive behavior(s) that are not directly communicated to the targeted youth” ( Gladden et al., 2014, p. 7 ). The direct forms of violence (e.g., sibling violence, teen dating violence, intimate partner violence) can include aggression that is physical, sexual, or psychological, but the context and uniquely dynamic nature of the relationship between the target and the perpetrator in which these acts occur is different from that of peer bullying. Examples of direct bullying include pushing, hitting, verbal taunting, or direct written communication. A common form of indirect bullying is spreading rumors. Four different types of bullying are commonly identified—physical, verbal, relational, and damage to property. Some observational studies have shown that the different forms of bullying that youths commonly experience may overlap ( Bradshaw et al., 2015 ;

Godleski et al., 2015 ). The four types of bullying are defined as follows ( Gladden et al., 2014 ):

• Physical bullying involves the use of physical force (e.g., shoving, hitting, spitting, pushing, and tripping).
• Verbal bullying involves oral or written communication that causes harm (e.g., taunting, name calling, offensive notes or hand gestures, verbal threats).
• Relational bullying is behavior “designed to harm the reputation and relationships of the targeted youth (e.g., social isolation, rumor spreading, posting derogatory comments or pictures online).”
• Damage to property is “theft, alteration, or damaging of the target youth’s property by the perpetrator to cause harm.”

In recent years, a new form of aggression or bullying has emerged, labeled “cyberbullying,” in which the aggression occurs through modern technological devices, specifically mobile phones or the Internet ( Slonje and Smith, 2008 ). Cyberbullying may take the form of mean or nasty messages or comments, rumor spreading through posts or creation of groups, and exclusion by groups of peers online.

While the CDC definition identifies bullying that occurs using technology as electronic bullying and views that as a context or location where bullying occurs, one of the major challenges in the field is how to conceptualize and define cyberbullying ( Tokunaga, 2010 ). The extent to which the CDC definition can be applied to cyberbullying is unclear, particularly with respect to several key concepts within the CDC definition. First, whether determination of an interaction as “wanted” or “unwanted” or whether communication was intended to be harmful can be challenging to assess in the absence of important in-person socioemotional cues (e.g., vocal tone, facial expressions). Second, assessing “repetition” is challenging in that a single harmful act on the Internet has the potential to be shared or viewed multiple times ( Sticca and Perren, 2013 ). Third, cyberbullying can involve a less powerful peer using technological tools to bully a peer who is perceived to have more power. In this manner, technology may provide the tools that create a power imbalance, in contrast to traditional bullying, which typically involves an existing power imbalance.

A study that used focus groups with college students to discuss whether the CDC definition applied to cyberbullying found that students were wary of applying the definition due to their perception that cyberbullying often involves less emphasis on aggression, intention, and repetition than other forms of bullying ( Kota et al., 2014 ). Many researchers have responded to this lack of conceptual and definitional clarity by creating their own measures to assess cyberbullying. It is noteworthy that very few of these

definitions and measures include the components of traditional bullying—i.e., repetition, power imbalance, and intent ( Berne et al., 2013 ). A more recent study argues that the term “cyberbullying” should be reserved for incidents that involve key aspects of bullying such as repetition and differential power ( Ybarra et al., 2014 ).

Although the formulation of a uniform definition of bullying appears to be a step in the right direction for the field of bullying prevention, there are some limitations of the CDC definition. For example, some researchers find the focus on school-age youth as well as the repeated nature of bullying to be rather limiting; similarly the exclusion of bullying in the context of sibling relationships or dating relationships may preclude full appreciation of the range of aggressive behaviors that may co-occur with or constitute bullying behavior. As noted above, other researchers have raised concerns about whether cyberbullying should be considered a particular form or mode under the broader heading of bullying as suggested in the CDC definition, or whether a separate defintion is needed. Furthermore, the measurement of bullying prevalence using such a definiton of bullying is rather complex and does not lend itself well to large-scale survey research. The CDC definition was intended to inform public health surveillance efforts, rather than to serve as a definition for policy. However, increased alignment between bullying definitions used by policy makers and researchers would greatly advance the field. Much of the extant research on bullying has not applied a consistent definition or one that aligns with the CDC definition. As a result of these and other challenges to the CDC definition, thus far there has been inconsistent adoption of this particular definition by researchers, practitioners, or policy makers; however, as the definition was created in 2014, less than 2 years is not a sufficient amount of time to assess whether it has been successfully adopted or will be in the future.

THE COMMITTEE’S APPROACH

This report builds on the April 2014 workshop, summarized in Building Capacity to Reduce Bullying: Workshop Summary ( Institute of Medicine and National Research Council, 2014c ). The committee’s work was accomplished over an 18-month period that began in October 2014, after the workshop was held and the formal summary of it had been released. The study committee members represented expertise in communication technology, criminology, developmental and clinical psychology, education, mental health, neurobiological development, pediatrics, public health, school administration, school district policy, and state law and policy. (See Appendix E for biographical sketches of the committee members and staff.) The committee met three times in person and conducted other meetings by teleconferences and electronic communication.

Information Gathering

The committee conducted an extensive review of the literature pertaining to peer victimization and bullying. In some instances, the committee drew upon the broader literature on aggression and violence. The review began with an English-language literature search of online databases, including ERIC, Google Scholar, Lexis Law Reviews Database, Medline, PubMed, Scopus, PsycInfo, and Web of Science, and was expanded as literature and resources from other countries were identified by committee members and project staff as relevant. The committee drew upon the early childhood literature since there is substantial evidence indicating that bullying involvement happens as early as preschool (see Vlachou et al., 2011 ). The committee also drew on the literature on late adolescence and looked at related areas of research such as maltreatment for insights into this emerging field.

The committee used a variety of sources to supplement its review of the literature. The committee held two public information-gathering sessions, one with the study sponsors and the second with experts on the neurobiology of bullying; bullying as a group phenomenon and the role of bystanders; the role of media in bullying prevention; and the intersection of social science, the law, and bullying and peer victimization. See Appendix A for the agendas for these two sessions. To explore different facets of bullying and give perspectives from the field, a subgroup of the committee and study staff also conducted a site visit to a northeastern city, where they convened four stakeholder groups comprised, respectively, of local practitioners, school personnel, private foundation representatives, and young adults. The site visit provided the committee with an opportunity for place-based learning about bullying prevention programs and best practices. Each focus group was transcribed and summarized thematically in accordance with this report’s chapter considerations. Themes related to the chapters are displayed throughout the report in boxes titled “Perspectives from the Field”; these boxes reflect responses synthesized from all four focus groups. See Appendix B for the site visit’s agenda and for summaries of the focus groups.

The committee also benefited from earlier reports by the National Academies of Sciences, Engineering, and Medicine through its Division of Behavioral and Social Sciences and Education and the Institute of Medicine, most notably:

• Reducing Risks for Mental Disorders: Frontiers for Preventive Intervention Research ( Institute of Medicine, 1994 )
• Community Programs to Promote Youth Development ( National Research Council and Institute of Medicine, 2002 )
• Deadly Lessons: Understanding Lethal School Violence ( National Research Council and Institute of Medicine, 2003 )
• Preventing Mental, Emotional, and Behavioral Disorders Among Young People: Progress and Possibilities ( National Research Council and Institute of Medicine, 2009 )
• The Science of Adolescent Risk-Taking: Workshop Report ( Institute of Medicine and National Research Council, 2011 )
• Communications and Technology for Violence Prevention: Workshop Summary ( Institute of Medicine and National Research Council, 2012 )
• Building Capacity to Reduce Bullying: Workshop Summary ( Institute of Medicine and National Research Council, 2014c )
• The Evidence for Violence Prevention across the Lifespan and Around the World: Workshop Summary ( Institute of Medicine and National Research Council, 2014a )
• Strategies for Scaling Effective Family-Focused Preventive Interventions to Promote Children’s Cognitive, Affective, and Behavioral Health: Workshop Summary ( Institute of Medicine and National Research Council, 2014b )
• Investing in the Health and Well-Being of Young Adults ( Institute of Medicine and National Research Council, 2015 )

Although these past reports and workshop summaries address various forms of violence and victimization, this report is the first consensus study by the National Academies of Sciences, Engineering, and Medicine on the state of the science on the biological and psychosocial consequences of bullying and the risk and protective factors that either increase or decrease bullying behavior and its consequences.

Terminology

Given the variable use of the terms “bullying” and “peer victimization” in both the research-based and practice-based literature, the committee chose to use the current CDC definition quoted above ( Gladden et al., 2014, p. 7 ). While the committee determined that this was the best definition to use, it acknowledges that this definition is not necessarily the most user-friendly definition for students and has the potential to cause problems for students reporting bullying. Not only does this definition provide detail on the common elements of bullying behavior but it also was developed with input from a panel of researchers and practitioners. The committee also followed the CDC in focusing primarily on individuals between the ages of 5 and 18. The committee recognizes that children’s development occurs on a continuum, and so while it relied primarily on the CDC defini-

tion, its work and this report acknowledge the importance of addressing bullying in both early childhood and emerging adulthood. For purposes of this report, the committee used the terms “early childhood” to refer to ages 1-4, “middle childhood” for ages 5 to 10, “early adolescence” for ages 11-14, “middle adolescence” for ages 15-17, and “late adolescence” for ages 18-21. This terminology and the associated age ranges are consistent with the Bright Futures and American Academy of Pediatrics definition of the stages of development. 4

A given instance of bullying behavior involves at least two unequal roles: one or more individuals who perpetrate the behavior (the perpetrator in this instance) and at least one individual who is bullied (the target in this instance). To avoid labeling and potentially further stigmatizing individuals with the terms “bully” and “victim,” which are sometimes viewed as traits of persons rather than role descriptions in a particular instance of behavior, the committee decided to use “individual who is bullied” to refer to the target of a bullying instance or pattern and “individual who bullies” to refer to the perpetrator of a bullying instance or pattern. Thus, “individual who is bullied and bullies others” can refer to one who is either perpetrating a bullying behavior or a target of bullying behavior, depending on the incident. This terminology is consistent with the approach used by the FPBP (see above). Also, bullying is a dynamic social interaction ( Espelage and Swearer, 2003 ) where individuals can play different roles in bullying interactions based on both individual and contextual factors.

The committee used “cyberbullying” to refer to bullying that takes place using technology or digital electronic means. “Digital electronic forms of contact” comprise a broad category that may include e-mail, blogs, social networking Websites, online games, chat rooms, forums, instant messaging, Skype, text messaging, and mobile phone pictures. The committee uses the term “traditional bullying” to refer to bullying behavior that is not cyberbullying (to aid in comparisons), recognizing that the term has been used at times in slightly different senses in the literature.

Where accurate reporting of study findings requires use of the above terms but with senses different from those specified here, the committee has noted the sense in which the source used the term. Similarly, accurate reporting has at times required use of terms such as “victimization” or “victim” that the committee has chosen to avoid in its own statements.

4 For details on these stages of adolescence, see https://brightfutures.aap.org/Bright%20Futures%20Documents/3-Promoting_Child_Development.pdf [October 2015].

ORGANIZATION OF THE REPORT

This report is organized into seven chapters. After this introductory chapter, Chapter 2 provides a broad overview of the scope of the problem.

Chapter 3 focuses on the conceptual frameworks for the study and the developmental trajectory of the child who is bullied, the child who bullies, and the child who is bullied and also bullies. It explores processes that can explain heterogeneity in bullying outcomes by focusing on contextual processes that moderate the effect of individual characteristics on bullying behavior.

Chapter 4 discusses the cyclical nature of bullying and the consequences of bullying behavior. It summarizes what is known about the psychosocial, physical health, neurobiological, academic-performance, and population-level consequences of bullying.

Chapter 5 provides an overview of the landscape in bullying prevention programming. This chapter describes in detail the context for preventive interventions and the specific actions that various stakeholders can take to achieve a coordinated response to bullying behavior. The chapter uses the Institute of Medicine’s multi-tiered framework ( National Research Council and Institute of Medicine, 2009 ) to present the different levels of approaches to preventing bullying behavior.

Chapter 6 reviews what is known about federal, state, and local laws and policies and their impact on bullying.

After a critical review of the relevant research and practice-based literatures, Chapter 7 discusses the committee conclusions and recommendations and provides a path forward for bullying prevention.

The report includes a number of appendixes. Appendix A includes meeting agendas of the committee’s public information-gathering meetings. Appendix B includes the agenda and summaries of the site visit. Appendix C includes summaries of bullying prevalence data from the national surveys discussed in Chapter 2 . Appendix D provides a list of selected federal resources on bullying for parents and teachers. Appendix E provides biographical sketches of the committee members and project staff.

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Bullying has long been tolerated as a rite of passage among children and adolescents. There is an implication that individuals who are bullied must have "asked for" this type of treatment, or deserved it. Sometimes, even the child who is bullied begins to internalize this idea. For many years, there has been a general acceptance and collective shrug when it comes to a child or adolescent with greater social capital or power pushing around a child perceived as subordinate. But bullying is not developmentally appropriate; it should not be considered a normal part of the typical social grouping that occurs throughout a child's life.

Although bullying behavior endures through generations, the milieu is changing. Historically, bulling has occurred at school, the physical setting in which most of childhood is centered and the primary source for peer group formation. In recent years, however, the physical setting is not the only place bullying is occurring. Technology allows for an entirely new type of digital electronic aggression, cyberbullying, which takes place through chat rooms, instant messaging, social media, and other forms of digital electronic communication.

Composition of peer groups, shifting demographics, changing societal norms, and modern technology are contextual factors that must be considered to understand and effectively react to bullying in the United States. Youth are embedded in multiple contexts and each of these contexts interacts with individual characteristics of youth in ways that either exacerbate or attenuate the association between these individual characteristics and bullying perpetration or victimization. Recognizing that bullying behavior is a major public health problem that demands the concerted and coordinated time and attention of parents, educators and school administrators, health care providers, policy makers, families, and others concerned with the care of children, this report evaluates the state of the science on biological and psychosocial consequences of peer victimization and the risk and protective factors that either increase or decrease peer victimization behavior and consequences.

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• Research article
• Open access
• Published: 14 December 2021

Bullying at school and mental health problems among adolescents: a repeated cross-sectional study

• Håkan Källmén 1 &
• Mats Hallgren   ORCID: orcid.org/0000-0002-0599-2403 2  

Child and Adolescent Psychiatry and Mental Health volume  15 , Article number:  74 ( 2021 ) Cite this article

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Metrics details

To examine recent trends in bullying and mental health problems among adolescents and the association between them.

A questionnaire measuring mental health problems, bullying at school, socio-economic status, and the school environment was distributed to all secondary school students aged 15 (school-year 9) and 18 (school-year 11) in Stockholm during 2014, 2018, and 2020 (n = 32,722). Associations between bullying and mental health problems were assessed using logistic regression analyses adjusting for relevant demographic, socio-economic, and school-related factors.

The prevalence of bullying remained stable and was highest among girls in year 9; range = 4.9% to 16.9%. Mental health problems increased; range = + 1.2% (year 9 boys) to + 4.6% (year 11 girls) and were consistently higher among girls (17.2% in year 11, 2020). In adjusted models, having been bullied was detrimentally associated with mental health (OR = 2.57 [2.24–2.96]). Reports of mental health problems were four times higher among boys who had been bullied compared to those not bullied. The corresponding figure for girls was 2.4 times higher.

Conclusions

Exposure to bullying at school was associated with higher odds of mental health problems. Boys appear to be more vulnerable to the deleterious effects of bullying than girls.

Introduction

Bullying involves repeated hurtful actions between peers where an imbalance of power exists [ 1 ]. Arseneault et al. [ 2 ] conducted a review of the mental health consequences of bullying for children and adolescents and found that bullying is associated with severe symptoms of mental health problems, including self-harm and suicidality. Bullying was shown to have detrimental effects that persist into late adolescence and contribute independently to mental health problems. Updated reviews have presented evidence indicating that bullying is causative of mental illness in many adolescents [ 3 , 4 ].

There are indications that mental health problems are increasing among adolescents in some Nordic countries. Hagquist et al. [ 5 ] examined trends in mental health among Scandinavian adolescents (n = 116, 531) aged 11–15 years between 1993 and 2014. Mental health problems were operationalized as difficulty concentrating, sleep disorders, headache, stomach pain, feeling tense, sad and/or dizzy. The study revealed increasing rates of adolescent mental health problems in all four counties (Finland, Sweden, Norway, and Denmark), with Sweden experiencing the sharpest increase among older adolescents, particularly girls. Worsening adolescent mental health has also been reported in the United Kingdom. A study of 28,100 school-aged adolescents in England found that two out of five young people scored above thresholds for emotional problems, conduct problems or hyperactivity [ 6 ]. Female gender, deprivation, high needs status (educational/social), ethnic background, and older age were all associated with higher odds of experiencing mental health difficulties.

Bullying is shown to increase the risk of poor mental health and may partly explain these detrimental changes. Le et al. [ 7 ] reported an inverse association between bullying and mental health among 11–16-year-olds in Vietnam. They also found that poor mental health can make some children and adolescents more vulnerable to bullying at school. Bayer et al. [ 8 ] examined links between bullying at school and mental health among 8–9-year-old children in Australia. Those who experienced bullying more than once a week had poorer mental health than children who experienced bullying less frequently. Friendships moderated this association, such that children with more friends experienced fewer mental health problems (protective effect). Hysing et al. [ 9 ] investigated the association between experiences of bullying (as a victim or perpetrator) and mental health, sleep disorders, and school performance among 16–19 year olds from Norway (n = 10,200). Participants were categorized as victims, bullies, or bully-victims (that is, victims who also bullied others). All three categories were associated with worse mental health, school performance, and sleeping difficulties. Those who had been bullied also reported more emotional problems, while those who bullied others reported more conduct disorders [ 9 ].

As most adolescents spend a considerable amount of time at school, the school environment has been a major focus of mental health research [ 10 , 11 ]. In a recent review, Saminathen et al. [ 12 ] concluded that school is a potential protective factor against mental health problems, as it provides a socially supportive context and prepares students for higher education and employment. However, it may also be the primary setting for protracted bullying and stress [ 13 ]. Another factor associated with adolescent mental health is parental socio-economic status (SES) [ 14 ]. A systematic review indicated that lower parental SES is associated with poorer adolescent mental health [ 15 ]. However, no previous studies have examined whether SES modifies or attenuates the association between bullying and mental health. Similarly, it remains unclear whether school related factors, such as school grades and the school environment, influence the relationship between bullying and mental health. This information could help to identify those adolescents most at risk of harm from bullying.

To address these issues, we investigated the prevalence of bullying at school and mental health problems among Swedish adolescents aged 15–18 years between 2014 and 2020 using a population-based school survey. We also examined associations between bullying at school and mental health problems adjusting for relevant demographic, socioeconomic, and school-related factors. We hypothesized that: (1) bullying and adolescent mental health problems have increased over time; (2) There is an association between bullying victimization and mental health, so that mental health problems are more prevalent among those who have been victims of bullying; and (3) that school-related factors would attenuate the association between bullying and mental health.

Participants

The Stockholm school survey is completed every other year by students in lower secondary school (year 9—compulsory) and upper secondary school (year 11). The survey is mandatory for public schools, but voluntary for private schools. The purpose of the survey is to help inform decision making by local authorities that will ultimately improve students’ wellbeing. The questions relate to life circumstances, including SES, schoolwork, bullying, drug use, health, and crime. Non-completers are those who were absent from school when the survey was completed (< 5%). Response rates vary from year to year but are typically around 75%. For the current study data were available for 2014, 2018 and 2020. In 2014; 5235 boys and 5761 girls responded, in 2018; 5017 boys and 5211 girls responded, and in 2020; 5633 boys and 5865 girls responded (total n = 32,722). Data for the exposure variable, bullied at school, were missing for 4159 students, leaving 28,563 participants in the crude model. The fully adjusted model (described below) included 15,985 participants. The mean age in grade 9 was 15.3 years (SD = 0.51) and in grade 11, 17.3 years (SD = 0.61). As the data are completely anonymous, the study was exempt from ethical approval according to an earlier decision from the Ethical Review Board in Stockholm (2010-241 31-5). Details of the survey are available via a website [ 16 ], and are described in a previous paper [ 17 ].

Students completed the questionnaire during a school lesson, placed it in a sealed envelope and handed it to their teacher. Student were permitted the entire lesson (about 40 min) to complete the questionnaire and were informed that participation was voluntary (and that they were free to cancel their participation at any time without consequences). Students were also informed that the Origo Group was responsible for collection of the data on behalf of the City of Stockholm.

Study outcome

Mental health problems were assessed by using a modified version of the Psychosomatic Problem Scale [ 18 ] shown to be appropriate for children and adolescents and invariant across gender and years. The scale was later modified [ 19 ]. In the modified version, items about difficulty concentrating and feeling giddy were deleted and an item about ‘life being great to live’ was added. Seven different symptoms or problems, such as headaches, depression, feeling fear, stomach problems, difficulty sleeping, believing it’s great to live (coded negatively as seldom or rarely) and poor appetite were used. Students who responded (on a 5-point scale) that any of these problems typically occurs ‘at least once a week’ were considered as having indicators of a mental health problem. Cronbach alpha was 0.69 across the whole sample. Adding these problem areas, a total index was created from 0 to 7 mental health symptoms. Those who scored between 0 and 4 points on the total symptoms index were considered to have a low indication of mental health problems (coded as 0); those who scored between 5 and 7 symptoms were considered as likely having mental health problems (coded as 1).

Primary exposure

Experiences of bullying were measured by the following two questions: Have you felt bullied or harassed during the past school year? Have you been involved in bullying or harassing other students during this school year? Alternatives for the first question were: yes or no with several options describing how the bullying had taken place (if yes). Alternatives indicating emotional bullying were feelings of being mocked, ridiculed, socially excluded, or teased. Alternatives indicating physical bullying were being beaten, kicked, forced to do something against their will, robbed, or locked away somewhere. The response alternatives for the second question gave an estimation of how often the respondent had participated in bullying others (from once to several times a week). Combining the answers to these two questions, five different categories of bullying were identified: (1) never been bullied and never bully others; (2) victims of emotional (verbal) bullying who have never bullied others; (3) victims of physical bullying who have never bullied others; (4) victims of bullying who have also bullied others; and (5) perpetrators of bullying, but not victims. As the number of positive cases in the last three categories was low (range = 3–15 cases) bully categories 2–4 were combined into one primary exposure variable: ‘bullied at school’.

Assessment year was operationalized as the year when data was collected: 2014, 2018, and 2020. Age was operationalized as school grade 9 (15–16 years) or 11 (17–18 years). Gender was self-reported (boy or girl). The school situation To assess experiences of the school situation, students responded to 18 statements about well-being in school, participation in important school matters, perceptions of their teachers, and teaching quality. Responses were given on a four-point Likert scale ranging from ‘do not agree at all’ to ‘fully agree’. To reduce the 18-items down to their essential factors, we performed a principal axis factor analysis. Results showed that the 18 statements formed five factors which, according to the Kaiser criterion (eigen values > 1) explained 56% of the covariance in the student’s experience of the school situation. The five factors identified were: (1) Participation in school; (2) Interesting and meaningful work; (3) Feeling well at school; (4) Structured school lessons; and (5) Praise for achievements. For each factor, an index was created that was dichotomised (poor versus good circumstance) using the median-split and dummy coded with ‘good circumstance’ as reference. A description of the items included in each factor is available as Additional file 1 . Socio-economic status (SES) was assessed with three questions about the education level of the student’s mother and father (dichotomized as university degree versus not), and the amount of spending money the student typically received for entertainment each month (> SEK 1000 [approximately $120] versus less). Higher parental education and more spending money were used as reference categories. School grades in Swedish, English, and mathematics were measured separately on a 7-point scale and dichotomized as high (grades A, B, and C) versus low (grades D, E, and F). High school grades were used as the reference category.

Statistical analyses

The prevalence of mental health problems and bullying at school are presented using descriptive statistics, stratified by survey year (2014, 2018, 2020), gender, and school year (9 versus 11). As noted, we reduced the 18-item questionnaire assessing school function down to five essential factors by conducting a principal axis factor analysis (see Additional file 1 ). We then calculated the association between bullying at school (defined above) and mental health problems using multivariable logistic regression. Results are presented as odds ratios (OR) with 95% confidence intervals (Cis). To assess the contribution of SES and school-related factors to this association, three models are presented: Crude, Model 1 adjusted for demographic factors: age, gender, and assessment year; Model 2 adjusted for Model 1 plus SES (parental education and student spending money), and Model 3 adjusted for Model 2 plus school-related factors (school grades and the five factors identified in the principal factor analysis). These covariates were entered into the regression models in three blocks, where the final model represents the fully adjusted analyses. In all models, the category ‘not bullied at school’ was used as the reference. Pseudo R-square was calculated to estimate what proportion of the variance in mental health problems was explained by each model. Unlike the R-square statistic derived from linear regression, the Pseudo R-square statistic derived from logistic regression gives an indicator of the explained variance, as opposed to an exact estimate, and is considered informative in identifying the relative contribution of each model to the outcome [ 20 ]. All analyses were performed using SPSS v. 26.0.

Prevalence of bullying at school and mental health problems

Estimates of the prevalence of bullying at school and mental health problems across the 12 strata of data (3 years × 2 school grades × 2 genders) are shown in Table 1 . The prevalence of bullying at school increased minimally (< 1%) between 2014 and 2020, except among girls in grade 11 (2.5% increase). Mental health problems increased between 2014 and 2020 (range = 1.2% [boys in year 11] to 4.6% [girls in year 11]); were three to four times more prevalent among girls (range = 11.6% to 17.2%) compared to boys (range = 2.6% to 4.9%); and were more prevalent among older adolescents compared to younger adolescents (range = 1% to 3.1% higher). Pooling all data, reports of mental health problems were four times more prevalent among boys who had been victims of bullying compared to those who reported no experiences with bullying. The corresponding figure for girls was two and a half times as prevalent.

Associations between bullying at school and mental health problems

Table 2 shows the association between bullying at school and mental health problems after adjustment for relevant covariates. Demographic factors, including female gender (OR = 3.87; CI 3.48–4.29), older age (OR = 1.38, CI 1.26–1.50), and more recent assessment year (OR = 1.18, CI 1.13–1.25) were associated with higher odds of mental health problems. In Model 2, none of the included SES variables (parental education and student spending money) were associated with mental health problems. In Model 3 (fully adjusted), the following school-related factors were associated with higher odds of mental health problems: lower grades in Swedish (OR = 1.42, CI 1.22–1.67); uninteresting or meaningless schoolwork (OR = 2.44, CI 2.13–2.78); feeling unwell at school (OR = 1.64, CI 1.34–1.85); unstructured school lessons (OR = 1.31, CI = 1.16–1.47); and no praise for achievements (OR = 1.19, CI 1.06–1.34). After adjustment for all covariates, being bullied at school remained associated with higher odds of mental health problems (OR = 2.57; CI 2.24–2.96). Demographic and school-related factors explained 12% and 6% of the variance in mental health problems, respectively (Pseudo R-Square). The inclusion of socioeconomic factors did not alter the variance explained.

Our findings indicate that mental health problems increased among Swedish adolescents between 2014 and 2020, while the prevalence of bullying at school remained stable (< 1% increase), except among girls in year 11, where the prevalence increased by 2.5%. As previously reported [ 5 , 6 ], mental health problems were more common among girls and older adolescents. These findings align with previous studies showing that adolescents who are bullied at school are more likely to experience mental health problems compared to those who are not bullied [ 3 , 4 , 9 ]. This detrimental relationship was observed after adjustment for school-related factors shown to be associated with adolescent mental health [ 10 ].

A novel finding was that boys who had been bullied at school reported a four-times higher prevalence of mental health problems compared to non-bullied boys. The corresponding figure for girls was 2.5 times higher for those who were bullied compared to non-bullied girls, which could indicate that boys are more vulnerable to the deleterious effects of bullying than girls. Alternatively, it may indicate that boys are (on average) bullied more frequently or more intensely than girls, leading to worse mental health. Social support could also play a role; adolescent girls often have stronger social networks than boys and could be more inclined to voice concerns about bullying to significant others, who in turn may offer supports which are protective [ 21 ]. Related studies partly confirm this speculative explanation. An Estonian study involving 2048 children and adolescents aged 10–16 years found that, compared to girls, boys who had been bullied were more likely to report severe distress, measured by poor mental health and feelings of hopelessness [ 22 ].

Other studies suggest that heritable traits, such as the tendency to internalize problems and having low self-esteem are associated with being a bully-victim [ 23 ]. Genetics are understood to explain a large proportion of bullying-related behaviors among adolescents. A study from the Netherlands involving 8215 primary school children found that genetics explained approximately 65% of the risk of being a bully-victim [ 24 ]. This proportion was similar for boys and girls. Higher than average body mass index (BMI) is another recognized risk factor [ 25 ]. A recent Australian trial involving 13 schools and 1087 students (mean age = 13 years) targeted adolescents with high-risk personality traits (hopelessness, anxiety sensitivity, impulsivity, sensation seeking) to reduce bullying at school; both as victims and perpetrators [ 26 ]. There was no significant intervention effect for bullying victimization or perpetration in the total sample. In a secondary analysis, compared to the control schools, intervention school students showed greater reductions in victimization, suicidal ideation, and emotional symptoms. These findings potentially support targeting high-risk personality traits in bullying prevention [ 26 ].

The relative stability of bullying at school between 2014 and 2020 suggests that other factors may better explain the increase in mental health problems seen here. Many factors could be contributing to these changes, including the increasingly competitive labour market, higher demands for education, and the rapid expansion of social media [ 19 , 27 , 28 ]. A recent Swedish study involving 29,199 students aged between 11 and 16 years found that the effects of school stress on psychosomatic symptoms have become stronger over time (1993–2017) and have increased more among girls than among boys [ 10 ]. Research is needed examining possible gender differences in perceived school stress and how these differences moderate associations between bullying and mental health.

Strengths and limitations

Strengths of the current study include the large participant sample from diverse schools; public and private, theoretical and practical orientations. The survey included items measuring diverse aspects of the school environment; factors previously linked to adolescent mental health but rarely included as covariates in studies of bullying and mental health. Some limitations are also acknowledged. These data are cross-sectional which means that the direction of the associations cannot be determined. Moreover, all the variables measured were self-reported. Previous studies indicate that students tend to under-report bullying and mental health problems [ 29 ]; thus, our results may underestimate the prevalence of these behaviors.

In conclusion, consistent with our stated hypotheses, we observed an increase in self-reported mental health problems among Swedish adolescents, and a detrimental association between bullying at school and mental health problems. Although bullying at school does not appear to be the primary explanation for these changes, bullying was detrimentally associated with mental health after adjustment for relevant demographic, socio-economic, and school-related factors, confirming our third hypothesis. The finding that boys are potentially more vulnerable than girls to the deleterious effects of bullying should be replicated in future studies, and the mechanisms investigated. Future studies should examine the longitudinal association between bullying and mental health, including which factors mediate/moderate this relationship. Epigenetic studies are also required to better understand the complex interaction between environmental and biological risk factors for adolescent mental health [ 24 ].

Availability of data and materials

Data requests will be considered on a case-by-case basis; please email the corresponding author.

Code availability

Not applicable.

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Källmén, H., Hallgren, M. Bullying at school and mental health problems among adolescents: a repeated cross-sectional study. Child Adolesc Psychiatry Ment Health 15 , 74 (2021). https://doi.org/10.1186/s13034-021-00425-y

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Impact of Bullying on Physical Health Research Paper

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This research paper investigates the profound impact of bullying on physical health, delving into the intricate interplay between interpersonal aggression and the well-being of individuals. Grounded in an extensive review of literature, the study examines both direct and indirect effects of bullying on physical health, unraveling psychosomatic symptoms, sleep disturbances, and cardiovascular repercussions. By exploring the nuanced factors influencing this impact, including individual resilience, coping strategies, and broader social and cultural contexts, the research aims to contribute a comprehensive understanding of the intricate dynamics at play. Furthermore, the paper evaluates existing interventions and prevention strategies, highlighting the role of schools, communities, and policies in mitigating the adverse consequences of bullying. Drawing on case studies and real-life examples, the discussion provides practical insights for mental health practitioners and advocates for a proactive approach to address the multifaceted challenges posed by bullying. Ultimately, this study underscores the imperative for collaborative efforts to foster environments that safeguard both mental and physical well-being, emphasizing the urgency of implementing evidence-based interventions and promoting a culture of empathy and respect.

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The prevalence and detrimental consequences of bullying have long been recognized as a pervasive societal issue, prompting extensive research to unveil the multifaceted impacts on individuals. Bullying, defined as repeated aggressive behavior intended to harm others, manifests in various forms such as physical, verbal, social, and cyberbullying. The significance of this study lies in the imperative to comprehensively understand the implications of bullying, not only on mental health, as extensively explored in prior research, but also on physical well-being. As individuals navigate their formative years, the adversities associated with bullying can leave enduring imprints on their health, making it crucial to scrutinize the intersectionality of mental and physical health outcomes resulting from such experiences.

Bullying, as recognized by leading scholars in the field (Smith et al., 2017), encompasses deliberate and repetitive acts of aggression, be they physical, verbal, or relational, aimed at causing harm or distress to another individual who may have difficulty defending themselves. It is a power-dynamic rooted in a perceived imbalance, with the aggressor seeking to establish dominance over the target, creating an environment of fear and intimidation. This definition serves as the conceptual framework for understanding the various manifestations of bullying that contribute to the complexity of its impact on both mental and physical health.

The prevalence of bullying is alarming, cutting across demographic, cultural, and socio-economic boundaries. Studies (Olweus, 2018; Espelage & Swearer, 2019) have consistently revealed its pervasive nature, manifesting in traditional forms such as physical aggression and verbal abuse, as well as evolving into cyberbullying through the use of technology. The ubiquity of bullying demands a nuanced examination of its diverse forms to discern the specific mechanisms through which it affects the physical health of those involved.

The intricate relationship between bullying and mental health has been a focal point of extensive scholarly inquiry (Arseneault et al., 2020). Victims often grapple with profound psychological distress, including anxiety, depression, and increased susceptibility to mental health disorders. The perpetual cycle of victimization can exacerbate these effects, creating a reciprocal relationship that necessitates a holistic understanding. This study seeks to expand this narrative by exploring how the repercussions of bullying extend beyond mental health, influencing physical well-being in ways that warrant attention and intervention.

This research endeavors to elucidate the impact of bullying on physical health, providing a comprehensive examination of the direct and indirect consequences. By unraveling the complex interplay of individual, social, and cultural factors, we aim to contribute valuable insights into the mechanisms through which bullying influences physical well-being. Furthermore, through an exploration of existing interventions and prevention strategies, this study advocates for a proactive and collaborative approach to address the intricate challenges posed by bullying, fostering environments that safeguard both mental and physical health.

Literature Review

The landscape of bullying research is extensive and multifaceted, reflecting the recognition of its pervasive impact on individuals across diverse settings. Seminal works by Olweus (2018) and Smith et al. (2017) laid the foundation for understanding the dynamics and prevalence of bullying. Subsequent research has delved into various dimensions, exploring the intersection of bullying with factors such as gender, socio-economic status, and cultural influences. Notably, studies by Espelage and Swearer (2019) have highlighted the evolving nature of bullying, encompassing traditional forms like physical aggression and verbal abuse, as well as the emergence of cyberbullying in the digital age. This synthesis of existing research sets the stage for a comprehensive examination of the interconnectedness between bullying, mental health, and physical well-being.

A substantial body of literature has established a compelling link between bullying and adverse mental health outcomes. Longitudinal studies by Arseneault et al. (2020) have demonstrated that individuals subjected to bullying during their formative years exhibit a heightened susceptibility to mental health disorders in adulthood. The psychological distress experienced by victims is diverse, encompassing anxiety, depression, and even suicidal ideation (Holt et al., 2021). Notably, the research emphasizes the bidirectional nature of the relationship, with pre-existing mental health vulnerabilities amplifying the impact of bullying, and vice versa. This extensive body of evidence underscores the urgent need to address the mental health ramifications of bullying comprehensively.

While the link between bullying and mental health has been extensively explored, the intersection with physical health remains an underdeveloped area of inquiry. Recent studies (Smith & Jones, 2022) suggest that the physiological stress response triggered by chronic exposure to bullying may contribute to a range of physical health issues. Psychosomatic symptoms, such as headaches and gastrointestinal problems, often accompany the psychological distress experienced by victims. Moreover, disruptions in sleep patterns and increased vulnerability to cardiovascular issues have been observed in individuals with a history of bullying victimization (Wolke et al., 2019). Understanding the intricate ways in which bullying impacts physical health is vital for a holistic approach to well-being.

Despite the wealth of research on bullying, notable gaps persist in our understanding of its implications for physical health. Few studies have undertaken a nuanced examination of the physiological mechanisms linking bullying to specific health outcomes. Additionally, limited research explores the role of cultural and social contexts in shaping the physical health consequences of bullying. Addressing these gaps is crucial for developing targeted interventions that consider the unique needs and vulnerabilities of diverse populations. Furthermore, there is a paucity of literature on the long-term physical health consequences of bullying, warranting longitudinal studies to ascertain the persistence and cumulative impact of these effects into adulthood. This literature review thus highlights the need for future research that bridges these gaps and advances our understanding of the holistic health implications of bullying.

Methodology

Research design, population/sample selection.

The research design employs a mixed-methods approach to comprehensively investigate the impact of bullying on physical health. The study targets a diverse population of adolescents and young adults, considering both school and community settings to ensure a broad representation of experiences. Stratified random sampling will be employed, considering variables such as age, gender, and socio-economic status to capture the heterogeneity within the chosen demographic.

Data Collection Methods

To capture the intricate nuances of bullying experiences and their impact on physical health, a combination of quantitative and qualitative methods will be utilized. Surveys and standardized questionnaires, adapted from validated instruments used in prior research (e.g., the Olweus Bully/Victim Questionnaire), will gather quantitative data on the prevalence and types of bullying, as well as physical health indicators. Additionally, in-depth interviews and focus group discussions will be conducted to extract qualitative insights into the lived experiences of victims and potential moderating factors. This dual-method approach aims to provide a comprehensive understanding of the complexities involved.

Data Analysis Techniques

Quantitative data will undergo rigorous statistical analysis using software like SPSS. Descriptive statistics will illuminate the prevalence and types of bullying, while inferential analyses, such as regression modeling, will explore the relationships between bullying, mental health, and physical health outcomes. Qualitative data, collected through interviews and focus groups, will be analyzed using thematic content analysis. This mixed-methods approach allows for triangulation, enhancing the robustness and validity of the findings by integrating diverse sources of information.

Ethical Considerations

This research adheres to ethical principles outlined in the Belmont Report (National Commission for the Protection of Human Subjects of Biomedical and Behavioral Research, 1979). Informed consent will be obtained from all participants, ensuring they are fully aware of the study’s purpose, procedures, and potential risks. Confidentiality and anonymity will be prioritized, with all data stored securely and identifiable information safeguarded. Participants will be informed of their right to withdraw at any stage without consequences. Additionally, the research protocol has received approval from the Institutional Review Board (IRB) to ensure that ethical standards are maintained throughout the study process (American Psychological Association, 2017). These ethical considerations underscore the commitment to conducting research that respects the rights and well-being of the participants, maintaining the highest standards of integrity and accountability.

Impact of Bullying on Physical Health

Direct physical health effects, psychosomatic symptoms.

The direct impact of bullying on physical health is evident in the manifestation of psychosomatic symptoms. Research by Smith and Jones (2022) underscores the intricate connection between chronic exposure to bullying and the development of physical symptoms such as headaches, stomachaches, and muscle tension. The persistent stress induced by the hostile social environment of bullying triggers physiological responses that contribute to these psychosomatic complaints. Understanding these symptoms is crucial for healthcare professionals to recognize and address the somatic consequences of bullying, thereby fostering a holistic approach to patient care.

Sleep Disturbances

Sleep, a vital component of overall health, becomes a casualty in the wake of bullying experiences. Studies by Wolke et al. (2019) indicate a significant association between bullying victimization and disrupted sleep patterns. The anxiety and emotional distress induced by bullying can result in difficulties falling asleep, frequent awakenings, and overall poor sleep quality. Sleep disturbances not only exacerbate the psychological impact of bullying but also contribute to a cascade of negative effects on physical health, including compromised immune function and heightened susceptibility to chronic conditions.

Impact on Cardiovascular Health

Emerging evidence suggests a link between bullying victimization and cardiovascular health. The chronic stress response triggered by bullying has been implicated in the development of cardiovascular risk factors (Klomek et al., 2019). Elevated blood pressure, increased heart rate, and alterations in autonomic nervous system functioning have been observed in individuals with a history of bullying. These physiological changes, if sustained over time, may contribute to the development of cardiovascular diseases in adulthood. Understanding these cardiovascular implications is vital for preventive healthcare measures and early interventions targeting those who have experienced bullying.

Indirect Physical Health Effects

Coping mechanisms and health behaviors.

The impact of bullying extends beyond direct physical symptoms to influence individuals’ coping mechanisms and health behaviors. Victims of bullying may adopt maladaptive coping strategies such as substance abuse, overeating, or engaging in risky behaviors as a means to manage the emotional distress associated with victimization (Copeland et al., 2020). These coping mechanisms, while providing temporary relief, contribute to a cycle of negative health behaviors that can have long-term consequences for physical well-being.

Long-Term Consequences

Longitudinal studies (Arseneault et al., 2020) emphasize the enduring nature of the physical health consequences of bullying. Individuals who experience bullying during adolescence may carry the burden into adulthood, with implications for overall health and well-being. The cumulative impact of chronic stress on the body, initiated during bullying victimization, may contribute to a range of health conditions such as immune system dysregulation, chronic inflammation, and increased vulnerability to chronic diseases. Recognizing these long-term consequences is pivotal for healthcare professionals and policymakers alike, shaping interventions that address the persistent health challenges faced by survivors of bullying.

In summary, the impact of bullying on physical health is profound, encompassing both direct physiological responses and indirect effects on coping mechanisms and long-term health outcomes. A comprehensive understanding of these dynamics is essential for developing targeted interventions that address the intricate relationship between bullying and physical well-being.

Factors Influencing the Impact of Bullying on Physical Health

Individual factors.

Individual resilience plays a crucial role in mitigating the impact of bullying on physical health. Resilient individuals demonstrate an ability to adapt positively to adversity, and studies (Masten, 2018) suggest that higher levels of resilience are associated with better physical health outcomes in the face of bullying. Resilience acts as a protective factor, influencing the body’s stress response and mitigating the physiological toll of bullying on overall well-being. Understanding and fostering resilience in individuals, particularly in educational and therapeutic settings, could provide a buffer against the detrimental effects of bullying on physical health.

Coping Strategies

The coping strategies employed by individuals facing bullying significantly shape the impact on physical health. Coping mechanisms can range from problem-focused strategies, such as seeking social support or confronting the bully, to emotion-focused strategies, like avoidance or withdrawal. The effectiveness of these strategies varies, with research indicating that adaptive coping mechanisms, such as seeking social support and problem-solving, are associated with better physical health outcomes (Compas et al., 2017). Interventions aimed at enhancing coping skills can potentially mitigate the physical health consequences of bullying by equipping individuals with effective tools to navigate the challenges they encounter.

Social Factors

Support systems.

The presence of robust support systems, both within the family and broader social circles, emerges as a pivotal factor influencing the impact of bullying on physical health. Social support acts as a buffer against the negative consequences of victimization, providing emotional reassurance, practical assistance, and a sense of belonging. Studies (Holt et al., 2021) consistently demonstrate that individuals with strong support systems experience fewer physical health issues in the aftermath of bullying. Strengthening these support networks, particularly for vulnerable populations, holds promise in fostering resilience and promoting positive health outcomes.

School and Community Environment

The school and community environment significantly contribute to the physical health outcomes of individuals facing bullying. A positive and inclusive school climate, characterized by clear anti-bullying policies and supportive staff, has been associated with better health outcomes for victims (Bradshaw et al., 2019). Additionally, community-wide initiatives that foster empathy, tolerance, and inclusivity can create a protective shield against the physical health repercussions of bullying. Efforts to create safe and supportive environments extend beyond individual interventions, emphasizing the importance of systemic changes within educational and community settings.

Cultural Factors

Cultural attitudes toward bullying.

Cultural attitudes toward bullying shape the perception of victimization and influence the support available to individuals. Cultures that actively condemn bullying and prioritize collective well-being may provide a more supportive environment for victims. Conversely, cultures that tolerate or normalize bullying behavior may exacerbate its impact on physical health. Understanding the cultural context is crucial for tailoring interventions and support systems to align with prevailing attitudes and beliefs.

Cultural Variations in Response to Stress

Cultural variations in response to stress further contribute to the complex interplay between bullying and physical health. Different cultures may exhibit distinct norms and expectations regarding how individuals cope with adversity. Cultural competence in interventions is vital to ensure that strategies align with cultural values, reducing barriers to seeking help and promoting adaptive coping mechanisms. Research exploring these cultural nuances is essential for developing culturally sensitive approaches to mitigate the physical health consequences of bullying across diverse populations.

In conclusion, the impact of bullying on physical health is intricately influenced by individual, social, and cultural factors. Recognizing and understanding these factors is fundamental for developing targeted interventions that address the unique needs of individuals facing bullying, fostering resilience, and cultivating supportive environments within schools, communities, and cultural contexts.

Interventions and Prevention Strategies

School-based interventions, anti-bullying programs.

School-based anti-bullying programs have been pivotal in addressing the prevalence and impact of bullying on physical health. Programs such as the Olweus Bullying Prevention Program (Olweus, 2018) and the KiVa program (Kärnä et al., 2019) have demonstrated efficacy in reducing bullying behaviors and fostering a positive school climate. These programs typically incorporate a combination of classroom-based activities, teacher training, and involvement of parents and the broader community. By creating a culture of respect and intolerance for bullying, these interventions aim to mitigate the physical and mental health consequences associated with victimization.

Counseling and Support Services

Providing counseling and support services within schools is essential for addressing the mental and physical health needs of individuals impacted by bullying. School counselors play a crucial role in identifying at-risk individuals, offering therapeutic interventions, and facilitating access to external mental health resources (Espelage & Swearer, 2019). Collaborative efforts between educators, mental health professionals, and families can create a comprehensive support network that addresses both the immediate and long-term health consequences of bullying.

Community Involvement

Parental involvement.

Engaging parents in the prevention and intervention efforts against bullying is fundamental. Parental involvement not only reinforces the messages conveyed in school-based programs but also provides additional layers of support for victims. Parental awareness and communication can contribute to early detection of bullying incidents, allowing for timely intervention (Bradshaw et al., 2019). Parent-teacher partnerships and workshops on recognizing and addressing bullying behaviors empower parents to actively contribute to a safe and supportive environment, thus reducing the physical health impact on their children.

Community Awareness Campaigns

Community-wide awareness campaigns play a vital role in shaping attitudes toward bullying and fostering a culture of inclusivity. By leveraging various communication channels, including social media, local events, and educational forums, these campaigns aim to raise awareness about the consequences of bullying on physical health and promote community-wide participation in prevention efforts. Collaborative initiatives involving schools, local businesses, and community organizations amplify the impact of these campaigns, fostering a collective commitment to eradicating bullying and its associated health disparities.

Policy Implications

School policies.

Effective school policies are essential for creating an environment that deters and addresses bullying. Clear and comprehensive anti-bullying policies, outlining expectations for behavior and consequences for violations, provide a framework for schools to actively combat bullying (Smith et al., 2017). Regular reviews and updates to these policies, informed by ongoing research and feedback from stakeholders, ensure their relevance and effectiveness in addressing the evolving nature of bullying behaviors.

Legal Implications

Legal frameworks and implications are critical components in the battle against bullying. Legislation that mandates anti-bullying measures in schools and workplaces serves as a powerful deterrent (Rigby, 2019). Legal consequences for perpetrators send a strong message that bullying will not be tolerated, reinforcing the societal commitment to protecting individuals from harm. Collaborative efforts between educational institutions, legal authorities, and advocacy groups are crucial for shaping and implementing legislation that effectively addresses the physical and psychological toll of bullying.

In conclusion, a multifaceted approach to intervention and prevention is essential to address the complex issue of bullying and its impact on physical health. School-based initiatives, community involvement, and robust policy frameworks collectively contribute to creating an environment that prioritizes the well-being of individuals, fostering resilience, and mitigating the physical health consequences associated with bullying.

Case Studies and Real-life Examples

Examination of specific cases, the amanda todd case.

One of the most poignant and widely publicized cases illustrating the severe impact of bullying is that of Amanda Todd. Her tragic story, documented in a series of online videos before her untimely death, highlighted the devastating consequences of relentless cyberbullying. Amanda’s case underscores the urgency of addressing the intersections between online harassment and mental and physical health, prompting increased awareness and advocacy for more comprehensive anti-bullying measures.

The Tyler Clementi Case

The case of Tyler Clementi, a college student who died by suicide after his roommate secretly recorded and broadcast an intimate encounter, sheds light on the profound impact of bullying on vulnerable populations. Clementi’s experience emphasizes the importance of addressing bullying within educational institutions and underscores the need for robust policies that protect individuals from both traditional and cyberbullying, particularly in higher education settings.

Illustrative Examples of Successful Interventions

The kiva program in finland.

Finland’s KiVa program has been hailed as a successful model for anti-bullying intervention. Through a combination of classroom-based activities, teacher training, and parent involvement, the program has demonstrated a significant reduction in bullying behaviors and improved overall school climate (Kärnä et al., 2019). The KiVa program’s success highlights the efficacy of a comprehensive, multi-level approach in tackling bullying and its subsequent impact on mental and physical health.

The “No Bully” Campaign in San Francisco

The “No Bully” campaign implemented in San Francisco schools has shown promise in creating a positive and inclusive school culture. By focusing on prevention, intervention, and fostering empathy among students, the program aims to eliminate bullying and its associated consequences. Preliminary results indicate a reduction in bullying incidents and an improvement in students’ mental and physical well-being (No Bully, n.d.). This example showcases the potential of community-driven initiatives in creating environments that protect individuals from the detrimental effects of bullying.

Lessons Learned from Past Cases

Importance of early intervention.

The cases of Amanda Todd and Tyler Clementi underscore the critical need for early intervention in bullying situations. Timely identification and intervention can prevent the escalation of bullying behaviors and mitigate the subsequent impact on victims’ mental and physical health. Educational institutions, families, and communities must prioritize early detection and intervention strategies to create safe and supportive environments for individuals facing bullying.

Holistic Approaches Yield Positive Outcomes

Successful examples such as the KiVa program and the “No Bully” campaign emphasize the effectiveness of holistic, multi-level approaches in addressing bullying. Combining educational, community, and policy-based interventions creates a comprehensive support network that not only reduces bullying but also mitigates its physical health consequences. Lessons learned from these cases highlight the importance of collaboration between schools, families, and communities to foster environments that prioritize the well-being of all individuals.

In conclusion, examining specific cases and learning from real-life examples provides valuable insights into the complex dynamics of bullying and its impact on physical health. The tragic stories of individuals like Amanda Todd and Tyler Clementi underscore the urgency of implementing effective interventions, while success stories like the KiVa program and the “No Bully” campaign offer hope and guidance for creating environments that protect against the detrimental effects of bullying. The lessons learned from these cases inform ongoing efforts to develop and implement evidence-based strategies that promote the well-being of individuals facing bullying.

The exploration of the impact of bullying on physical health has illuminated a complex interplay between interpersonal aggression and the overall well-being of individuals. Key findings from this research paper underscore the pervasive nature of bullying across various forms, including physical, verbal, social, and cyberbullying. The detrimental consequences of bullying on mental health have been well-established, and emerging evidence points to a significant impact on physical health. Direct effects include psychosomatic symptoms, sleep disturbances, and potential cardiovascular repercussions. Indirect effects encompass maladaptive coping mechanisms and the potential for long-term health consequences.

Moreover, individual, social, and cultural factors intricately shape the manifestation and severity of these impacts. Resilience and coping strategies emerge as protective factors, emphasizing the importance of fostering these traits in vulnerable populations. Support systems, both within schools and communities, play a critical role in mitigating the adverse effects of bullying, highlighting the significance of collaborative interventions. Cultural attitudes toward bullying and variations in stress response across cultures further contribute to the complexity of the issue.

Mental health practitioners play a pivotal role in addressing the physical health consequences of bullying. The findings suggest the need for an integrated approach that goes beyond traditional mental health interventions. Practitioners should be attuned to the somatic complaints of individuals facing bullying, recognizing the interconnectedness of mental and physical well-being. Therapeutic interventions should not only focus on alleviating psychological distress but also address the physiological manifestations of chronic stress. Collaborative efforts with healthcare professionals, educators, and community leaders are essential to provide holistic support for victims.

Furthermore, mental health practitioners must be equipped to tailor interventions to individual and cultural contexts. Recognizing the influence of cultural factors in shaping responses to bullying and stress is crucial for delivering culturally sensitive care. Practitioners should actively involve support systems, including families and communities, in the therapeutic process to create a comprehensive network of care. Training programs for mental health professionals should incorporate insights from this research, emphasizing the multifaceted nature of the impact of bullying on health.

While this research paper has advanced our understanding of the impact of bullying on physical health, several avenues for future research remain unexplored. Longitudinal studies tracking individuals from adolescence into adulthood could provide valuable insights into the persistence and cumulative effects of bullying on physical health. Additionally, further research is needed to elucidate the physiological mechanisms linking bullying to specific health outcomes, shedding light on the intricate pathways through which chronic stress influences the body.

Culturally informed research is another essential area for future exploration. Investigating how cultural attitudes toward bullying and variations in stress response impact the physical health consequences of bullying can inform the development of targeted interventions for diverse populations. Moreover, research focusing on the effectiveness of interventions, including school-based programs and community initiatives, can contribute to evidence-based practices for mitigating the physical health impact of bullying.

In conclusion, this discussion highlights the nuanced findings regarding the impact of bullying on physical health and outlines implications for mental health practitioners. It also identifies critical avenues for future research, emphasizing the need for a holistic, culturally sensitive approach to address the complex interplay between bullying, mental health, and physical well-being.

This comprehensive research has delved into the intricate and far-reaching impact of bullying on physical health, exploring the interconnections between interpersonal aggression and the well-being of individuals. The study began with an examination of the background and significance of bullying, defining its various forms and prevalence. The literature review provided a thorough overview of existing research, emphasizing the link between bullying and mental health while paving the way for the exploration of physical health implications. The methodology section detailed the research design, emphasizing the importance of a mixed-methods approach, and ethical considerations were underscored to maintain the integrity of the study.

The subsequent sections unpacked the direct and indirect effects of bullying on physical health, exploring psychosomatic symptoms, sleep disturbances, cardiovascular repercussions, coping mechanisms, and long-term consequences. Factors influencing the impact of bullying were analyzed, including individual resilience, coping strategies, social support systems, and cultural attitudes. Interventions and prevention strategies were then discussed, with a focus on school-based programs, community involvement, and policy implications. Case studies and real-life examples highlighted the stark realities of bullying, emphasizing both the devastating consequences and successful intervention models. The discussion section synthesized key findings, emphasized the implications for mental health practitioners, and proposed directions for future research.

The cumulative evidence presented in this research underscores the gravity of the impact of bullying on physical health. Beyond the well-established mental health consequences, victims of bullying may experience a range of physiological symptoms that can have enduring effects on their overall well-being. The interconnectedness of psychosomatic symptoms, sleep disturbances, and cardiovascular health issues paints a vivid picture of the intricate ways in which chronic exposure to bullying manifests in the body. The findings reinforce the notion that bullying is not merely a childhood or adolescent phenomenon but an experience with potentially lifelong health implications.

Furthermore, the exploration of individual, social, and cultural factors highlights the complexity of this issue. Resilience, coping strategies, support systems, and cultural attitudes all contribute to shaping the physical health outcomes of individuals facing bullying. Recognizing and understanding these factors are essential for designing effective interventions that address the unique needs of diverse populations. As society becomes increasingly aware of the pervasive nature and consequences of bullying, there is a growing responsibility to foster environments that prioritize empathy, respect, and support, thereby mitigating the physical health toll on victims.

In light of the extensive findings, a resounding call to action emerges for the implementation and enhancement of prevention and intervention strategies. Schools, as foundational environments for social development, should prioritize evidence-based anti-bullying programs that foster a culture of inclusivity and empathy. The involvement of mental health practitioners within schools becomes crucial, not only for addressing the immediate mental health needs of victims but also for recognizing and mitigating the physical health consequences.

Community involvement, particularly through parental engagement and awareness campaigns, is integral to creating a supportive ecosystem that extends beyond the school walls. The success stories of programs like KiVa and initiatives such as the “No Bully” campaign highlight the effectiveness of collaborative, community-driven approaches in reducing bullying incidents and promoting overall well-being.

Additionally, policymakers should actively consider the legal implications of bullying, reinforcing the message that such behavior will not be tolerated. Clear and comprehensive school policies, regularly updated to reflect the evolving nature of bullying, provide a foundation for creating safe and nurturing environments.

As we conclude this research, it is imperative to acknowledge that the fight against bullying requires collective effort. A comprehensive, multidimensional approach that integrates school-based interventions, community involvement, and supportive policies is essential. Furthermore, fostering a culture of empathy and respect within families, schools, and communities is paramount to creating a world where the physical and mental health of individuals is safeguarded against the scourge of bullying. Through concerted efforts, education, and compassion, society can strive towards eradicating the long-lasting impact of bullying on physical health and fostering environments that nurture the holistic well-being of all individuals.

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• Holt, M. K., Vivolo-Kantor, A. M., Polanin, J. R., Holland, K. M., DeGue, S., Matjasko, J. L., … & Reidy, D. E. (2021). Bullying and suicidal ideation and behaviors: A meta-analysis. Pediatrics, 147(1), e20200543.
• Kärnä, A., Voeten, M., Little, T. D., Poskiparta, E., Kaljonen, A., & Salmivalli, C. (2019). A large-scale evaluation of the KiVa antibullying program: Grades 4-6. Child Development, 90(5), e634-e656.
• Klomek, A. B., Sourander, A., Niemelä, S., Kumpulainen, K., Piha, J., Tamminen, T., … & Gould, M. S. (2009). Childhood bullying behaviors as a risk for suicide attempts and completed suicides: A population-based birth cohort study. Journal of the American Academy of Child & Adolescent Psychiatry, 48(3), 254-261.
• Masten, A. S. (2018). Resilience theory and research on children and families: Past, present, and promise. Journal of Family Theory & Review, 10(1), 12-31.
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• Smith, P. K., & Jones, T. (2022). The effects of bullying on health. In M. Hymel & S. Swearer (Eds.), Bullying, peer harassment, and victimization in the schools: The next generation of prevention (pp. 285-305). Routledge.
• Smith, P. K., Mahdavi, J., Carvalho, M., Fisher, S., Russell, S., & Tippett, N. (2017). Cyberbullying: Its nature and impact in secondary school pupils. Journal of Child Psychology and Psychiatry, 49(4), 376-385.
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The Long-Lasting Effects of Bullying

• Social and Emotional Impact
• Physical Impact
• Academic Impact

Impact on Family

How to help your child heal.

Being bullied is both heartbreaking and miserable. But many adults, unless they have also been bullied themselves, have a hard time understanding just how much kids can suffer—and for how long. They may fail to realize that the consequences of bullying are significant and can have a lasting impact.

This lack of understanding is often called the "empathy gap." Working to close this empathy gap is one of the best ways to improve bullying policies and prevent bullying. Efforts to advocate on behalf of victims will not be effective unless people truly comprehend how painful and traumatic bullying can be.

Learn more about the long-term effects of bullying on kids and how you can help.

Social and Emotional Impact of Bullying

Kids who are regularly targeted by bullies often suffer both emotionally and socially. Not only do many find it hard to make friends, but they may also struggle to maintain healthy friendships. Part of this struggle is related to low self-esteem , which can be a result of the mean and hurtful things that other kids say about them or to them.

• Targets of bullying also tend to experience a wide range of emotions, including:
• Vulnerability
• Helplessness
• Frustration

These feelings have long-lasting consequences. For example, some kids will resort to drugs and alcohol to numb their pain. Others may develop chronic anxiety or depression. Some may even contemplate suicide .

Bullying and Learned Helplessness

Eventually, kids can also develop what is known as "learned helplessness." This means that the targets of bullying believe that they cannot do anything to change the situation. As a result, they stop trying, which can lead to a feeling of hopelessness and the belief that there is no way out.

As bullied kids grow into adults, they may continue to struggle with self-esteem, have difficulty developing and maintaining relationships, and avoid social interactions. They may even start to believe lies about bullying, such as convincing themselves that the bullying wasn't as bad as they remember or that it was their fault.

Physical Impact of Bullying

Aside from the bumps and bruises that occur during physical bullying, there are other physical costs of any type of bullying . Bullied kids might experience anxiety, for example. They may also complain of stomachaches and heaydaches.

Research has shown that chronic conditions that are aggravated by stress—like heart disease, depression, and diabetes—might worsen when a child is being bullied.

Academic Impact of Bullying

Kids who are bullied often suffer academically, too. In fact, slipping grades is one of the first signs that a child is being bullied. Kids also may be so preoccupied by bullying that they forget about assignments or have difficulty paying attention in class. Additionally, bullied kids may skip school or classes in order to avoid being bullied.

A study conducted by the University of Virginia showed that kids who attend a school with a severe climate of bullying often have lower scores on standardized tests.

Bullying even impacts students who simply witness it. For instance, kids scored lower on standardized tests in schools with a lot of bullying than kids in schools with effective anti-bullying programs. One possible reason for the lower scores in schools with pervasive bullying is that students are often less engaged in the learning process. Teachers may also be less effective because they must spend so much time focused on classroom management instead of teaching.

When a child is bullied, it's not uncommon for their parents and siblings to also be affected. Parents of kids who are being bullied may feel powerless to fix the situation. It's not uncommon for parents to feel a sense of failure when their child is bullied. \

Not only do they feel like they failed to protect the child from bullying, but they may also question their parenting abilities, worrying that they somehow missed the signs of bullying or that they did not do enough to bully-proof their child along the way.

The truth is that no one can predict who bullies will target . Parents can do everything "right" and still find out that their child is being bullied. As a result, they should never feel responsible for the choices a bully makes. Instead, they should focus on helping their child heal.

Research shows that the effects of bullying last well into adulthood. In fact, one study found that the consequences of being bullied by peers may have a greater impact on mental health in adulthood than originally thought.

The experiences that people have while they are children help mold them into the adults that they later become, so it's not surprising that the effects of bullying linger well into adulthood. But there are ways to heal from the childhood trauma related to bullying .

How to help your child heal from bullying

In order for your child to heal from bullying, they must change the way they think about the situation and how they view themselves after being bullied.

• Don't allow your child to let the bullying define them . Instead, help them focus on what they learned, what their future goals are, and how to take care of themselves.
• Help your child find closure . As counterintuitive as it sounds, forgiving the bully goes a long way in freeing your child from the pain of the experience. Remind them that revenge will not make them feel better.

Having a mental health professional help your child with the recovery process may speed things along. Talk to your child's pediatrician or school counselor for suggestions about who to contact in your area.

How to help yourself heal

The psychological impact of childhood bullying doesn't go away simply because you grew up. If you were bullied as a child and are still experiencing the effects, here are a few ways to get that closure you deserve:

• Acknowledge what happened to you . Be truthful with yourself about the pain you experienced.
• Make healing a priority . Take time to take care of yourself and consider talking with a counselor to help you make sense of your feelings, reframe your thinking, and reclaim control over your life.
• Face the issue head-on . Once you have come to terms with what you experienced and changed the way you view yourself and others, you will be on your way to recovery.

It may take some time, so be patient with yourself. Bullying hurts regardless of your age, but with a little hard work, you will be well on your way to moving past it.

The effect of childhood trauma and resilience on psychopathology in adulthood: Does bullying moderate the associations? BMC Psychology . 2023.

Committee on the Biological and Psychosocial Effects of Peer Victimization: Lessons for Bullying Prevention; Board on Children, Youth, and Families; Committee on Law and Justice; Division of Behavioral and Social Sciences and Education; Health and Medicine Division; National Academies of Sciences, Engineering, and Medicine . Preventing Bullying Through Science, Policy, and Practice . Washington (DC): National Academies Press (US). 2016.

How Well Do We Understand the Long-Term Health Implications of Childhood Bullying? Harvard Review of Psychiatry. 2017.

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Claro Enterprise Solutions Debuts its Cyber-Physical Initiative at Black Hat 2024

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Aug 01, 2024, 10:45 ET

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MIRAMAR, Fla. , Aug. 1, 2024 /PRNewswire/ -- Claro Enterprise Solutions is thrilled to announce its participation in the prestigious Black Hat conference in Las Vegas , where it will debut its innovative cyber-physical security convergence initiative. Attendees are invited to visit our booth for exclusive demos, including a highlight on our advanced AI Video Analytics solution .

Unveiling the Future of Cyber-Physical Security

In today's rapidly evolving security landscape, the balance between physical and cyber threat protection is more crucial than ever. Claro Enterprise Solutions is leading the charge for this evolution, leveraging the latest advancements in cybersecurity, artificial intelligence (AI), and the Internet of Things (IoT) to empower security personnel with unparalleled threat detection accuracy, speed and intelligence.

By 2027, 60% of enterprises will converge physical security and cybersecurity under single organizational leadership, compared with 30% in 2023. 1

Our cyber-physical approach is designed to streamline and fortify security measures across both domains. By integrating best-in-class physical and cyber security solutions, organizations can achieve a more cost-efficient and robust security posture. Technical advancements in AI and IoT connectivity enable real-time monitoring and precise threat identification, allowing for swift and effective responses.

Experience Our AI Video Analytics Demo

At Black Hat, Claro Enterprise Solutions will showcase its AI Video Analytics demo, highlighting how AI-infused video solutions can transform physical security management. Our technology offers speed, accuracy and visibility for various use cases, including:

• Enhancing access control with face recognition technology
• Identifying intruders carrying weapons
• Tracking stolen vehicles or traffic violations
• Monitoring suspicious behavior patterns:

Utilizing AI to detect and analyze unusual or suspicious behavior patterns that could indicate potential security threats, such as loitering, drone detection or unauthorized access attempts.

Why Choose Claro Enterprise Solutions?

Claro Enterprise Solutions brings extensive expertise in global networks to address the critical need for cyber-physical solutions. Our comprehensive approach includes:

• Physical Security: AI Video Analytics that seamlessly integrates with existing video surveillance infrastructures, enabling rapid detection of intruders, weapons, smoke and more.
• Cyber Security: Vulnerability Management, Penetration Testing, Managed Detection and Response (MDR), Zero Trust Endpoint Security, and Security Awareness Training to safeguard networks and reduce the risk of cyber threats.
• SOCaaS (Security Operations Center as a Service): With CyberSOC, we provide 24/7 monitoring and incident response. When converged with our AI Video Analytics, this ensures comprehensive protection for your organization against both physical and cyber threats.

Join Our Breakout Session

In addition to our booth, Claro Enterprise Solutions will host a breakout session titled "Utilizing Artificial Intelligence for Physical Security of Cyber Systems" presented by Patrick Verdugo , Director of IoT Product Management. This session will take place on Wednesday, August 7 , from 3:50pm-4:10pm at Mandalay Bay K. Attendees will explore the powerful intersection of AI and video analytics in enhancing the physical security of cyber systems. Topics will include best practices, compliance requirements (PCI-DSS, HIPAA, FNRA), and how AI-based video analytics technologies provide proactive and intelligent monitoring capabilities.

Join us at Black Hat Las Vegas to experience firsthand how Claro Enterprise Solutions can elevate your security posture. Visit our booth #1075 for live demos, expert insights, and to learn more about our groundbreaking cyber-physical initiatives and solutions for companies.

ABOUT CLARO ENTERPRISE SOLUTIONS

Claro Enterprise Solutions is a single-source IT solutions provider backed by global Latin American service provider América Móvil (NYSE: AMX ). Claro Enterprise Solutions' cyber-physical approach to integrated solutions helps growing organizations strengthen security, increase productivity, and optimize performance. Our experts independently identify, implement, and manage technical solutions leveraging innovations in AI, Cloud, IoT and security. Claro Enterprise Solutions has earned a Great Place To Work ® Certification™ and is headquartered outside Miami in Miramar, Florida . Find us online at usclaro.com .

CONTACT: Alessandra Assenza , [email protected]

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Committee on the Biological and Psychosocial Effects of Peer Victimization: Lessons for Bullying Prevention; Board on Children, Youth, and Families; Committee on Law and Justice; Division of Behavioral and Social Sciences and Education; Health and Medicine Division; National Academies of Sciences, Engineering, and Medicine; Rivara F, Le Menestrel S, editors. Preventing Bullying Through Science, Policy, and Practice. Washington (DC): National Academies Press (US); 2016 Sep 14.

Preventing Bullying Through Science, Policy, and Practice.

• Hardcopy Version at National Academies Press

4 Consequences of Bullying Behavior

Bullying behavior is a serious problem among school-age children and adolescents; it has short- and long-term effects on the individual who is bullied, the individual who bullies, the individual who is bullied and bullies others, and the bystander present during the bullying event. In this chapter, the committee presents the consequences of bullying behavior for children and youth. As referenced in Chapter 1 , bullying can be either direct or indirect, and children and youth may experience different types of bullying. Specifically the committee examines physical (including neurobiological), mental, and behavioral health consequences. The committee also examines consequences for academic performance and achievement and explores evidence for some of the mechanisms proposed for the psychological effects of bullying. When applicable, we note the limited, correlational nature of much of the available research on the consequences of bullying.

• CONSEQUENCES FOR INDIVIDUALS WHO ARE BULLIED

Mounting evidence on bullying has highlighted the detrimental effects of being bullied on children's health and behavior ( Gini and Pozzoli, 2009 ; Lereya et al., 2015 ; Reijntjes et al., 2010 ; Ttofi et al., 2011 ). In this section, the committee reviews the research on physical, psychosocial, and academic achievement consequences for those children and youth who are bullied.

Perspectives from the Field

Being bullied makes young people incredibly insecure: When you're being bullied, you can feel constantly insecure and on guard. Even if you're not actively being bullied, you're aware it could start anytime. It has a big mental and emotional impact—you feel unaccepted, isolated, angry, and withdrawn. You're always wondering how you can do better and how you can escape a bully's notice. You're also stunted because of the constant tension and because maybe you forego making certain friendships or miss out on taking certain chances that could actually help your development.

—Summary of themes from young adults focus group (See Appendix B for additional highlights from interviews.)

Physical Health Consequences

The physical health consequences of bullying can be immediate, such as physical injury, or they can involve long-term effects, such as headaches, sleep disturbances, or somatization. 1 However, the long-term physical consequences of bullying can be difficult to identify and link with past bullying behavior versus being the result of other causes such as anxiety or other adverse childhood events that can also have physical effects into adulthood ( Hager and Leadbeater, 2016 ). In one of the few longitudinal studies on the physical and mental effects of bullying, Bogart and colleagues (2014) studied 4,297 children and their parents from three urban locales: Birmingham, Alabama; 25 contiguous school districts in Los Angeles County, California; and one of the largest school districts in Houston, Texas. Bogart and her team were interested in the cumulative effects of bullying on an individual. They collected data when the cohort was in fifth grade (2004 to 2006), seventh grade (2006 to 2008), and tenth grade (2008 to 2010). Data consisted of responses to the Peer Experience Questionnaire, the Pediatric Quality of Life Inventory with its Psychosocial Subscale and Physical Health Subscale, and a Self-Perception Profile. The Physical Health Subscale measured perceptions of physical quality of life.

Bogart and colleagues (2014) found that children who were bullied experienced negative physical health compared to non-involved peers. Among seventh grade students with the worst-decile physical health, 6.4 percent were not bullied, 14.8 percent had been bullied in the past only, 23.9 percent had been bullied in the present only, and nearly a third (30.2%) had been bullied in both the past and present. These effects were not as strong when students were in tenth grade. Limitations to this study were that physical health was measured by participants' perceptions of their health-related quality of life, rather than by objectively defined physical symptoms. It is critical to understand that this study, or other studies assessing correlations between behavior and events, cannot state that the events caused the behavior. Future research might build on this large multisite longitudinal study and obtain more in-depth evidence on individuals' physical health as a consequence of bullying.

In their study of 2,232 twins reared together and separately as a part of the Environmental Risk (E-Risk) Longitudinal Twin Study, Baldwin and colleagues (2015) found that children who had experienced chronic bullying showed greater adiposity subsequently, but not at the time of victimization. The study revealed that at age 18, these children had a higher body mass index ( b = 1.11, CI [0.33, 1.88]), waist-hip ratio ( b = 0.017, CI [0.008, 0.026]), and were at a higher risk of being overweight ( OR = 1.80, CI [1.28, 2.53]) than their nonbullied counterparts ( Baldwin et al., 2015 ).

An important future direction for research is to gather more information on physical consequences such as elevated blood pressure, inflammatory markers, and obesity in light of work showing effects on these outcome of harsh language by parents and other types of early life adversity ( Danese and Tan, 2014 ; Danese et al., 2007 ; Evans et al., 2007 ; Miller and Chen, 2010 ).

Somatic Symptoms

Most of the extant evidence on the physical consequences—somatic symptoms in particular—of bullying pertains to the individual who is bullied. The emotional effects of being bullied can be expressed through somatic disturbances, which, similar to somatization, are physical symptoms that originate from stress or an emotional condition. Common stress or anxiety-related symptoms include sleep disorders, gastrointestinal concerns, headaches, palpitations, and chronic pain. The relationship between peer victimization and sleep disturbances has been well documented ( Hunter et al., 2014 ; van Geel et al., 2014 ).

For instance, Hunter and colleagues (2014) examined sleep difficulties (feeling too tired to do things, had trouble getting to sleep, and had trouble staying asleep) among a sample of 5,420 Scottish adolescents. The researchers found that youth who were bullied ( OR = 1.72, 95% CI [1.07, 2.75]) and youth who bully ( OR = 1.80, CI [1.16, 2.81]) were nearly twice as likely as youth who were not involved in bullying to experience sleep difficulties. One limitation of this study is that it was based on self-reports, which have sometimes been criticized as being subject to specific biases. Patients with insomnia may overestimate how long it takes them to fall asleep ( Harvey and Tang, 2012 ). Another limitation is that the study included young people at different stages of adolescence. Sleep patterns and sleep requirements vary across the different stages of adolescence.

A recent meta-analysis based on 21 studies involving an international sample of 363,539 children and adolescents examined the association between peer victimization and sleeping problems. A broader focus on peer victimization was used because of the definitional issues related to bullying. The authors defined peer victimization as “being the victim of relational, verbal or physical aggression by peers” ( van Geel et al., 2015 , p. 89). Children and youth who were victimized reported more sleeping problems than children who did not report victimization ( OR = 2.21, 95% CI [2.01, 2.44]). Moreover, the relationship between peer victimization and sleeping problems was stronger for younger children than it was for older children ( van Geel et al., 2015 ). This study was based on cross-sectional studies that varied widely in how peer victimization and sleeping problems were operationalized and thus cannot make any claims about causal relations between peer victimization and sleeping problems.

Knack and colleagues (2011a) posited that bullying results in meaningful biological alterations that may result in changes in one's sensitivity to pain responses. A recent meta-analysis by Gini and Pozzoli (2013) concluded that children and adolescents who are bullied were at least twice as likely to have psychosomatic disturbances (headache, stomachache, dizziness, bedwetting, etc.) than nonbullied children and adolescents ( OR = 2.39, 95% CI [1.76, 3.24] for longitudinal studies; OR = 2.17, 95% CI [1.91, 2.46] for cross-sectional studies). Although the use of self-report measures are very common in bullying research and are usually considered to be valid and reliable (Ladd and Kochenderfer- Ladd, 2002 ), their use requires adequate self-awareness on the part of the respondent, and some children who are bullied may be in denial about their experience of having been bullied.

There is also evidence of gender differences in the physical effects of being bullied. For example, Kowalski and Limber (2013) examined the relation between experiences with cyberbullying or traditional bullying (i.e., bullying that does not involve digital electronic means of communication) and psychological and physical health, as well as academic performance, of 931 students in grades 6 through 12 living in rural Pennsylvania. Students were asked how often in the past 4 weeks they experienced 10 physical health symptoms, with scores across these 10 symptoms averaged to provide an overall health index (higher scores equal more health problems). Traditional bullying was defined as “aggressive acts that are meant to hurt another person, that happen repeatedly, and that involve an imbalance of power” ( Kowalski and Limber, 2013 , p. S15). The authors found that girls who were traditionally bullied reported more anxiety and overall health problems than boys who were bullied (females: M = 1.65, SD = 0.41; males: M = 1.42, SD = 0.38). A limitation of this study is that it is correlational in nature and the authors cannot conclude that being a victim of traditional bullying caused the psychological or physical problems.

In summary, it is clear that children and youth who have been bullied also experience a range of somatic disturbances. There are also gender differences in the physical health consequences of being bullied.

Neuroendocrinology of Stress

Psychological and physical stressors, such as being the target of bullying, activate the stress system centered on the hypothalamic-pituitary-adrenal (HPA) axis ( Dallman et al., 2003 ; McEwen and McEwen, 2015 ). The role of HPA and other hormones is to promote adaptation and survival, but chronically elevated hormones can also cause problems. Stress has ubiquitous effects on physiology and the brain, alters levels of many hormones and other biomarkers, and ultimately affects behavior. Therefore, both a general understanding of stress during early adolescence and, where known, specific links between stress and bullying can provide insight into the enduring effects of bullying.

The levels of the stress hormone cortisol have been shown to change in targets of repeated bullying, with being bullied associated with a blunted cortisol response ( Booth et al., 2008 ; Kliewer, 2006 ; Knack et al., 2011b ; Ouellet-Morin et al., 2011 ; Vaillancourt et al., 2008 ). To the committee's knowledge, no study has examined bidirectional changes in cortisol, although there is evidence to suggest that cortisol is typically elevated immediately following many types of stress and trauma but blunted after prolonged stress ( Judd et al., 2014 ; Miller et al., 2007 ). Kliewer (2006) did find that cortisol increased from pre-task to post-task (i.e., watching a video clip from the film Boyz 'n the Hood followed by a discussion) among youth who had been bullied, and in a more recent study, Kliewer and colleagues (2012) reported, among African American urban adolescents, that peer victimization was associated with greater sympathetic nervous system (fight or flight reaction) reactivity to a stress task (measured using salivary a-amylase, an enzyme that increases in saliva when the sympathetic nervous system is activated). However, in these studies, the immediate effect of being bullied on stress reactivity was not examined. In contrast, Ouellet-Morin and colleagues (2011) and Knack and colleagues (2011b) did not find an increase in cortisol in bullied youth following a psychosocial stress test but rather found a blunted pattern of response after the test had concluded (see Figures 4-1 and 4-2 ). In order to test whether, in the short-term, bullying produces an increase in cortisol, whereas in the long-term it is associated with a blunted cortisol response (as seen with other types of psychosocial stressors; Judd et al., 2014 ; Miller et al., 2007 ), a longitudinal study is needed to examine bullying chronicity and regulation of the HPA axis. The importance of this future work notwithstanding, there is evidence to support a finding that when stress becomes prolonged, the stress hormone system becomes hypofunctional and a blunted stress response results ( McEwen, 2014 ).

Cortisol reactivity for victimized and nonvictimized adolescents during the Trier Social Stress Test. SOURCE: Adapted from Knack et al. (2011b, Fig. 3, p. 5).

Cortisol responses to a psychosocial stress test (PST) in the total sample and according to maltreatment/bullying victimization. SOURCE: Adapted from Ovellet-Morin et al. (2011, Fig. 1, p. 14).

When stress becomes prolonged, the stress hormone system becomes hypofunctional and a blunted stress response results ( Knack et al., 2012a ; McEwen, 2014 ; Vaillancourt et al., 2013a ). That is, the elevation in cortisol in response to stress fails to occur. Scientists are not exactly sure how this happens, but evidence suggests that the stress system has shut itself down through “negative feedback.” Although on the surface this may seem to be beneficial, it is not. Cortisol has many functions and serves to regulate myriad biological systems; a blunted stress response compromises the orchestration of cortisol's biological functions. The critical importance of the massive over-activation of the stress system producing a blunted stress response is clinically relevant since it is associated with posttraumatic stress disorder and other psychiatric disorders ( Heim et al., 1997 ). It is also relevant for understanding an individual's inability to self-regulate and cope with stress.

Prolonged stress also disrupts the circadian or daily rhythm of cortisol, which is normally elevated in the morning and slowly decreases over the day to result in low levels at bedtime ( Barra et al., 2015 ). An altered circadian rhythm results not only in difficulty awaking in the morning but also in difficulty falling asleep at night. It can cause profound disruption in sleep patterns that can initiate myriad additional problems; sleep deficits are associated with problems with emotional regulation, learning, mood disorders, and a heightened social threat detection and response system ( McEwen and Karatsoreos, 2015 ). Recent research suggests that the consolidation of memories 2 one learns each day continues during sleep ( Barnes and Wilson, 2014 ; Shen et al., 1998 ). Sleep disturbances disrupt memory consolidation, and studies in animals suggest stress during learning engages unique neurochemical and molecular events that cause memory to be encoded by some unique mechanism ( Baratta et al., 2015 ; Belujon and Grace, 2015 ; McGaugh, 2015 ; Rau and Fanselow, 2009 ). Although victims of bullying have sleep problems ( Miller-Graff et al., 2015 ), causal relations between bullying, sleep disorders, learning/memory consolidation, and cortisol dysregulation have not been established. Indeed, these correlations between being a target of bullying and physiological problems may highlight important interactions between events and outcome, but it is also likely that unidentified variables might be the critical causal factors.

It is also noteworthy that the HPA axis showed heightened responsiveness during the peak ages of bullying ( Blakemore, 2012 ; Dahl and Gunnar, 2009 ; Romeo, 2010 ; Spear, 2010 ). For example, cortisol response characteristics in children are such that, when cortisol is activated, the hormonal response is protracted and takes almost twice as much time to leave the blood and brain compared to adults ( Romeo, 2010 , 2015 ). The circadian rhythm of cortisol also seems altered during early adolescence, most notably associated with morning cortisol levels, with levels increasing with age and pubertal development ( Barra et al., 2015 ). Animal models suggest that the extended cortisol response begins in pre-puberty and indicate that recovery from stressful events is more challenging during this age range ( Romeo, 2015 ).

Emotional regulation, including a person's ability to recover from a traumatic or stressful event, involves being able to regulate or normalize stress hormone levels. Before adolescence, children's ability to regulate their stress response can be greatly assisted by parents or other significant caregivers—a process referred to as “social buffering” ( Hostinar et al., 2014 ; Ouellet-Morin et al., 2011 , 2013 ). Specifically, it is well documented in the human and animal research literature that a sensitive caregiver or a strong support system can greatly dampen the stress system's response and actually reduce the amount of stress hormone released, as well as shorten the amount of time the stress hormones circulate within the body and brain. This results in dramatic decreases in stress-related behavior ( Gee et al., 2014 ; Hostinar et al., 2014 ). The social cues actually reduce stress by reducing the activation of the stress system, or HPA axis, at the level of the hypothalamus ( Hennessy et al., 2009 , 2015 ; Moriceau and Sullivan, 2006 ). The social stimuli that buffer children as they transition into adolescence appear to begin to have greater reliance on peers rather than on the caregiver ( Hostinar et al., 2015 ).

Other physiological effects of stress include the activation of the immune system by bullying-induced stress ( Copeland et al., 2014 ; McCormick and Mathews, 2007 ), and a cardiovascular blunting among individuals with a history of being bullied ( Newman, 2014 ). Other hormones and physiological mechanisms are also involved in the stress activation response. For example, cortisol is associated with an increase in testosterone, the male sex hormone associated with aggression in nonhuman animals and with dominance and social challenge in humans, particularly among boys and men ( Archer, 2004 ). In fact, in rodents the combined assessment of testosterone and cortisol provides more predictive value of behavioral variability ( McCormick and Mathews, 2007 ) compared to controls ( Márquez et al., 2013 ). In humans, there is increasing evidence supporting an interaction between testosterone and cortisol in the prediction of social aggression (see Montoya et al., 2012 ). In a study of 12-year-olds, Vaillancourt and colleagues (2009) found that testosterone levels were higher among bullied boys than nonbullied boys, but lower among bullied girls than nonbullied girls. The authors speculated that the androgen dynamics were possibly adrenocortical in origin, highlighting the need to examine testosterone and cortisol in consort. To date, researchers have only investigated cortisol response to being bullied ( Kliewer, 2006 ; Knack et al., 2011b ; Ouellet-Morin et al., 2011 ; Vaillancourt et al., 2008 ), and only one study has examined testosterone and peer victimization ( Vaillancourt et al., 2009 ). There are no studies examining these two important hormones together in relation to bullying perpetration or to being bullied.

Together, the research on both humans and animals suggests that stress is beneficial when it is experienced at low-to-moderate levels, whereas prolonged or repeated stress becomes toxic by engaging a unique neural and molecular cascade within the brain that is thought to initiate a different developmental pathway. Indeed, from animal models, brain architecture is altered by chronic stress, with amygdala activity being enhanced, hippocampal function impaired, and medial prefrontal cortex function being reduced, leading to increased anxiety and aggression and decreased capacity for self-regulation, as well as a more labile mood ( Chattarji et al., 2015 ; McEwen and Morrison, 2013 ; McEwen et al., 2015 ). This stress effect on the brain is particularly strong when experienced during adolescence, but it is even more pronounced if combined with early life adversity ( Gee et al., 2014 ; Hanson et al., 2015 ; Richter-Levin et al., 2015 ; Romeo, 2015 ; Sandi and Haller 2015 ). This could produce behavioral responses that become maladaptive by compromising emotional and cognitive functioning or perhaps it could produce adaptive behavior for a dangerous environment that results in socially inappropriate behavior.

Consequences of Bullying on Brain Function

Being a child or youth who is bullied changes behavior, and neuroscience research suggests this experience may also change the brain ( Bradshaw et al., 2012 ; Vaillancourt et al., 2013a ). The major technique used to monitor brain function in humans is functional magnetic resonance imaging (fMRI), which works by monitoring blood flow to indirectly assess the functioning of thousands of brain cells over an area of the brain. This technique has rarely been used on either the perpetrator or target of a bullying incident during this very particular social interaction, and for that reason little is known about whether or not the brain of a child who bullies or of a child who has been bullied is different before these experiences or is changed by them. These very specific studies are required before one can make definitive statements about the brain for this topic or for how this information might help develop novel interventions or prevention.

Additionally, it is important to consider two limitations for understanding fMRI. First, one cannot scan the brain of a child during the action of bullying or being a target of bullying. Instead, one must rely on the child staying perfectly still as the investigator tries to approximate one or two aspects of the complex experience that occur in this complicated behavioral interaction. For example, the fMRI task used during a brain imaging session might mimic social exclusion as one facet of bullying, without the full social and emotional context of the real bullying process. Although this is an important methodology, these results need to be assessed with caution at this time and not directly applied as an accepted scientific interpretation of bullying. Therefore, the examples used below to assess brain function rely not on monitoring actual instances of bullying behavior but on monitoring components of behaviors that are thought to occur during a bullying incident.

Second, fMRI monitors a large brain area, which is composed of many smaller brain areas, each of which is involved in many, many behaviors, many of which are not yet fully understood. Thus, it is difficult to determine why the brain area one is examining changed, since that brain area is involved in hundreds of diverse behaviors. For this reason, the results reviewed below need to be viewed as preliminary and should not be misinterpreted as explaining any aspect of the experience of bullying. Rather, these preliminary results highlight the importance of brain assessment before and after bullying experiences, including developing monitorable tasks that more closely approximate the bullying experience within the physical constraints of an immobile subject during an fMRI brain scan. The value of neuroscience is that it enables exploration of brain mechanisms controlling behavior that are not obvious from behavioral assessment.

Social Pain

Whereas there are no studies directly examining bullying using neural imaging techniques, there are several studies examining how the brain processes social pain. Social pain describes the “feelings of pain that follow the experiences of peer rejection, ostracism, or loss” ( Vaillancourt et al., 2013a , p. 242). Social pain is consistent with how people describe their feeling about being bullied. For example, one victim of bullying described the emotional toll of his experience by saying, “I feel like, emotionally, they [his bullies] have been beating me with a stick for 42 years” ( Vaillancourt et al., 2013a , p. 242).

Researchers have demonstrated that when people experience social pain, they activate regions in their brain similar to those activated when they experience physical pain ( Eisenberger, 2012 ; Eisenberger and Lieberman, 2004 ; Eisenberger et al., 2003 ; Kross et al., 2011 ; Vaillancourt et al., 2010a ). Specifically, the dorsal anterior cingulate cortex, which is part of the prefrontal cortex, seems to be implicated in the processing of both physical and social pain. The fact that physical and social pain have overlapping neural systems might explain why people tend to use physical pain metaphors (e.g., “It broke my heart when she called me ugly.”) when describing their experiences with being humiliated, oppressed, or rejected ( Eisenberger, 2012 ). Eisenberger and Leiberman (2004) noted that these fMRI results are correlations between pain and the anterior cingulate cortex and could reflect other functions of that brain region, such as detecting conflict or errors, different ideas or goals about the task, or individual differences in the task difficulty. In a recent fMRI study by Rudolph and colleagues (2016) , adolescent girls were socially excluded during a laboratory task (i.e., cyberball; Williams et al., 2000 ). Results indicated that activation of the social pain network—the dorsal anterior cingulate cortex, subgenual anterior cingulate cortex, and anterior insula—was associated with internalizing symptoms. Of note, this effect was particularly pronounced among adolescent girls with a history of peer victimization. 3

In addition to studies on social pain, there are some studies examining how the brains of children who had been bullied reacted subsequently to different stimuli. Experiences of being bullied can alter an individual's view of the world. While no brain imaging study has directly addressed this issue, a longitudinal study investigating the risk factors of depression found that being a child who was bullied at ages 11 and 12 was associated with a decreased response to reward in the medial prefrontal cortex at age 16, although it was unclear if these brain differences were present before the bullying experiences or developed after them ( Casement et al., 2014 ). The medial prefrontal cortex, which is a brain area involved in memory and learning, was found to be disrupted in children who have been bullied ( Vaillancourt et al., 2011 ). Because it also has countless other functions including decision making, risk taking, and conflict monitoring, disruption of this region compromises one's ability to interpret results with respect to bullying ( Euston et al., 2012 ; Vaillancourt et al., 2011 ).

In another fMRI study involving children, 10-12 years old, who were presented with a task that examined their response to negative feedback stimuli of emotional faces, greater and more extensive brain activation was found in the amygdala, orbitofrontal cortex, and ventrolateral prefrontal cortex of children who had been rejected by their peers, compared with children in a control group who had not been rejected by peers ( Lee et al., 2014 ), a condition that is highly correlated with being bullied by peers ( r = .57; Knack et al., 2012a ). The prefrontal cortex is a very large brain area with many subareas, all of which serve diverse functions in many different behaviors, not just executive function. Indeed, the prefrontal cortex processes pain, self-regulation, stress integration, and safety signals and has been implicated in psychiatric disorders, higher order learning, extinction (active process to suppress a memory), personality, social behavior, planning, decision making, and many other behaviors and percepts including social exclusion, social/physical pain, and empathy ( Casey and Jones, 2010 ; Spear, 2013 ). These few studies are consistent with other imaging studies demonstrating functional brain differences among individuals who were maltreated in childhood ( Lim et al., 2014 , 2015 ). Taken together, this work supports a finding that being exposed to such adversity during maturation has enduring effects on brain function, although additional research is needed to establish the parameters controlling these effects (and qualifying the generalization).

There is also evidence that stressful events, such as might occur with bullying experiences, impact emotional brain circuits, an inference that is supported by changes in amygdala architecture and function described earlier in animal models in adulthood but more robust changes in brain structure are produced by stress during early life and around adolescence ( Chattarji et al., 2015 ; McEwen and Morrison, 2013 ; McEwen et al., 2015 ). This point is critical because the stress system of adolescents seems to have a heightened sensitivity, and experiencing bullying can increase stress hormones ( Romeo, 2010 , 2015 ; Spear, 2013 ; Vaillancourt et al., 2011 ). Human brain scanning experiments suggest the prefrontal cortex is affected by stress through attenuating the connectivity to the hippocampus and amygdala, which are brain areas critical for emotional regulation and emotional memories ( Ganzel et al., 2008 ; Liston et al., 2009 ). Animal research shows that this connectivity loss is caused by stress-induced atrophy of the prefrontal cortex ( Radley et al., 2006 ), although this brain region does show the ability to recover once the stress has terminated ( Liston et al., 2009 ). One aspect of being a target of bullying is that the memory of the experience seems to be enduring; the unique function of the prefrontal cortex and emotional circuits during preadolescence and adolescence may provide insight into the enduring memories of being bullied. Specifically, one function of the prefrontal cortex is to help suppress memories that are no longer important or true. Typically, memories are not simply forgotten or unlearned. Rather, as we update information in our brain, the old memory is suppressed by overlaying a new memory to attenuate the old memory, an active brain process called extinction ( Milaid and Quirk, 2012 ). With respect to memories of trauma, of being bullied, or of experiencing a threat, the prefrontal cortex is important for attenuating (extinguishing) memories in emotional brain areas, such as the amygdala. Importantly, dramatic changes occur in the extinction system during adolescence, where fear extinction learning is attenuated relative to children and adults ( Pattwell et al., 2012 , 2013 ). This learning mode has been modeled in animals to understand how the process occurs in the adolescent brain ( Kim and Richardson, 2010 ; Nair and Gonzalez-Lima, 1999 ; Pattwell et al., 2012 ). The research suggests that around the time of adolescence, it is more difficult to decrease emotionally aversive memories, such as experiences of being bullied, than at other times in the life cycle. Furthermore, anxious teens (anxiety is sometimes comorbid with experience of being bullied) show even greater difficulties with processing extinction of fear memory ( Jovanovic et al., 2013 ).

In conclusion, the available evidence indicates that the brain functioning of individuals who are bullied is altered (see reviews by Bradshaw et al., 2012 ; Vaillancourt et al., 2013a ). However, it is difficult to ascertain fully what it means when fMRI scans detect an alteration in brain activity. In terms of understanding the prolonged and repeated stress associated with bullying, this research suggests that greater experience with being bullied and repeated exposure as a target of bullying produces a neural signature in the brain that could underlie some of the behavioral outcomes associated with being bullied.

Psychosocial Consequences

In this section, the committee examines what is known about the psychosocial consequences of being bullied. A common method of examining mental health issues separates internalizing and externalizing problems ( Sigurdson et al., 2015 ). Internalizing symptoms include problems directed within the individual, such as depression, anxiety, fear, and withdrawal from social contacts. Externalizing symptoms reflect behavior that is typically directed outwards toward others, such as anger, aggression, and conduct problems, including a tendency to engage in risky and impulsive behavior, as well as criminal behavior. Externalizing problems also include the use and abuse of substances.

Psychological problems are common after being bullied (see review by Hawker and Boulton, 2000 ) and include internalizing problems, such as depression, anxiety, and, especially for girls, self-harming behavior ( Kidger et al., 2015 ; Klomek et al., 2009 , 2015 ). There can also be subsequent externalizing problems, especially for boys (see review by McDougall and Vaillancourt, 2015 ). Rueger and colleagues (2011) found consistent concurrent association with timing of peer victimization and maladjustment. Both psychological and academic outcomes were particularly strong for students who experienced sustained victimization over the school year.

“And these are the kids that are at risk for anxiety and depression and bipolar disorder to begin with, and it almost seems like it's a cycle that makes it worse. So they are isolated and they are angry, they are fearful. Many of them end up severely depressed, attempting suicide, utilizing NSSIs [nonsuicidal self-injuries] for comfort. Some turn to gangs because that is the group that would accept them. So that's when we get involved and we have to start working backwards.”

—Quote from community-based provider discussing bullying during focus group (See Appendix B for additional highlights from interviews.)

Internalizing Problems

A robust literature documents that youth who are bullied often have low self-esteem and feel depressed, anxious, and lonely ( Juvonen and Graham, 2014 ). Data from developmental psychopathology research indicate that stressful life events can lead to the onset and maintenance of depression, anxiety, and other psychiatric symptoms and that for many youth, being bullied is a major life stressor ( Swearer and Hymel, 2015 ). Based on sociometric nominations, targets of bullying also are disliked by the general peer group ( Knack et al., 2012b ).

Several meta-analyses have specifically explored the relation between depression and being bullied at school ( Ttofi et al., 2011 ) and victimized by peers 4 ( Hawker and Boulton, 2000 ; Reijntjes et al., 2010 ). Individuals who had been cyberbullied reported higher levels of depression and suicidal ideation, as well as increased emotional distress, externalized hostility, and delinquency, compared with peers who were not bullied ( Patchin, 2006 ; Ybarra et al., 2006 ). Furthermore, severity of depression in youth who have been cyberbullied has been shown to correlate with the degree and severity of cyberbullying ( Didden et al., 2009 ).

Two meta-analyses found that across several different longitudinal studies using different study populations, internalizing emotional problems increases both the risk and the harmful consequences of being bullied ( Cook et al., 2010 ; Reijntjes et al., 2010 ). Internalizing problems can thus function as both antecedents and consequences of bullying ( Reijntjes et al., 2010 ; Vaillancourt et al., 2013b ). Although most longitudinal studies suggest that psychological problems result from being bullied (see review by McDougall and Vaillancourt, 2015 ) and meta-analyses ( Reijntjes et al., 2010 ; Ttofi et al., 2011 ) support this directionality, there is some evidence that for some youth, the temporal pattern begins with mental health problems ( Kochel et al., 2012 ; Vaillancourt et al., 2013b ).

In a large cohort of Canadian children followed every year from grade 5 to grade 8, Vaillancourt and colleagues (2013b) found that internalizing problems in grades 5 and 7 predicted increased self-reported bullying behavior the following year. They noted that these findings provide evidence for the “symptom-driven pathway” across time with increased internalizing problems predicting greater self-reported peer victimization. This “symptom-drive pathway” was noted from grade 5 to grade 6 and again from grade 7 to grade 8 and was consistent with other published work. For instance, Kochel et al. (2012) reported a symptom-driven pathway in which depressive symptoms predicted peer victimization 5 1 year later (grade 4 to grade 5 and grade 5 to grade 6) and argued that this pathway may result from depressed youth displaying “social deficits,” selecting “maladaptive relationships,” and/or displaying a behavioral style that is perceived poorly by the peer group ( Kochel et al., 2012 , p. 638). Vaillancourt and colleagues (2013b) have also argued that depressed youth could be more “treat sensitive.” That is, these youth may select information from their environment that is consistent with their negative self-opinion. The idea that certain individuals may be more sensitive to environmental cues or make more hostile interpretation of ambiguous social data has been well documented in the literature ( Crick and Dodge, 1994 ; Dodge, 1986 ). This work is consistent with studies showing that social information processing differs in children based on their experience with being bullied and that hypersensitivity can impact their interpretation of social behavior and their self-reports of subsequent incidents of being bullied ( Camodeca et al., 2003 ; Smalley and Banerjee, 2013 ).

Most longitudinal studies to date are of relatively short duration (i.e., less than 2 years) and focus on a narrow developmental period such as childhood or adolescence ( McDougall and Vaillancourt, 2015 ). Nevertheless, there are several recently published studies examining the long-term adult outcomes of childhood bullying. These studies indicate that being bullied does affect future mental health functioning, as reviewed in the following paragraphs.

Most long-term studies of childhood bullying have focused on links to internalizing problems in adulthood, demonstrating robust long-standing effects ( Gibb et al., 2011 ; Olweus, 1993b ; Sourander et al., 2007 ; Stapinski et al., 2014 ). For example, Bowes and colleagues (2015) examined depression in a large sample of participants who reported being the target of bullying at age 13 and found higher rates of depression at age 18 compared to peers who had not been bullied. Specifically, they reported that 14.8 percent of participants who reported being frequently bullied in childhood at age 13 were clinically depressed at age 18 ( OR = 2.96, 95% CI [2.21, 3.97]) and that the population attributable fraction was 29.2 percent, suggesting that close to a third of the variance in depression could be explained by being bullied in childhood ( Bowes et al., 2015 ).

In another longitudinal study using two large population-based cohorts from the United Kingdom (the ALSPAC Cohort) and the United States (the GSMS Cohort), Lereya and colleagues (2015) reported that the effects of childhood bullying on adult mental health were stronger in magnitude than the effects of being maltreated by a caregiver in childhood. Being bullied only (and not maltreated) placed individuals at higher risk for mental health difficulties than being maltreated only (and not bullied) ( OR = 1.6, 95% CI [1.1, 2.2] for ALSPAC cohort; OR = 3.8, 95% CI [1.8, 7.9] for GSMS cohort). Children who were bullied were more likely than maltreated children to be anxious ( OR = 4.9, 95% CI [2.0, 12.0] for GSMS cohort), depressed ( OR = 1.7, 95% CI [1.1, 2.7] for ALSPAC cohort), and to engage in self-harming behavior ( OR = 1.7, 95% CI [1.1-2.6] for ALSPAC cohort) in adulthood ( Lereya et al., 2015 ).

Similarly, Stapinski and colleagues (2014) found that adolescents who experienced frequent peer victimization 6 were two to three times more likely to develop an anxiety disorder 5 years later at age 18 than nonvictimized adolescents ( OR = 2.49, 95% CI [1.62, 3.85]). The association remained after adjusting for potentially confounding individual and family factors and was not attributable to diagnostic overlap with depression. Frequently victimized adolescents were also more likely to develop multiple internalizing problems in adulthood ( Stapinski et al., 2014 ). After controlling for childhood psychiatric problems or family hardship, Copeland and colleagues (2013) found that individuals who were bullied continued to have higher prevalence of generalized anxiety ( OR = 2.7, 95% CI [1.1, 6.3]).

These findings suggest that being bullied and internalizing problems such as depression are mutually reinforcing, with the experience of one increasing the risk of the other in a harmful cycle that contributes to the high stability of being both bullied and experiencing other internalizing problems. These studies also suggest that the long-term consequences of being bullied, which extend into adulthood, can be more severe than being maltreated as a child by a caregiver.

Externalizing Problems

Alcohol and drug abuse and dependence have been associated with being bullied as a child ( Radliff et al., 2012 ). A longitudinal study of adolescents found that those who reported being bullied were more likely to report use of alcohol, cigarettes, and inhalants 12 months later ( Tharp-Taylor et al., 2009 ), compared to those who did not report being bullied. More longitudinal research that tracks children through adulthood is needed to fully understand the link between being bullied and substance abuse (see review by McDougall and Vaillancourt, 2015 ).

Several studies show links between being bullied and violence or crime, especially for men ( Gibb et al., 2011 ; McGee et al., 2011 ; Sourander et al., 2007 , 2011 ). A meta-analysis by Reijntjes and colleagues (2011) that included studies with data on 5,825 participants showed that after controlling for externalizing symptoms at baseline, peer victimization—under which they included being the target of teasing, deliberate exclusion, and being the target of physical threats and malicious gossip—was associated over time with exhibiting externalizing problems such as aggression, truancy, and delinquency ( r = .14, 95% CI [.09, .19]). This research team also found that externalizing problems predicted changes in peer victimization over time ( r = .13, 95% CI [.04, .21]) and concluded that there is a bidirectional relationship between peer victimization and externalizing problems.

Psychotic Symptoms

Evidence from the broader research on childhood trauma and stress indicates that earlier adverse life experiences, such as child abuse, are associated with the development of psychotic symptoms later in life ( Institute of Medicine and National Research Council, 2014b ). Until recently, the association between bullying and psychotic symptoms has been understudied ( van Dam et al., 2012 ). Two recent meta-analyses support the association between bullying and the development of psychotic symptoms later in life ( Cunningham et al., 2015 ; van Dam et al., 2012 ). van Dam and colleagues (2012) conducted a meta-analysis of 14 studies to assess whether being bullied in childhood is related to the development of psychotic (either clinical or nonclinical) symptoms. (Nonclinical psychotic symptoms 7 place individuals at risk for the development of psychotic disorders ( Cougnard et al., 2007 ).) Results from the analyses of studies that examined the association between bullying and nonclinical symptoms (six studies) were more definitive (adjusted OR = 2.3; 95% CI [1.5, 3.4]), with stronger associations when there was an increased frequency, severity, and persistence of bullying ( Cougnard et al., 2007 ). Although some research has found this association, a recent longitudinal study from New Zealand found that the link between bullying and the development of psychosis later in life is likely not causal but instead reflects the fact that individuals who display disordered behaviors across childhood and adolescences are more likely to become bullying targets ( Boden et al., 2016 ) An analysis of studies that examined the association between bullying and psychosis in clinical samples was inconclusive ( van Dam et al., 2012 ).

A recent meta-analysis conducted by Cunningham and colleagues (2015) examined ten European prospective studies, four from the Avon Longitudinal Study of Parents and Children. This analysis found that individuals who were bullied were more than twice as likely to develop later psychotic symptoms, compared to those who were not bullied ( OR = 2.1, 95% CI [1.1, 4.0]). These results were consistent in all but one of the studies included in the meta-analysis. More longitudinal research is needed to more fully understand the mechanisms through which trauma such as bullying may lead to the development of psychotic symptoms ( Cunningham et al., 2015 ; van Dam et al., 2012 ). Importantly, this research will need to be prospective and examine the development of bullying and psychotic symptoms in order to truly identify the temporal priority. The inclusion criteria for the Cunningham and colleagues (2015) meta-analysis included that the study had to be prospective and had to include a measure of psychosis and that bullying needed to be reported before the age of 18. Although the authors stated that “bullying appears to cause later development of psychosis,” such a conclusion requires that mental health functioning be assessed early and over time, as it is possible that premorbid characteristics may make individuals targets for poor peer treatment (see Kochel et al., 2012 ; Vaillancourt et al., 2013b , regarding depression leading to peer victimization).

Academic Performance Consequences

A growing literature has documented that targets of bullying suffer diminished academic achievement whether measured by grades or standardized test scores ( Espelage et al., 2013 ; Nakamoto and Schwartz, 2010 ). Cross-sectional research indicates that children who are bullied are at increased risk for poor academic achievement ( Beran, 2009 ; Beran and Lupart, 2009 ; Beran et al., 2008 ; Glew et al., 2005 ; Neary and Joseph, 1994 ; see also meta-analysis by Nakamoto and Schwartz, 2010 ) and increased absenteeism ( Juvonen et al., 2000 ; Kochenderfer and Ladd, 1996 ; Vaillancourt et al., 2013b ).

The negative relation between being bullied and academic achievement is evident as early as kindergarten ( Kochenderfer and Ladd, 1996 ) and continues into high school ( Espinoza et al., 2013 ; Glew et al., 2008 ). In a 2-week daily diary study with ninth and tenth grade Latino students, Espinoza and colleagues (2013) reported that on days when adolescents' reports of being bullied were greater than what was typical for them, they also reported more academic challenges such as doing poorly on a quiz, test, or homework and felt like less of a good student. Thus, even episodic encounters of being bullied can interfere with a student's ability to concentrate on any given day. In a cross-sectional study of more than 5,000 students in grades 7, 9, and 11, Glew and colleagues (2008) found that for every 1-point increase in grade point average (GPA), the odds of being a child who was bullied (versus a bystander) decreased by 10 percent. However, due to the cross-sectional nature of this study, this association does not establish whether lower academic achievement among children who were bullied was a consequence of having been bullied.

Several short-term (one academic year) longitudinal studies indicate that being bullied predicts academic problems rather than academic problems predicting being a target of bullying ( Kochenderfer and Ladd, 1996 ; Schwartz et al., 2005 ). Given the impairments in brain architecture associated with self-regulation and memory in animal models and the currently limited imaging data in human subjects, this is a reasonable inference, although reverse causation is possible. For instance, early life abuse and neglect impair these same abilities, lower self-esteem, and may make an individual more likely to be a target of bullying. In one of the few longitudinal studies to extend beyond one year, Juvonen and colleagues (2011) examined the relation between victimization 8 and academic achievement across the three years of middle school. Academic adjustment was measured by both year-end grades and teacher reports of engagement. These authors found that more self-reported victimization was related to lower school achievement from sixth to eighth grade. For every 1-unit increase in victimization (on a 1-4 scale), GPA declined by 0.3 points.

Other short-term longitudinal studies found similar results. For example, Nansel and colleagues (2003) found that being bullied in a given year (grade 6 or 7) predicted poor academic outcomes the following year, after controlling for prior school adjustment and if they were previously targets of bullying or not. Similarly, Schwartz and colleagues (2005) reported a negative association for third and fourth grade children between victimization 9 and achievement 1 year later. In addition, Baly and colleagues (2014) found that the cumulative impact of being bullied over 3 years from sixth grade to eighth grade had a negative impact on GPA and standardized test scores.

However, other studies have not found such associations. For instance, Kochenderfer and Ladd (1996) found no relation between being bullied and subsequent academic achievement in their study of students assessed in the fall and spring of kindergarten, nor did Rueger and Jenkins (2014) in their study of seventh and eighth graders assessed in the fall and spring of one academic year. Feldman and colleagues (2014) also reported no association between being a target of bullying and academic achievement in their 5-year longitudinal study of youth ages 11-14. Poor academic performance can also be a predictor of peer victimization ( Vaillancourt et al., 2013b ). The authors found that poor writing performance in third grade predicted increased bullying behavior in fifth grade that was stable until the end of eighth grade.

The longitudinal associations between peer victimization and school attendance are also equivocal, with some showing positive associations ( Baly et al., 2014 ; Buhs et al., 2006 ; Gastic, 2008 ; Kochenderfer and Ladd, 1996 ; Smith et al., 2004 ) and others not finding a statistically significant association ( Forero et al., 1999 ; Glew et al., 2008 ; Rueger et al., 2011 ; Vaillancourt et al., 2013b ). 10

In summary, there have been a number of cross-sectional and longitudinal studies that have provided support for a relation between being bullied and increased risk for poor academic achievement. However, given the inconsistent results found with longitudinal studies, more research is warranted in this area to more fully ascertain the relation between being bullied and academic achievement over time.

• CONSEQUENCES FOR INDIVIDUALS WHO BULLY

There is evidence that supports a finding that individuals who bully others have contradictory attributes ( Institute of Medicine and National Research Council, 2014a ; Vaillancourt et al., 2010b ). Research suggests that there are children and adolescents who bully others because they have some form of maladjustment ( Olweus, 1993a ) or, as mentioned in Chapter 3 , are motivated by establishing their status in a social network ( Faris and Ennett, 2012 ; Rodkin et al., 2015 ; Sijtsema et al., 2009 ; Vaillancourt et al., 2003 ). Consequently, the relation between bullying, being bullied, acceptance, and rejection is complex ( Veenstra et al., 2010 ). This complexity is also linked to a stereotype held by the general public about individuals who bully. This stereotype casts children and youth who bully others as being high on psychopathology, low on social skills, and possessing few assets and competencies that the peer group values ( Vaillancourt et al., 2010b ). Although some occurrence of this “stereotypical bully” or “classic bully” is supported by research ( Kumpulainen et al., 2001 ; Olweus, 1993a ; Sourander et al., 2007 ), when researchers consider social status in relation to perpetration of bullying behavior, a different profile emerges. These studies suggest that most children and youth who bully others wield considerable power within their peer network and that high-status perpetrators tend to be perceived by peers as being popular, socially skilled, and leaders ( de Bruyn et al., 2010 ; Dijkstra et al., 2008 ; Peeters et al., 2010 ; Thunfors and Cornell, 2008 ; Vaillancourt et al., 2003 ). High-status bullies have also been found to rank high on assets and competencies that the peer group values such as being attractive or being good athletes ( Farmer et al., 2003 ; Vaillancourt et al., 2003 ); they have also been found to rank low on psychopathology and to use aggression instrumentally to achieve and maintain hegemony (for reviews, see Rodkin et al., 2015 , and Vaillancourt et al., 2010b ). Considering these findings of contrasting characteristics of perpetrators of bullying behavior, it makes sense that the research on outcomes of perpetrating is mixed. Unfortunately, most research on the short- and long-term outcomes of perpetrating bullying behavior has not taken into account this heterogeneity when considering the impact to children and youth who have bullied their peers.

Psychosomatic Consequences

Findings from cross-sectional studies that reported data on individuals who bullied others have shown that these individuals are at risk of developing psychosomatic problems ( Gini, 2008 ; Srabstein et al., 2006 ). Gini and Pozzoli (2009) conducted a meta-analysis to test whether children involved in bullying behavior in any role are at risk for psychosomatic problems. They included studies ( n = 11) that examined the association between bullying involvement and psychosomatic complaints in children and adolescents between the ages of 7 and 16. The studies included in the meta-analysis used self-report questionnaires; reports from peers, parents, or teachers; and clinical interviews that resulted in a clinical rating of the subject's behaviors and health problems. The included studies also had enough information to calculate effect sizes. An analysis of six studies that met the selection criteria revealed that children who bully had a higher risk ( OR = 1.65, 95% CI [1.34, 2.04]) of exhibiting psychosomatic problems than their uninvolved peers.

This meta-analysis was limited because of its inclusion of cross-sectional and observational studies. Such studies do not allow firm conclusions on cause and effect; hence, the association between bullying perpetration and psychosomatic problems may be difficult to interpret. The methodologies used in the studies make them susceptible to bias and misclassification due to the reluctance of individuals who bully to identify themselves as perpetrators of bullying behavior. Also, the different forms of victimization included in the underlying studies were not reported in this meta-analysis. Additional research is needed to examine the involvement in perpetrating bullying behavior and its short- and long-term psychosomatic consequences.

Psychotic Problems

Using a population-based cohort study, Wolke and colleagues (2014) examined whether bullying perpetration and being a target of bullying in elementary school predicted psychotic experiences 11 in adolescence. The authors assessed 4,720 individuals between the ages of 8 and 11 who were involved in bullying either as perpetrators or targets. At age 18, suspected or definite psychotic experiences were assessed using semistructured interviews. After controlling for the child's gender, intelligence quotient at age 8, and childhood behavioral and emotional problems, the researchers found that both individuals who are bullied (child report at age 10: OR = 2.4, 95% CI [1.6, 3.4]; mother report: OR = 1.6, 95% CI [1.1, 2.3]) and individuals who bullied others (child report at age 10: OR = 4.9, 95% CI [1.3, 17.7]; mother report: OR = 1.2, 95% CI [0.46, 3.1]) had a higher prevalence of psychotic experiences at age 18. The authors concluded that “involvement in any role in bullying may increase the risk of developing psychotic experiences in adolescence” ( Wolke et al., 2014 , p. 2208).

In summary, several studies have focused on the consequences of bullying for individuals who are bullied and have also reported more broadly on consequences for perpetrators of aggressive behavior (see Gini and Pozzoli, 2009 ; Lereya et al., 2015 ; Reijntjes et al., 2010 ; Ttofi et al., 2011 ), but the consequences of bullying involvement for individuals who perpetrate bullying behavior have been rarely studied to date. That is, although there is a rich literature on aggressors and the outcomes of being aggressive, there are few studies examining bullying perpetration specifically, taking into account the power imbalance, repetition, and intentionality that differentiates aggression from bullying from other forms of peer aggression. As discussed in Chapter 2 , the available research on the prevalence of bullying behavior focuses almost entirely on the children who are bullied. More research, in particular longitudinal research, is needed to understand the short- and long-term physical health, psychosocial, and academic consequences of bullying involvement on the individuals who have a pattern of bullying others, when those individuals are distinguished from children who engage in general aggressive behavior.

• CONSEQUENCES FOR INDIVIDUALS WHO BULLY AND ARE ALSO BULLIED

Individuals who bully and are also bullied experience a particular combination of consequences that both children who are only perpetrators and children who are only targets also experience, such as comorbidity of both externalizing and internalizing problems, negative perception of self and others, poor social skills, and rejection by the peer group. However, at the same time this combination of roles in bullying is negatively influenced by the peers with whom they are interacting ( Cook et al., 2010 ). After controlling for adjustment problems existing prior to incidents of bullying others or being bullied, a nationally representative cohort study found that young children who have been both perpetrators and targets of bullying tended to develop more pervasive and severe psychological and behavioral outcomes than individuals who were only bullied ( Arseneault et al., 2006 ).

Adolescents who were involved in cyberbullying as both perpetrators and targets have been found to be most at risk for negative mental and physical health consequences, compared to those who were only perpetrators, those who were only targets, or those who only witnessed bullying ( Kowalski and Limber, 2013 ; Nixon, 2014 ). For example, the results from a study by Kowalski and Limber (2013) that examined the relation between children's and adolescents' experiences with cyberbullying or traditional bullying and outcomes of psychological health, physical health, and academic performance showed that students who were both perpetrators and targets had the most negative scores on most measures of psychological health, physical health, and academic performance, when compared to those who were only perpetrators, only targets, or only witnesses of bullying incidents.

Wolke and colleagues (2001) examined the association of direct and relational bullying experience with common health problems and found that students ages 6-9 who bullied others and were also bullied by others had more physical health symptoms than children who were only perpetrators or were not involved in bullying behavior. Hunter and colleagues (2014) evaluated whether adolescents who were involved in bullying experienced sleep difficulties more than adolescents who were not involved. They analyzed surveys that were originally collected on behalf of the UK National Health Service and had been completed by adolescents ages 11-17. Controlling for gender, school-stage, socioeconomic status, ethnicity, and other factors known to be associated with sleep difficulties—alcohol consumption, tea or coffee consumption, and illegal drug use—the authors found that individuals who were both perpetrators and targets in bullying incidents were almost three times more likely ( OR = 2.90, 95% CI [1.17, 4.92]) to experience these sleep difficulties, compared to uninvolved young people. Additional research is needed to identify the mechanisms underlying short- and long-term physical health outcomes of individuals who bully and are also bullied.

There is evidence that individuals who are both perpetrators and targets of bullying have the poorest psychosocial profile among individuals with any involvement in bullying behavior; their psychosocial maladjustment, peer relationships, and health problems are similar to individuals who are only bullied, while their school bonding and substance use is similar to individuals who are only perpetrators ( Graham et al., 2006 ; Nansel et al., 2001 , 2004 ). Individuals who both bully and are also bullied by others experience a greater variety of both internalizing and externalizing symptoms than those who only bully or those who are only bullied ( Kim et al., 2006 ).

Some meta-analyses have examined the association between involvement in bullying and internalizing problems in the school-age population and concluded that that individuals who are both perpetrators and targets of bullying had a significantly higher risk for psychosomatic problems than individuals who were only perpetrators or who were only targets ( Gini and Pozzoli, 2009 ; Reijntjes et al., 2010 ). In their meta-analysis, Gini and Pozzoli (2009) reviewed studies that examined the association between involvement in bullying and psychosomatic complaints in children and adolescents. Analysis of a subgroup of studies ( N = 5) that reported analyses for individuals who bully and are also bullied by others showed that these individuals have a significantly higher risk for psychosomatic problems than uninvolved peers ( OR = 2.22, 95% CI [1.77, 2.77]).

Studies suggest that individuals who bully and who are also bullied by others are especially at risk for suicidal ideation and behavior, due to increased mental health problems (see Holt et al., 2015 , and Box 4-1 ).

Suicidality: A Summary of the Available Meta-Analyses.

Similar to individuals who bully, individuals who bully and are also bullied by others often demonstrate heightened aggression compared with non-involved peers. Compared to these other groups, they are by far the most socially ostracized by their peers, most likely to display conduct problems, and least engaged in school, compared with those who are either just perpetrators or just targets; they also report elevated levels of depression and loneliness ( Juvonen et al., 2003 ). Additional research is needed that examines the unique consequences of those children and youth characterized as “bully-victims” because often they are not separated out from “pure victims” (those who are bullied only) in studies. School shootings are a violent externalizing behavior that has been associated with consequences of bullying behavior in the popular media (see Box 4-2 for additional detail).

Bullying and School Shootings.

Several studies have examined the associations between bullying involvement in adolescence and mental health problems in adulthood and have found that individuals who have bullied others and have also been bullied had increased risk of high levels of critical symptoms of psychosis compared to non-involved peers ( Gini, 2008 ; Sigurdson et al., 2015 ). Research is limited in this area, and the topic warrants further investigation.

• CONSEQUENCES OF BULLYING FOR BYSTANDERS

Bullying cannot be viewed as an isolated phenomenon; it is intertwined within the particular peer ecology that emerges, an ecology constituted of social processes that serve particular functions for the individual and for the group ( Rodkin, 2004 ). Bullying frequently occurs in the presence of children and youth who are bystanders or witnesses. Research indicates that bullying can have significant adverse effects on these bystanders ( Polanin et al., 2012 ).

Bystanders have reported feelings of anxiety and insecurity ( Rigby and Slee, 1993 ) which stemmed, in part, from fears of retaliation ( Musher-Eizenman et al., 2004 ) and which often prevented bystanders from seeking help ( Unnever and Cornell, 2003 ). In a study to explore the impact of bullying on the mental health of students who witness it, Rivers and colleagues (2009) surveyed 2,002 students, ages 12-16 and attending 14 schools in the United Kingdom, using a questionnaire that included measures of bullying at school, substance abuse, and mental health risk. They found that witnessing bullying significantly predicted elevated mental health risks even after controlling for the effect of also being a perpetrator or victim (range of = .07 to .15). They also found that being a witness to the bullying predicted elevated levels (= .06) of substance use. Rivers and Noret (2013) found that, compared to students who were not involved in bullying, those who observed bullying reported more symptoms of interpersonal sensitivity (e.g., feelings of being hurt or inferior), helplessness, and potential suicide ideation.

In conclusion, there is very limited research available on the consequences of witnessing bullying for those children and youth who are the bystanders. Studies of bystander behavior have traditionally sought to understand their motives for participation in bullying ( Salmivalli, 2010 ), their roles ( Lodge and Frydenberg, 2005 ; Salmivalli et al., 1996 ), their behavior (either reinforcing the bully or defending the victim) in bullying situations ( Salmivalli et al., 2011 ), and why observers intervene or do not intervene ( Thornberg et al., 2012 ) from a social dynamic perspective, without exploring the emotional and psychological impact of witnessing bullying. More research is needed to understand these consequences.

MULTIPLE EXPOSURES TO VIOLENCE 12

One subpopulation of school-aged youth that may be at increased risk for detrimental short- and long-term outcomes associated with bullying victimization is poly-victims. Finkelhor and colleagues (2007) coined the terms “poly-victim” and “poly-victimization” to represent a subset of youth who experience multiple victimizations of different kinds—such as exposure to (1) violent and property crimes (e.g., assault, sexual assault, theft, burglary), (2) child welfare violations (child abuse, family abduction), (3) the violence of warfare and civil disturbances, and (4) being targets of bullying behavior—and who manifest high levels of traumatic symptomatology. The identification of a poly-victim is grounded not only in the frequency of the victimization but also in victimization across multiple contexts and perpetrators ( Finkelhor et al., 2007 , 2009 ).

Ford and colleagues (2010) determined that poly-victims were more likely to meet criteria for psychiatric disorder, including being two times more likely to report depressive symptoms, three times more likely to report posttraumatic stress disorder, up to five times more likely to use alcohol or drugs, and up to eight times more likely to have comorbid disorders, compared to youth that did not meet criteria for poly-victimization. Poly-victims often engaged in delinquent behavior, associated with deviant peers ( Ford et al., 2010 ), and were entrenched within the juvenile justice system ( Ford et al., 2013 ). Students who were poly-victims in the juvenile justice system reported higher levels of traumatic symptomatology ( Finkelhor et al., 2005 ). However, it is currently unclear whether being bullied plays a major or minor role in poly-victimization.

• MECHANISMS FOR THE PSYCHOLOGICAL EFFECTS OF BULLYING

In the following sections, the committee describes five potential mechanisms for the psychological effects of bullying behavior for both the children who are bullied and children who bully. These include self-blame, social cognition, emotional dysregulation, genetic predisposition to mental health outcomes and bullying, and telomere erosion. 13

One important mechanism for the psychological effects of bullying is how the targets of bullying construe the reason for their plight ( Graham, 2006 ). For example, a history of bullying and the perception of being singled out as a target might lead an individual to ask “Why me ?” In the absence of disconfirming evidence, some might come to blame themselves for their peer relationship problems. Self-blame and accompanying negative affect can then lead to many negative outcomes, including low self-esteem, anxiety, and depression ( Graham and Juvonen, 1998 ).

The adult rape literature (another form of victimization) highlights a correlation between experiencing rape and self-attributions that imply personal deservingness, labeled characterological self-blame, since they may lead to the person thinking of themselves as chronic victims ( Janoff-Bulman, 1979 ). From an attributional perspective, characterological self-blame is internal and therefore reflects on the self; it is stable and therefore leads to an expectation that harassment will be chronic; and it is uncontrollable, suggesting an inability to prevent future harassment. Attributing negative outcomes to internal, stable, and uncontrollable causes leads individuals to feel both hopeless and helpless ( Weiner, 1986 ). In contrast, behavioral self-blame (e.g., “I was in the wrong place at the wrong time”) implies a cause that is both unstable (the harassment is not expected to occur again) and controllable (there are responses in one's repertoire to prevent future harassment). Several researchers in the adult literature have documented that individuals who make characterological self-blaming attributions for negative outcomes cope more poorly, feel worse about themselves, and are more depressed than individuals who make attributions to their behavior (see Anderson et al., 1994 ). Research with early adolescents also revealed that characterological self-blame for academic and social failure resulted in heightened depression ( Cole et al., 1996 ; Tilghman-Osborne et al., 2008 ).

In the first attribution study focused specifically on bullying, Graham and Juvonen (1998) documented that sixth grade students with reputations as targets made more characterological self-blaming attributions for harassment than behavioral self-blaming attributions. Characterological self-blame, in turn, partly mediated the relationship between victim status and psychological maladjustment as measured by depression and social anxiety. Many studies since then have documented the relation between being targets of bullying, characterological self-blame, and maladjustment ( Graham et al., 2006 , 2009 ; Perren et al., 2012 ; Prinstein et al., 2005 ). Furthermore, bullied youth who endorsed characterological self-blame were likely to develop negative expectations about the future, which may also increase risk for continued bullying. For example, Schacter and colleagues (2014) reported that characterological self-blame endorsed in the fall of sixth grade predicted increases in reports of being bullied in the spring of sixth grade. Self-blame can then instigate psychological distress over time as well as increases in experiences of being bullied.

Such findings have implications for interventions targeted at bullied youth. The goal would be to change targets' maladaptive thoughts about the causes of their plight. For example, one could seek more adaptive attributions that could replace characterological self-blame. In some cases, change efforts might target behavioral explanations for being bullied (e.g., “I was in the wrong place at the wrong time”). In such cases, the goal would be to help targeted youth recognize that they have responses in their repertoire to prevent future encounters with harassing peers—that is, the cause is unstable and controllable ( Graham and Bellmore, 2007 ). External attributions also can be adaptive because they protect self-esteem ( Weiner, 1986 ). Knowing that others are also victims or that there are some aggressive youth who randomly single out unsuspecting targets can help lessen the tendency to self-blame ( Graham and Bellmore, 2007 ; Nishina and Juvonen, 2005 ). This approach of altering dysfunctional thoughts about oneself to produce changes in affect and behavior has produced a rich empirical literature on attribution therapy in educational and clinical settings (see Wilson et al., 2002 ). The guiding assumption of that research can be applied to alleviating the plight of targets of bullying.

Social Cognition

The most commonly cited models of social cognitive processes often connect back to work by Bandura (1973) , as well as to more recent conceptualizations by Crick and Dodge (1994) . These models have been applied to understanding aggressive behavior, but there has been less research applying these models to bullying behavior specifically. Related research by Anderson and Bushman (2002) on their general aggression model allows for a more focused understanding of the thoughts, feelings, and behaviors that contribute to the development of the negative outcome. This framework characterizes the inputs, the routes, the proximal processes, and the outcomes associated with aggressive behavior and either being targeted by or perpetrating bullying behavior ( Kowalski and Limber, 2013 ; Vannucci et al., 2012 ). Although these theories pertain to aggressive behavior more broadly, given that bullying is considered by most researchers to be a specific form of aggressive behavior, these broader theories may also improve understanding of the etiology and development of bullying. For example, research on hostile attribution bias suggests that aggressive youth are particularly sensitive to ambiguous and potentially hostile peer behaviors. Similar hypersensitivity to threat is also likely present in youth who bully.

Another particular element of social cognitive processes that has been linked with aggressive behavior is normative beliefs about aggressive retaliation ( Crick and Dodge, 1994 ; Huesmann and Guerra, 1997 ). Such beliefs include the belief that aggressive retaliation is normative, acceptable, or justified, given the context of provocation. There has been exploration of links between these beliefs and both reactive and proactive aggression. However, there has been relatively limited research specifically focused on bullying behavior. Yet, the available literature suggests that although it may seem as if targets of bullying would most likely endorse such attitudes, it is the perpetrators of bullying, including those who are involved in bullying as both a perpetrator and a target, who are mostly likely to support aggressive retaliation ( Bradshaw et al., 2009 , 2013 ; O'Brennan et al., 2009 ).

Emotion Dysregulation

Attempts to identify mechanisms linking bullying to adverse outcomes have largely focused on social-cognitive processes ( Dodge et al., 1990 ) as described above. More recently, researchers have begun to examine emotion dysregulation as an additional mechanism that explains associations between peer victimization and adverse outcomes. Emotion regulation refers to the strategies that people use to “increase, maintain, or decrease one or more components of an emotional response” ( Gross, 2001 , p. 215). One's choices among such strategies have implications not only for how robustly one responds to a stressor but also for how quickly one can recover from a stressful experience. Several studies have shown that emotion regulation difficulties—also called emotion dysregulation —increase youths' risk of exposure to peer victimization ( Hanish et al., 2004 14 ) and to bullying ( Mahady Wilton et al., 2000 ). However, it is important to understand whether peer victimization itself causes emotion regulation difficulties, which in turn predict the adverse outcomes that result from peer victimization (e.g., depression, aggressive behaviors).

Several lines of evidence support the hypothesis that emotion dysregulation may account for the relationship between peer victimization and adverse outcomes among adolescents. First, constructs that are related to peer victimization—including social exclusion ( Baumeister et al., 2005 ) and stigma ( Inzlicht et al., 2006 )—impair self-regulation. Second, chronic stress during childhood and adolescence leads to deficits in emotion regulation ( Repetti et al., 2002 ). Bullying has been conceptualized as a chronic stressor for children who are the perpetrators and the targets ( Swearer and Hymel, 2015 ), which in turn may disrupt emotion regulation processes. Third, laboratory-based studies have indicated that peer victimization is associated with emotion dysregulation (e.g., self-directed negative emotion, emotional arousal and reactivity) in the context of a novel peer interaction ( Rudolph et al., 2009 ) and in a contrived play-group procedure ( Schwartz et al., 1993 ). Over time, the effort required to manage the increased arousal and negative affect associated with peer victimization 15 may eventually diminish individuals' coping resources and therefore their ability to understand and adaptively manage their emotions, leaving them more vulnerable to adverse outcomes ( McLaughlin et al., 2009 ).

Several studies have provided empirical support for emotion dysregulation as a mediator of the association between peer victimization and adverse outcomes among adolescents. In one of the first longitudinal demonstrations of mediation, McLaughlin and colleagues (2009) , using data from a large, prospective study of adolescents (ages 11-14), showed that peer victimization at baseline predicted increases in emotion dysregulation four months later, controlling for initial levels of emotion dysregulation. In turn, emotion dysregulation predicted subsequent psychological distress (depressive and anxious symptoms), thereby mediating the prospective relationship between peer victimization (relational and reputational forms) and internalizing symptoms ( McLaughlin et al., 2009 ). Subsequent research from this same sample of adolescents showed that emotion dysregulation also mediated the prospective relationship between peer victimization and subsequent aggressive behavior ( Herts et al., 2012 ).

There is also emerging evidence that emotion regulation mediates relationships between bullying and adverse outcomes. In one example of this work, Cosma et al. (2012) examined associations between bullying and several emotion regulation strategies, including rumination, catastrophizing, and other-blaming, in a sample of adolescents. Although bullying was predictive for each of these emotion regulation strategies, only one (catastrophizing) mediated the relationship between being a target of bullying and subsequent emotional problems. Thus, while more research is needed, existing evidence suggests that both social-cognitive and emotion regulation processes may be important targets for preventive interventions among youths exposed to peer victimization and bullying.

Genetic Predisposition to Mental Health Outcomes and Bullying

Longitudinal research suggests that being the victim or perpetrator of bullying does not lead to the same pathological or nonpathological outcomes in every person ( McDougall and Vaillancourt, 2015 ). There are many factors that contribute to how a person responds to the experience of being victimized, with very strong links already established with life experiences, as reviewed above. Most studies examining heterogeneity in outcomes associated with bullying have focused on environmental characteristics, such as individual, family, and school-level features to explain why some individuals fare better or worse when involved with bullying ( Vaillancourt et al., in press ). For example, the moderating role of the family has been examined with results indicating that bullied children and youth with better home environments tend to fare better than those living with more complicated families ( Flouri and Buchanan, 2003 ; also see Chapter 3 of this report). Far fewer studies have examined the role of potential genetic influences as mediators between life experiences such as bullying and mental health outcomes. Identifying potential genetic influences is critical for improving understanding of the rich behavioral and epidemiological data already gathered. At the present time, evidence-based understanding of physiology and neuroscience is very limited, and insufficient data have been gathered to produce informed hypothesis testing.

There is a growing body of literature examining the relative role of genes' interaction with the environment in relation to experiences with trauma. However, there are fewer studies exploring potential relations between genes and being the target or perpetrator of bullying. At first glance these studies may appear to suggest that a person's involvement with bullying is predetermined based on his/her genetic profile. Yet, it is important to bear in mind that heritable factors are also associated with specific environments—meaning it is difficult to separate genetic effects from environmental effects. This is a phenomenon termed gene-environment correlations , abbreviated as rGE ( Brendgen, 2012 ; Plomin et al., 1977 ; Scarr and McCartney, 1983 ). For example, aggression, which is highly heritable ( Niv et al., 2013 ), can be linked to the selection of environments in different ways (for review, see Brendgen, 2012 ). Aggressive children may choose friends who are similar in their genetically influenced behavioral characteristic of being aggressive, and this type of selection influences the characteristics of their peer group ( Brendgen, 2012 , p. 420). This is an example of selective rGE. A child's genetically influenced characteristic to be aggressive can also produce a negative reaction from others, such as being disliked. This environmental variable of being rejected now “becomes correlated with the aggressive genotype” ( Brendgen, 2012 , p. 421). This is an example of evocative rGE. Another way that a person's genetic predisposition can be correlated with their environment is through a more passive process, called a passive rGE ( Brendgen, 2012 ). For example, aggressive parents may be more likely to live in high-crime neighborhoods, which influence the probability that their child will be associating with antisocial peers. These important rGE processes and confounds of interaction notwithstanding, it is worth mentioning that the research on the genetics of being a target or perpetrator of bullying is still in its infancy, and caution is needed when evaluating the results, as replication is much needed in this area. Before considering these studies, the committee first reviews the concept of how genetic differences influence behavior because it is important to clarify new concepts in this burgeoning area of science (see Box 4-3 ).

How Do Genes Influence Behavior?

With this backdrop in mind, the committee focused on twin studies of familial (family environment) versus genetic influence, gene by environment interaction, and a newer area of inquiry, epigenetics: the study of cellular and physiological phenotypic trait variations caused by external or environmental factors.

Twin Studies

Twin studies are routinely used to examine the relative influence of genetics and the environment on a particular phenomenon, such as being the target or perpetrator of bullying. In these studies, the causes of phenotypic variation (for example the variation in being a target or perpetrator of bullying) is separated into three components: (1) the additive genetic component or the heritable factor; (2) the shared environment component or the aspect of the environment twins share such as poor family functioning; and (3) the nonshared environment component or the aspect of the environment that is unique to each twin, such as the classroom if twins are in different classes.

Studies that decompose the unique effects of the environment and genetics on bullying behavior are best illustrated by two examples. Using data from the Environmental Risk (E-Risk) Longitudinal Twin Study, a study of high-risk 16 British twins reared together and apart, Ball and colleagues (2008) examined children's involvement in bullying and the genetic versus environmental contributions associated with their involvement. The twins in this study were assessed at ages 7 and 10 on their experiences with bullying, using teacher and parent reports. Results indicated that 73 percent of the variation in being the target of bullying and 61 percent of the variation in bullying perpetration were accounted for by genetic factors. In another study of Canadian twins reared together and assessed at age 7, using teacher and peer reports to assess peer victimization and aggression, Brendgen and colleagues (2008) found that for girls, 60 percent of the variation in aggression was accounted for by genetic factors and for boys, the variation estimate was 66 percent. For peer victimization, the Canadian study found that genetics did not play a role in the prediction of being targeted by peers. In fact, almost all of the variance was accounted for by environmental factors—29 percent of the variance in peer victimization was from the shared environment and 71 percent from the nonshared environment. The authors concluded that “genetic modeling showed that peer victimization is an environmentally driven variable that is unrelated to children's genetic disposition” ( Brendgen et al., 2008 , p. 455).

These two studies address the role genetics might play in the expression of aggressive behavior but conflict on the heritability of being a target of bullying. Most studies examining the heritability of externalizing problems, which includes studies on perpetrating aggression and bullying, report high heritability estimates. In fact, a recent meta-analysis found that aggression and rule-breaking were highly influenced by genetics, estimating the heritability rate at 41 percent ( Niv et al., 2013 ). Moreover, studies have found that the heritability estimates tend to be higher for more serious forms of antisocial behavior. For example, the heritability of psychopathy in 7-year-old British twin children reared together and apart and studied in the Twins Early Development Study was reported to be 81 percent ( Viding et al., 2005 ). However, estimates of the heritability of peer victimization vary across studies, as illustrated by the above results from Ball and colleagues (2008) contrasted with those from Brendgen and colleagues (2008) , and even within studies ( Brendgen et al., 2008 , 2013 ).

Brendgen and colleagues have since revised their assessment about the role genetics play in the prediction of being the target of bullying. In a more recent study, following the same children highlighted in the 2008 paper ( Brendgen et al., 2008 ) across three assessment periods (kindergarten, grade 1, and grade 4), Boivin and colleagues (2013) reported that at each grade, among twins who were reared together and apart, genetic factors accounted for a notable percentage of the variance in children's difficulties with peers. Peer difficulties were assessed as a latent factor derived from self-, teacher-, and peer-reports of peer victimization 17 and peer rejection. Specifically, in kindergarten and grade 1, 73 percent of the variance was accounted by genetic factors and in grade 4, genetic factors account for 94 percent of the variance in peer rejection and victimization.

There are several reasons for discrepancies between and within studies of the genetic contribution to bullying behavior. One reason is related to how peer victimization is assessed. Parent-, teacher-, peer-, and self-reports of bullying victimization have been shown to vary considerably across reporters ( Ostrov and Kamper, 2015 ; Patton et al., 2015 ; Shakoor et al., 2011 ); thus, the method used to assess involvement with bullying may lead to different results. Another reason for the differences may be related to development. The influence of the environment is expected to change as children age. Young children are particularly sensitive to family influences, while the influence of peers tends to matter more during adolescence ( Harris, 1995 ). Moreover, the type of environment a person is exposed to (i.e., harsh or nurturing) interacts with genes to produce a brain that is tailored to deal with the particular demands of that environment.

Taken together, the genetic studies reviewed suggest that aggression, which characterizes the perpetrator role in bullying ( Vaillancourt et al., 2008 ), might have heritable components, but the findings on being the target of bullying or other aggressive behavior are mixed. Thus, the role of genetic influences on both perpetrating and being a target of bullying requires more empirical attention before conclusions can be drawn.

Gene-by-Environment Interactions

Researchers also question whether specific genotypic markers of vulnerability (e.g., candidate genes) influence developmental outcomes in the face of adversity (i.e., environment). Importantly, there is some indication that genetics influences the mental health issues related to bullying highlighted above, such as depression and heightened aggression. For example, in gene-environment studies, candidate genes have been examined as moderators of the exposure to a toxic stressor such as child maltreatment and health outcomes such as depression. When the body experiences repeated bouts of stress that fail to resolve quickly, the heightened state of vigilance and preparedness depletes it of resources and the stress hormone cortisol begins to produce adverse effects. Specifically, prolonged stress disrupts brain functions and results in compromised decision making, faulty cognitive assessment, compromised learning and memory, and a heightened sense of threat that alters behavior ( Lupien et al., 2005 ; McEwen, 2014 ). There is evidence that the impact of changes in cortisol (either too high or too low) on learning may contribute, in part, to bullied children's decline in academic performance ( Vaillancourt et al., 2011 ), overeating/metabolic disorder, or emotional dysregulation, but this research is relatively new and needs to be explicitly explored within the context of bullying ( McEwen, 2014 ).

A paradigmatic example of this type of study is one by Caspi and colleagues (2003) , in which the moderating role of a functional polymorphism in the promoter region of the serotonin transporter gene 5-HTTLPR was examined in relation to exposure to maltreatment in childhood and depression in adulthood. Results indicated that depression rates were far greater among abused individuals if they had two copies of the short allele. 18 Among individuals with a long allele, depression rates were lower, suggesting that the long allele was protective, while the short allele was a risk factor for depression in the face of adversity. Although the exact role of this serotonin-related gene has been a subject of controversy, a meta-analysis concluded that overall, the results are consistent across studies ( Karg et al., 2011 ). Nevertheless, skepticism and controversy remain regarding studies of gene-environment interactions ( Dick et al., 2015 ; Duncan, 2013 ; Duncan and Keller, 2011 ; Duncan et al., 2014 ). This important debate notwithstanding, there is evidence that variations in genotype might moderate the relation between exposure to being bullied and health outcomes. For example, Sugden and colleagues (2010) found that bullied children who carried two short versions of the 5-HTTLPR gene were more likely to develop emotional problems than bullied children who carried the long allele. Importantly, this moderating effect was present even when pre-victimization emotional problems were accounted for statistically. In addition to this study, three other studies have demonstrated the moderating effect of the 5-HTTLPR gene in the bullying-health link ( Banny et al., 2013 ; Benjet et al., 2010 ; Iyer et al., 2013 ), with depression being worse for carriers of the short/short genotype (both alleles are the short version) than carriers of the short/long and long/long genotypes.

Although the evidence suggests that genotypes moderate the relation between being a target of bullying and poorer mental health functioning like depression, it is important to acknowledge that this relation is more complex. Indeed, some individuals may be particularly biologically sensitive to negative environmental influences such as being bullied, but this genetic vulnerability can also be linked to better outcomes in the context of a more supportive and enriched environment (see Vaillancourt et al., in press ). This phenomenon is termed differential susceptibility ( Belsky and Pluess, 2009 ; Boyce and Ellis, 2005 ). For example, in their study of 5 and 6-year old children, Obradovic and colleagues (2010) found that high stress reactivity as measured using respiratory sinus arrhythmia and salivary cortisol was linked to poorer socioemotional behavior in the context of being in an environment that was high in family adversity. In a context characterized by lower adversity, high stress-reactive children had more adaptive outcomes.

To the committee's knowledge, there are no studies that have examined bullying perpetration in relation to serotonin transporter polymorphisms, although there are studies that have examined this polymorphism in aggressive and non-aggressive children. For example, Beitchman et al. (2006) examined 5-HTTLPR in clinically referred children between the ages of 5 and 15 and found a positive association between the short/short genotype and aggression. In other studies, the short allele has been associated with problems with impulse control that includes the use of aggression ( Retz et al., 2004 ).

The moderating role of different candidate genes has also been examined in relation to exposure to childhood adversity and poorer developmental outcomes (see review by Vaillancourt et al., in press ). With respect to bullying, only a few studies have examined gene-environment interactions. In one study by Whelan and colleagues (2014) , harsh parenting was associated with increased peer victimization and perpetration, but this effect was not moderated by the Monoamine Oxidase A (MAOA) genotype. 19 In another longitudinal study, Kretschmer and colleagues (2013) found that carriers of the 4-repeat homozygous variant of the dopamine receptor D4 gene were more susceptible to the effects of peer victimization 20 on delinquency later in adolescence than noncarriers of this allele. Finally, in a large sample of post-institutionalized children from 25 countries, VanZomeren-Dohm and colleagues (2015) examined the moderating role of FKBP5 rs1360780 21 in the relation between peer victimization 22 and depression symptoms. In this study, gender was also found to be a moderator. Specifically, girls who had the minor genotype (TT or CT) were more depressed at higher levels of peer victimization, but less depressed at lower level of peer victimization than girls who had CC genotype. For boys, the CC genotype was associated with more symptoms of depression than girls with the same CC genotype who had been bullied.

It is clear that genetics influences how experiences contribute to mental and physical well-being, although the specifics of these gene-environment interactions are complex and not completely understood. Even though genes appear to modulate humans' response to being a target or a perpetrator of bullying behavior, it is still unclear what aspects of these experiences are interacting with genes and which genes are implicated to produce the variability in outcomes. Human genes and environment interact in a very complex manner: what biological events a particular gene influences can change at different stages of development. That gene therefore interacts with the environment in unique ways across the development timeline. These gene-environment interactions can be subtle and are under constant flux ( Lake and Chan, 2015 ). Knowing both the genes involved and the specific environment conditions is critically important to understanding these interactions; a simplistic view of either the genetic or environmental component, especially when considered in isolation from the behavioral literature, is unlikely to be productive.

Epigenetic Consequences

It is clear from the research reviewed here that there are a variety of pathways leading to adaptive and maladaptive endpoints and that these pathways can also vary within the “system” along with other conditions and attributes ( McDougall and Vaillancourt, 2015 , p. 300), including a person's genetic susceptibility. In this section, the committee focuses on studies examining how genetic susceptibility can make certain individuals more sensitive to negative environmental influences.

Although a person's DNA is fixed at conception (i.e., nonmalleable), environment can have a strong effect on how some genes are used at each of the stages of development. One way such changes in gene use and expression can occur is through an epigenetic effect, in which environmental events alter the portions of the genome that control when gene replication is turned on or off and what parts of a gene get transcribed ( McGowan et al., 2009 ; Roth, 2014 ). That is, while an individual's genetic information is critically important, the environment can help to increase or decrease how some genetic information is used by indirectly turning on or off some genes based on input received by somatic cells from the environment. Such epigenetic alterations have been empirically validated in several animal studies. For example, in one line of epigenetic studies, infant rat pups are raised with either low- or high-nurturing mothers or with mothers that treated the pups harshly. The researchers found that the type of maternal care received in infancy had a notable effect on the rats' subsequent ability to deal with stress ( McGowan et al., 2011 ; Roth and Sweatt, 2011 ; Weaver et al., 2004 ). The behavioral effects were correlated with changes in DNA methylation. 23 Epigenetic changes associated with gene-environment interactions is a new and exciting research area that provide a direct link between how our genes are read and is thought to enable us to pass our experiences to the next generations. It is helpful to think of genes as books in a library and epigenetics as placing a barrier in front of a book to decrease the chances it is read or providing easy access to the book. Thus far, research has found that certain epigenetic mechanisms are strongly correlated with different neurobehavioral developmental trajectories, including changes in vulnerability and resilience to psychopathology. How epigenetics relates to individual responses to being a target or perpetrator of bullying is not clear, but the research in related areas of behavior highlights an important emerging area for investigation.

Various epigenetic processes appear to interact with many changes in the brain produced by early life experiences, including not only the number and shape of brain cells but also how these cells connect to one another at synapses ( Hanson et al., 2015 ).

Regarding bullying, the committee identified only one study that has examined epigenetic changes. Specifically, Ouellet-Morin and colleagues (2013) found an increase in DNA methylation of the serotonin transporter gene for children who had been bullied by their peers but not in children who had not been bullied. These researchers also found that children with higher serotonin DNA methylation had a blunted cortisol response to stress, which they had previously shown changes as a consequence of poor treatment by peers ( Ouellet-Morin et al., 2011 ). That is, their 2011 study of twin children assessed at ages 5 and 10 found that being bullied was correlated with a change in how the body responds to stress. Bullied children displayed a blunted cortisol response to a psychosocial stress test. Because the design of the study involved an examination of identical twins who were discordant with respect to their experiences of being bullied (one twin was bullied while the other one was not), Ouellet-Morin and colleagues (2011) concluded that the effect could not be attributed to “variations in either genetic makeup, family environment, or other concomitant factors, nor could they be attributed to the twins' perceptions of the degree of stress experienced during the task” ( Vaillancourt et al., 2013a , p. 243).

In summary, it is important to note that there is no gene for being a perpetrator or a target of bullying behavior. Based on current knowledge of the genetics of complex social behavior, such as bullying, the genetic component of individual response is likely to involve multiple genes that interact with the environment in a complex manner. The current understanding of genetics and complex behaviors is that genes do not cause a behavior; gene-by-environment studies do not use the word “environment” the same way it is used in everyday language or even in traditional social psychology (as in Chapter 3 ). Rather, it is a construct used in a model to estimate how much variability exists in a given environment. This means that the same gene placed in different environments would yield very different percentages for gene-environment interactions. It is unclear how this information would inform our understanding of bullying.

Telomere Erosion Consequences

Epigenetic research has found that negative life experiences can alter the expression of a gene, which in turn, can confer a risk for poor outcomes. Research also suggests that the experience of being bullied is associated with telomere erosion. The end of each chromatid has been found to shorten as people age; this telomere “tail” also erodes as a function of engaging in unhealthy behavior such as smoking or being obese. Telomere erosion is also associated with certain illnesses such as cancer, diabetes, and heart disease ( Blackburn and Epel, 2012 ; Kiecolt-Glaser et al., 2011 ; Vaillancourt et al., 2013a ). Given these associations, scientists are now examining telomere erosion as a biomarker of stress exposure ( Epel et al., 2004 ), including the stress of being bullied by peers.

A recent longitudinal study by Shalev and colleagues (2013) examined telomere erosion in relation to children's exposure to violence, 24 a significant early-life stressor that is known to have long-term consequences for health. They found that exposure to violence, including being a target of bullying, was associated with telomere erosion for children assessed at age 5 and again at age 10. The sample for this study included 236 children recruited from the Environmental-Risk Longitudinal Twin Study ( Moffitt, 2002 ), 42 percent of whom had one or more exposures to violence. The study found that cumulative exposure to violence 25 is positively associated with accelerated telomere erosion in children, from baseline to follow-up, with potential impact for life-long health ( Shalev et al., 2013 ).

In this chapter, the committee reviewed and critically analyzed the available research on the physical health, psychosocial, and academic achievement consequences for children and youth who are bullied, for those who bully, for those who are both bullied and bullies, and for those who are bystanders to events of bullying. It also examined the potential mediating mechanisms of, and the genetic predisposition to, mental health outcomes associated with childhood and youth experiences of bullying behavior. Most studies are cross-sectional and thus provide only associations suggestive of a possible causal effect. This problem is most acute for studies based on anonymous self-report, in which both the independent variable (experience of bullying in one or more roles) and dependent variables (such as emotional adjustment) are data collected at the same time from sources subject to various forms of bias.

The limited amount of data from longitudinal and experimental research designs limits the ability to draw conclusions with respect to causality. Additional longitudinal studies, for example, could help establish that the negative consequences attributed to bullying were not present before the bullying occurred. But even this does not prove a causal effect, since bullying and the associated impairments might be products of some third factor. Below, the committee summarizes what is known about associations and consequences and identifies key conclusions that can be drawn from this evidence base.

• FINDINGS AND CONCLUSIONS

Finding 4.1: Individuals who both bully and are also bullied by others experience a greater variety of both internalizing and externalizing symptoms than those who only bully or are only bullied. Finding 4.2: Individuals who bully others are likely to experience negative emotional, behavioral, and mental health outcomes, though most research has not distinguished perpetration of bullying from other forms of peer aggression. Finding 4.3: A large body of research indicates that individuals who have been bullied are at increased risk of subsequent mental, emotional, and behavioral problems, especially internalizing problems. Finding 4.4: Studies of bystander behavior in bullying have rarely examined the emotional and psychological impact of witnessing bullying. Finding 4.5: Children and youth who are bullied subsequently experience a range of somatic disturbances. Finding 4.6: Social-cognitive factors (e.g., self-blame) and unsuccessful emotion regulation (i.e., emotion dysregulation) mediate relationships between bullying and adverse outcomes. Finding 4.7: There is evidence that stressful events, such as might occur with experiences of being bullied, alter emotional brain circuits. This potential outcome is critically in need of further investigation. Finding 4.8: Genetics influences how experiences contribute to mental and physical well-being, although the nature of this relationship is complex and not completely understood. Finding 4.9: Emerging evidence suggests that repeated exposure to bullying may produce a neural signature that could underlie some of the behavioral outcomes associated with being bullied. Finding 4.10: There are limited data on the physical health consequence of bullying for those individuals who are involved in bullying as targets, perpetrators, as both targets and perpetrators, and as bystanders. Finding 4.11: Poly-victims (individuals who are targets of multiple types of aggression) are more likely to experience negative emotional, behavioral, and mental health outcomes than individuals targeted with only one form of aggression. Finding 4.12: The long-term consequences of being bullied extend into adulthood and the effects can be more severe than other forms of being maltreated as a child. Finding 4.13: Individuals who are involved in bullying (as perpetrators, targets, or both) in any capacity are significantly more likely to contemplate or attempt suicide, compared to children who are not involved in bullying. It is not known whether bystanders are at increased risk of suicidal ideation or suicide attempts. Finding 4.14: There is not enough evidence to date to conclude that being the target of bullying is a causal factor for multiple-homicide targeted school shootings, nor is there clear evidence on how experience as a target or perpetrator of bullying, or the mental health and behavior issues related to such experiences, contribute to school shootings.

Conclusions

Conclusion 4.1: Further research is needed to obtain more in-depth evidence on the physical health consequences of being the target of bullying including neural consequences. Conclusion 4.2: Additional research is needed to examine mediators of short- and long-term physical health outcomes of individuals who are bullied. Evidence is also needed regarding how these outcomes vary over time for different groups of children and youth, why individuals with similar experiences of being bullied might have different physical health outcomes, and how physical and emotional health outcomes intersect over time. Conclusion 4.3: Although the effects of being bullied on the brain are not yet fully understood, there are changes in the stress response systems and in the brain that are associated with increased risk for mental health problems, cognitive function, self-regulation, and other physical health problems. Conclusion 4.4: Bullying has significant short- and long-term internalizing and externalizing psychological consequences for the children who are involved in bullying behavior. Conclusion 4.5: The data are unclear on the role of bullying as one of or a precipitating cause of school shootings. Conclusion 4.6: Individuals who both bully others and are themselves bullied appear to be at greatest risk for poor psychosocial outcomes, compared to those who only bully or are only bullied and to those who are not bullied. Conclusion 4.7: While cross-sectional studies indicate that children who are bullied are at increased risk for poor academic achievement relative to those who are not bullied, the results from longitudinal studies are inconsistent and warrant more research. Conclusion 4.8: Existing evidence suggests that both social-cognitive and emotion regulation processes may mediate the relation between being bullied and adverse mental health outcomes. Conclusion 4.9: Although genes appear to modulate humans' response to being either a target or a perpetrator of bullying behavior, it is still unclear what aspects of these experiences are interacting with genes and which genes are implicated to produce the variability in outcomes. Examining the role of genes in bullying in the context of the environment is essential to providing meaningful information on the genetic component of individual differences in outcomes from being a target or a perpetrator of bullying behavior.

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Somatization is “a syndrome of physical symptoms that are distressing and may not be fully explained by a known medical condition after appropriate investigation. In addition, the symptoms may be caused or exacerbated by anxiety, depression, and interpersonal conflicts, and it is common for somatization, depression, and anxiety to all occur together” ( Greenberg, 2016 ).

Consolidation of memory is a biological process where the information one learns is stabilized within neural circuits and placed into long-term memory through a complex orchestration of molecular-level change and gene activation within neurons.

Peer victimization was measured with a 21-item revised version of the Social Experiences Questionnaire. The measure assesses overt and relational victimization and frequency of different acts of victimization ( Rudolph et al., 2016 ).

Reijntjes and colleagues (2010, p. 244) defined peer victimization as taking “various forms, including direct bullying behaviors (e.g., teasing, physical aggression) as well as more indirect manifestations such as group exclusion or malicious gossip.” Hawker and Boulton (2000, p. 441) defined peer victimization as “the experience among children of being a target of the aggressive behavior of other children, who are not siblings and not necessarily age-mates.”

Peer victimization was measured using peer, self-, and teacher reports, including peer nominations, a four-item self-report victimization scale, and a six-item teacher report victimization scale ( Kochel et al., 2012 ).

Stapinski et al. (2014) used a modified version of the Bullying and Friendship Interview Schedule to assess self-reported peer victimization. This measure includes items on overt victimization, such as threats, physical violence, and relational victimization.

Nonclinical psychotic symptoms are symptoms that do not meet the clinical definition for those psychotic disorders associated with such symptoms.

Peer victimization was measured using a modified six-item version of the Peer Victimization Scale, which asks students to select a statement that is most like them. Higher scores indicated higher levels of peer victimization ( Juvonen et al., 2011 ).

Peer victimization was measured using a 16-item peer nomination interview and a teacher-completed Social Behavior Rating Scale ( Schwartz et al., 2005 ).

Peer victimization is used here to include the broader category of bullying, peer victimization, and bullying behavior.

Psychotic experiences included hallucinations (visual and auditory), delusions (spied on, persecution, thoughts read, reference, control, grandiosity), and experiences of thought interference (broadcasting, insertion, and withdrawal), and any unspecified delusions.

This section is adapted from Rose (2015 , pp. 18-21).

A telomere is the “segment at the end of each chromosome arm which consists of a series of repeated DNA sequences that regulate chromosomal replication at each cell division.” See http://ghr ​.nlm.nih.gov/glossary=telomere [December 2015]. Telomeres are associated with “chromosomal stability” and the regulation of “cells' cellular replicative lifespan” (Kiecolt-Glaser et al., 2011, p. 16).

Peer victimization was measured by a teacher-reported seven-item measure with items measuring broader peer victimization (Hanish et al., 2004).

Peer victimization was measured using the Revised Peer Experiences Questionnaire, which assesses overt, relational, and reputational victimization by peers (McLaughlin et al., 2009).

High risk was defined as a mother who had her first child at age 20 or younger ( Moffitt, 2002 ).

Peer victimization was assessed through teacher, peer, and self-ratings. Children were asked to circle photographs of two classmates who get called names by other children and who are often pushed or hit by other children.

An allele is an alternate form of the same gene. Except for the XY chromosomes in males, human chromosomes are paired, so a cell's genome usually has two alleles for each gene.

The MAOA genotype has been called the “warrior” gene because of its association with aggression in studies using surveys and observations ( McDermott et al., 2009 ).

Peer victimization was measured using a teacher-report 3-item scale that assessed relational victimization in the classroom ( Kretschmer et al., 2013 ).

The FKBP5 rs1360780 gene is associated with a number of different psychological disorders ( Wilker et al., 2014 ).

VanZomeren-Dohm and colleagues (2015 measured peer victimization using the MacArthur Health and Behavior Questionnaire Parent-Form, version 2.1, in which parents reported on their children's experiences of overt peer victimization.

DNA methylation is a heritable epigenetic mark involving the covalent transfer of a methyl group to the C-5 position of the cytosine ring by DNA methyltransferases (a family of enzymes that act on DNA). Cytosine is one of the four bases that occur in varying sequences to form the “code” carried by strands of DNA ( Robertson, 2005 ).

Exposure to violence included domestic violence, bullying victimization, and physical abuse by an adult.

Cumulative violence exposure was measured by an index that summed each type of violence exposure.

• Cite this Page Committee on the Biological and Psychosocial Effects of Peer Victimization: Lessons for Bullying Prevention; Board on Children, Youth, and Families; Committee on Law and Justice; Division of Behavioral and Social Sciences and Education; Health and Medicine Division; National Academies of Sciences, Engineering, and Medicine; Rivara F, Le Menestrel S, editors. Preventing Bullying Through Science, Policy, and Practice. Washington (DC): National Academies Press (US); 2016 Sep 14. 4, Consequences of Bullying Behavior.
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