|Year : 2019 | Volume
| Issue : 2 | Page : 142-147
“Bullying in Incognito Mode”: The evolution of sibling bullying
Suhas Chandran1, SN Prakrithi2, KV Guru Prakash3, MD Kishor2
1 Department of Psychiatry, St. John's Medical College and Hospital, St. John's National Academy of Health Sciences, Bengaluru, India
2 Department of Psychiatry, JSS Medical College and Hospital, JSS Academy of Higher Education and Research, Mysuru, India
3 Department of Psychiatry, Command Hospital (Eastern Command), Kolkata, West Bengal, India
|Date of Submission||11-Jun-2018|
|Date of Decision||30-Jul-2018|
|Date of Acceptance||16-Feb-2019|
|Date of Web Publication||26-Jun-2019|
Dr. Suhas Chandran
Senior Resident, Department of Psychiatry, St. John's Medical College and Hospital, St. John's National Academy of Health Sciences, Bengaluru
Source of Support: None, Conflict of Interest: None
Sibling bullying, the lesser known counterpart of bullying is an unexplored entity, but the little research that exists has shown that it is almost as common as bullying by peers. Personality factors, interpersonal relationships, home environments and parental styles influence the development of bullying behaviors. The normalisation of certain actions by parents may lead to many bullying behaviours going unnoticed. In these cases, the feeling of security usually attached to the familial context is also lost in the victims. It has also been noted to spill over into other environments such as peer bullying and other modes, like cyber bullying. In addition to this arises the bully-victim situation, where the victim becomes the perpetrator, leading to a self propagating vicious cycle. The long term consequences include a higher risk for depression, anxiety, emotional dysregulation and even antisocial behaviour. In fact, multiple neurobiological correlates have also been established, such as alteration in hypothalamic-pituitary-adrenal axis activity, raised C-reactive protein levels and abnormal immune functions. To prevent these long term adverse effects, interventions should be initiated early, starting with parental guidance and sensitisation, peer support groups and anti bullying programs in schools.
Keywords: Bully-victim, neurobiological changes in bullying, sibling bullying, sibling bullying scales, sibling rivalry
|How to cite this article:|
Chandran S, Prakrithi S N, Guru Prakash K V, Kishor M D. “Bullying in Incognito Mode”: The evolution of sibling bullying. Indian J Soc Psychiatry 2019;35:142-7
|How to cite this URL:|
Chandran S, Prakrithi S N, Guru Prakash K V, Kishor M D. “Bullying in Incognito Mode”: The evolution of sibling bullying. Indian J Soc Psychiatry [serial online] 2019 [cited 2019 Sep 22];35:142-7. Available from: http://www.indjsp.org/text.asp?2019/35/2/142/261481
| Introduction|| |
Bullying has been variously defined as “a systematic abuse of power,” “an intentional aggressive behavior that is repeated against a victim who cannot readily defend himself or herself,” or “aggressive goal-directed behavior that harms another individual within the context of a power imbalance.” There has been considerable research in the recent past regarding traditional bullying and cyberbullying, but despite its ubiquity, sibling bullying remains a neglected issue.
Sibling relationships are one of the longest lasting relationships in a person's life and sibling experiences have a vital role in childhood and adolescent development. Sibling roles include that of a confidante, companion, role model, and social partner, and occasionally, they might even play out the role of a bully. Sibling bullying is defined as “a specific type of aggression aimed at dominating another person (a sibling) and at causing physical or psychological harm.” Wolke et al. have suggested a more comprehensive definition (adapted from Center for Disease Control and Prevention, Atlanta) as “any unwanted aggressive behavior (s) by a sibling that involves an observed or perceived power imbalance and is repeated multiple times or is highly likely to be repeated; may inflict harm or distress on the targeted sibling, including physical, psychological, or social harm.” It encompasses two modes of bullying (direct and indirect) as well as four types of bullying (physical, verbal, relational, and damage to property). Sibling rivalry, on the other hand, refers to “infrequent or singular acts of aggression” and when one child intends to repeatedly harm or humiliate another, that is bullying and it must be addressed. Sibling rivalry can occur between all siblings at one point or another, to a varying degree. It may be manifested as verbal/physical skirmishes, persistent demand for attention or frustration. It promotes healthy competition and equips the child with social and interpersonal skills. The parental skills of patience and understanding are necessary to handle sibling rivalry in a positive way. According to Wiehe, sibling rivalry entails age appropriate conflict behavior, which are isolated incidents and are reciprocal to sibling's or parents' behavior. These acts are also incident specific, with the only motivation being the individual's self-interest. It was found that competitiveness, be it for parental attention or desire to perform better than the other sibling in academic or nonacademic activities was also part of sibling rivalry, and this was more in siblings with smaller age gaps. Abuse/bullying, on the other hand, has an enduring pattern. It occurs in the context of secrecy and a power imbalance (where one sibling has an upper hand, either physically or emotionally). There is a component of victimization, and the dominant sibling does these acts specifically to hurt or embarrass the victim in some way.
Sibling bullying is extremely common, with almost 50% of children reported to be involved in the act every month. Smith noted that around 15%–50% reported victimization by siblings and 10%–40% reported perpetrating sibling bullying. In a study which compared sibling and peer bullying, participants reported that sibling bullying was more common, perpetrated and experienced more often than peer bullying. To the best of our knowledge, there are no studies conducted on sibling bullying in India or Asia. The terms sibling bullying, violence or abuse all come under the umbrella of negative sibling behaviors. Different studies have often used these terms interchangeably to explain similar behaviors. Gredler and Olweus, however, noted that aggression is a single act and might be between two individuals of equal power, whereas bullying comprised repeated acts associated with a power imbalance. Menesini et al. noted that the intentional nature (doing it specifically with the intent to cause harm), persistence (repeatedly persisting in harming behavior) and the imbalance of power differentiate bullying from aggression or conflict. The power imbalance in this context could be due to size, age or position/status of the bully over the victim, which makes the victim's defense difficult. In cyberbullying, the anonymity might negate this imbalance, but on the other hand, that itself can be a cause for apprehension, in that it is as of yet a threat of unknown quantity, through the victim's perspective.
| Etiology|| |
Multiple factors have been implicated in the formation of these behaviors, including personality factors, interpersonal relationships, and parenting styles. Wolke and Skew noted that male, socially withdrawn, easy to react individuals with emotional dysregulation, and poor coping skills increased the risk of victimization. Individuals with irritability, anxiousness, low agreeableness, and difficulty in adapting to new environments have relational and externalizing problems which can lead to bullying behaviors. Brody noted that children with highly active temperaments had four times more sibling conflict than active children did. Menesini et al. noted that children who experienced higher levels of conflict and lower levels of empathy, without warmth and support could perpetrate bullying in the family. Trait anger, defined as a tendency to become angry in various situations, has been found to have a positive relationship with peer bullying. A study by Tanrikulu and Campbell found that it is significantly associated with traditional sibling bullying as well. According to Furman and Buhrmester, the balance between the four dimensions of a sibling relationship, i.e., warmth, relative power/status, conflict and rivalry, influence negative behavior. Increase in conflict and rivalry result in antagonism, negative attitude toward each other and breed bullying behavior in the one who perceives differential parental treatment. It was found that participants in bullying had less attachment with both or either of their parents. These individuals have lower empathy and self-esteem, have a need for affirmation and respond with aggression, conflict, and more often engage in sibling bullying and also have a higher likelihood of victimization., Normalization by parents witnessing the sibling bullying is an attitude which significantly increases the incidence of bullying instances. Parenting styles contribute significantly to the prevalence of all types of bullying. Children raised in violent home environments, with parental abuse, destabilizing intra-familial relationships, low family cohesion, dysfunctional families with maltreatment and parental conflicts also expressed higher aggression toward siblings and peers both. Negative parental involvement and low parental support are also contributing factors. One study noted that victims were less likely to tell someone if they were exposed to coercive rearing techniques, possibly due to this indirectly validating aggression. This can also be explained by the attachment theory, where children develop internal working models based on their initial interactions with their primary caregivers. Overall, the behavior that may have the greatest impact on sibling bullying seems to be parental differentiation or favoritism. Based on the temperament a child having greater access to parental resources such as love, attention, and even material resources can evoke bullying behavior to maintain this favored position or on the flipside, this child can also be bullied by a sibling who wants to take away this position. Prevalence also increased with having actually experienced physical violence at the hands of parents, maternal disciplinary practices, and if the father frequently lost his temper. The number of siblings, and whether they were brothers or a mixture of brothers-sisters also had bearing in predicting bullying behavior. Step or lone parent households and having half-siblings increased the risk of victimization. Low-income families, household material deprivation, and low parental occupational prestige also increased the risk of sibling bullying. Unsafe, violent disorganized neighborhoods have higher bullying rates, as compared to safe, connected neighborhoods, which predicted less bullying and victimization. Exposure to violent video games, TV, films, media violence correlated with higher aggression, and antisocial behavior, thereby increasing the risk of both sibling and peer bullying.,
| Differences Seen in Gender and Birth Order|| |
There is considerable association between male gender and increased bullying behavior. A study by Menisini et al. found that having an older brother increased the risk of victimization. Brothers more commonly exhibit aggressive, hostile behaviors in contrast to sisters, who are usually found to be more affectionate and supportive in the sibling relationship dynamic. Furthermore, Rosenthal and Doherty noted that the most common pattern was girls being abused by boys, especially when the physical violence was severe (fractures, injury to skull). The birth order also seems to be an important factor, with first-born usually exhibiting more authoritative behavior toward younger siblings.
| Association of Sibling Bullying With Other Forms of Bullying|| |
In most instances, there is spill-over of similar violent, aggressive behaviors into multiple environments in the child's life, like home and school, a bully at home can also be a bully in school, which can be explained by the underlying personality factors, individual temperaments, familial conflicts, and harsh parenting., Tippett and Wolke in their study reported that sibling bullying was associated with peer bullying, and that the individual roles were also carried over into different settings, meaning victims of sibling bullying would end up being victims in peer bullying, and the bullies tended to remain bullies in both situations. A review by Tucker et al. showed similar findings, with 15% of both children and adolescents reporting victimization by both siblings and peers. Victimization by siblings was, therefore, an additional risk factor for victimization by peers. Sapouna et al. noted that 50% of children reporting sibling bullying also reported victimization in school. Duncan et al. noted the inverse was also true, that children who were bullied in school were also bullied in the home context by siblings. This is because behavioral structures learnt at home are transferred to other contexts. Children get exposed to coercion, then co-participate in deviant activities and without supervision, this will continue and increase the risk of anti-social behaviors. Social behaviors employed in the sibling interaction are transferred to other relationships. Therefore, sibling relationships significantly affect other contexts either positively or negatively. The victims at home learn that they are powerless against the perpetrator and assume submissive avoidant personalities in school also, which, in turn, increases the chances of peer bullying. Ensor et al. showed that children with sustained anti-social behavior toward their siblings were more likely to bully unfamiliar peers. Repetitive severe sibling conflicts have effect on peer bullying as well, as children without affection or warmth, negative sibling interactions are less accepted by peers. A significant difference between peer and sibling bullying, other than the obvious one of place setting, is that the group nature, usually present in school, is conspicuously absent in the home-family context. Here, the line between bully and victim often becomes blurred, with roles becoming interchangeable. At home, the bully might become the victim and vice versa, as the bully does not have the support of the pack at home. Another association with sibling bullying is the coexistence of cyber bullying, where sibling bullying also permeates into the cyberspace. Kowalski and Limber noted that cyber bullying was quite predominant, with 12% of victims and 16% of bully-victims reporting to being bullied through the internet by a sibling. Technology can cater a blanket of anonymity to the sibling bully. They can intentionally harm siblings and neutralize the effect of their victims' strategies of coping with bullying in traditional ways. Anonymity may also more importantly aid sibling bullies to escape attention and punishment from their parents for bullying at home. Sibling bullies can utilize technology to amplify the impact of the humiliation by encompassing a larger audience who are not confined to the household. Furthermore, obtaining digital materials for bullying purposes, including videos, shameful photos or be it even photoshopped images seems easier for siblings who share and spend most of their time together.
| Measurement Tools|| |
- The Sibling Bullying Scale and the Sibling Victimization Scale are modifications of the University of Illinois Bully Scale, used to measure and quantify bullying behavior perpetrated by the person and the University of Illinois Victimization Scale, used to assess whether the patient was a victim of bullying. They each contain nine questions, which are modified to relate to the family and home setup instead of the school environment
- The Sibling Inventory of Behavior is used to assess the relationship between the siblings. It is divided into two parts, each comprising 32 questions. The first part of the scale is about the person's perception of his/her sibling's behavior and the second half is used to assess their perception of themselves in relation to their siblings
- The Juvenile Victimization Questionnaire has questions based on a variety of victimizations. It covers 34 different forms of offenses, which are divided into five areas: Conventional crime, child maltreatment, peer and sibling victimization, sexual assault and witnessing and indirect victimization
- The Revised Olweus Bully/Victim Questionnaire consists of 36 questions and has a clear definition of what is considered bullying and distinguishes bullying and teasing. It assesses global measures of bullying and being bullied and also a specific measure which assesses the type of victimization.
| Role of Misconceptions|| |
These acts most often go unnoticed by the parents, who find it difficult to distinguish between rivalry and bullying. There are serious negative connotations attached to bullying, whereas sibling rivalry can also be a completely normal occurrence and may just be a way for children to assert themselves. “The kids are just roughhousing,” is a common misconception which can turn out to be a costly mistake because the victimized child now does not know who to turn to for support when he/she is being bullied by a sibling, who is a member of his own family. The family and the confinement of the home environment, which once considered a safe haven becomes just another scary place. “Boys will be boys” is yet another aphorism that people use to justify physical aggression in boys, considered natural by most societies. In addition to this, when cyber bullying is involved, it becomes that much harder to recognize, as the victims are rarely forthcoming about their problems and it is hardly manifest in most instances, unlike traditional bullying. This is especially so when it involves siblings, where the traditional bullying is itself missed by parents, let alone cyber bullying.
| The Outcomes and a Need for Early Intervention|| |
In many instances of bullying, the victim often starts retaliating, i.e., the bullied becomes the perpetrator. This can turn into a vicious cycle, which, unless aborted, can lead to significant negative consequences like dysregulation of mental health in both bullies and victims, leading to formation of various internalizing (social isolation, depression, anxiety, and self-harm) and externalizing behaviors (violent behavior, aggression, and carrying weapons), as well as social adjustment problems such as loneliness and social introversion. Perpetration and victimization can be considered part of the same continuum. One study noted that >50% of the bullies reported to being victims as well and more commonly seen in sibling bullying than peer bullying. This creates three distinctions, the pure bullies, who bully the sibling but are not bullied themselves; the pure victims, who are bullied but do not bully their siblings, and the bully-victims, who bully siblings at times and become victims at others. These groups are also associated with different levels of emotional dysregulation and behavioral problems, the problems being especially high in bully-victims engaging in physical and relational bullying. Furthermore, this “bully-victim” group was found to have poorer psychosocial functioning than the pure bullies or victims, showed higher rates of problem behavior, poorer academic performance, more depressive symptoms, and lower social competence. Toseeb et al. reported that children with autism spectrum disorder (ASD) had increased the risk of sibling victimization, specifically as bully-victim, indicating that children with ASD displayed higher reactive aggression, i.e., the autistic child had a higher risk of being bullied by his sibling, and he, in turn, would bully the offending sibling.
Bullying is not a cross-sectional event but has long-term complications. Bowes et al. conducted a longitudinal study where children were asked about bullying experiences by siblings at age twelve. These individuals were evaluated for mental illness at the age of 18, which revealed that they had a twice as high risk of depression, anxiety, and self-harm in early adulthood compared to children who were not bullied by siblings, the risk increasing proportionately with the severity of victimization. Another study revealed that children bullied by siblings were three times more likely to develop psychotic disorders such as schizophrenia in early adulthood, and those victimized by both siblings and peers had four times the odds as compared to nonbullied individuals. Copeland et al. found higher rates of agoraphobia, generalized anxiety, panic disorder in victims, with bully-victims exhibiting a higher risk of young adult depression and suicidality in addition to these problems, whereas, the bullies were at a higher risk of anti-social personality disorder in adulthood. It was also associated with substance use, delinquency, and aggression. Sibling bullying has also been associated with higher risk of poorer general health, slower recovery from illnesses, lower educational qualifications, and earned less than their nonbullied peers, especially noticed more so in bully-victims than pure victims. Pure bullies, on the other hand, were more likely to express anti-social behavior, charged for crime, burglary and illegal drug use, indicating that the adverse consequences of bullying pervaded all aspects of life such as social, financial, in addition to the medical consequences. Research into the prevalence of these effects in relation to sibling bullying specifically has not been carried out, but it is conceivable that sibling bullying would also have similar, if not poorer outcomes, as the emotional dysregulation occurring as a consequence of bullying would be the same irrespective of who perpetrated the actual act. The fact that it is a family member could cause further distress as the feeling of security which is associated with family gets lost in these situations.
Bullying has been known to increase stress responses, alters HPA activity, cause abnormal immune responses, and increase susceptibility to mental health problems. Being bullied leads to chronic increase in C-reactive protein (CRP) levels, which increases with further incidences of bullying, with victims having twice as high levels as bullies and bullies having lower than normal levels of CRP. Independently, increased CRP levels have been associated with generalized anxiety disorder, panic disorder, functional gastrointestinal disorders such as irritable bowel syndrome and depression.,, This further substantiates the increased incidence of mental illnesses in bullying.
| Intervention Strategies to Curb Sibling Bullying|| |
Recognizing that there is a problem is a crucial first step. It is especially important that interventions start at home, because of the frequent concurrence between sibling and peer bullying. Parents need to acknowledge it and encourage children to verbalize and resolve conflicts efficiently in a nonthreatening manner. Peer support groups, peer-helpers, and improving social support by involving family members will allow victims to confide in a trusted friend or family member about bullying incidences.
Schools form the cornerstone for addressing issues related to childhood bullying. Anti-bullying programs in school targeting students, parents, and teachers must give information about sibling bullying as well and also raise awareness about intervention methods for the same. In this context, schools can have a considerably higher impact than mental health professionals, as it is only the sporadic case that gets referred to the psychiatrist or psychologist.
Addressing the mental health concerns of victims like self-harm and depression forms an integral part of management along with genesis of empathy for the victim and assertiveness training. Mental health professionals should have a high degree of suspicion of the possibility of simultaneous sibling bullying in victims of peer bullying and vice versa. Specific questions about conflicts with siblings can bring to light bullying instances which would otherwise have gone unnoticed. The bully-victim group needs special attention, due to their poorer outcomes compared to pure bullies or victims. As Carl Jung rightly said, “The healthy man does not torture others-generally, it is the tortured who turn into torturers.” While there are intervention programs in place for schools and teachers in the handling of peer bullying, similar evidence-based programs for parents for handling sibling bullying is lacking and must be the focus of future research.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Rigby K. New Perspectives on Bullying. England: Jessica Kingsley Publishers; 2002.
Smith PK, Slee P, Morita Y, Catalano R, Junger-Tas J, Olweus D. The nature of school bullying: A cross national perspective. London: Routledge; 1999. p. 28-48.
Volk AA, Dane AV, Marini ZA. What is bullying? A theoretical redefinition. Dev Rev 2014;34:327-43.
Wolke D, Tippett N, Dantchev S. Bullying in the family: Sibling bullying. Lancet Psychiatry 2015;2:917-29.
Leung AK, Robson WL. Sibling rivalry. Clin Pediatr (Phila) 1991;30:314-7.
Wiehe VR. Sibling Abuse: Hidden Physical, Emotional, and Sexual Trauma. Sage: Thousand Oaks, California; 1997.
Smith PK. Bullying in schools: Thirty years of research. In: Monks C, Coyne I, editors. Bullying in Different Contexts. 1st ed. New York: Cambridge University Press; 2011. p. 36-60.
Hoetger LA, Hazen KP, Brank EM. All in the family: A retrospective study comparing sibling bullying and peer bullying. J Fam Violence 2015;30:103-11.
Gredler GR, Olweus D. Bullying at school: What we know and what we can do. Psychol Sch 2003;40:699-700.
Menesini E, Camodeca M, Nocentini A. Bullying among siblings: The role of personality and relational variables. Br J Dev Psychol 2010;28:921-39.
Butler D, Kift S, Campbell M. Cyber bullying in schools and the law: Is there an effective means of addressing the power imbalance. eLaw J 2009;16:84.
Wolke D, Skew AJ. Bullying among siblings. Int J Adolesc Med Health 2012;24:17-25.
Brody GH. Sibling relationship quality: Its causes and consequences. Annu Rev Psychol 1998;49:1-24.
Camodeca M, Goossens FA. Aggression, social cognitions, anger and sadness in bullies and victims. J Child Psychol Psychiatry 2005;46:186-97.
Tanrikulu I, Campbell MA. Sibling bullying perpetration: Associations with gender, grade, peer perpetration, trait anger, and moral disengagement. J Interpers Violence 2015;30:1010-24.
Furman W, Buhrmester D. Children's perceptions of the qualities of sibling relationships. Child Dev 1985;56:448-61.
Bar-Zomer J, Brunstein Klomek A. Attachment to parents as a moderator in the association between sibling bullying and depression or suicidal ideation among children and adolescents. Front Psychiatry 2018;9:72.
Eliot M, Cornell DG. Bullying in middle school as a function of insecure attachment and aggressive attitudes. Sch Psychol Int 2009;30:201-14.
Weihe VR. Sibling abuse. In: Henderson H, editor. Domestic Violence and Child Abuse Sourcebook. Detroit, Omnigraphics Incorporated; 2000. p. 409-92.
Wolke D, Skew AJ. Family factors, bullying victimisation and wellbeing in adolescents. Longitudinal Life Course Stud 2011;3:101-19.
Unnever JD, Cornell DG. Middle school victims of bullying: Who reports being bullied? Aggress Behav 2004;30:373-88.
Bowlby J. Attachment and Loss. Loss. Vol. 1. Nueva York: Basic Books; 1969.
Eriksen S, Jensen V. All in the family? family environment factors in sibling violence. J Fam Violence 2006;21:497-507.
Costello EJ, Angold A, Burns BJ, Stangl DK, Tweed DL, Erkanli A, et al.
The great smoky mountains study of youth. Goals, design, methods, and the prevalence of DSM-III-R disorders. Arch Gen Psychiatry 1996;53:1129-36.
Gentile DA, editor. Media Violence and Children. Westport, CT: Praeger; 2003.
Swearer SM, Espelage DL, Koenig B, Berry B, Collins A, Lembeck P. A social-ecological model of bullying prevention and intervention in early adolescence. In: Jimerson SR, Nickerson AB, Mayer MJ, Furlong MJ, editors. The Handbook of School Violence and School Safety: International Research and Practice. New Jersey: Lawrenxe Erlbaum Associates, Publishers; 2006.
Rosenthal PA, Doherty MB. Serious sibling abuse by preschool children. J Am Acad Child Psychiatry 1984;23:186-90.
Tippett N, Wolke D. Aggression between siblings: Associations with the home environment and peer bullying. Aggress Behav 2015;41:14-24.
Tucker CJ, Finkelhor D, Turner H, Shattuck AM. Sibling and peer victimization in childhood and adolescence. Child Abuse Negl 2014;38:1599-606.
Sapouna M, Wolke D, Vannini N, Watson S, Woods S, Schneider W, et al
. Individual and social network predictors of the short-term stability of bullying victimization in the United Kingdom and Germany. Br J Educ Psychol 2012;82:225-40.
Duncan RD. Peer and sibling aggression: An investigation of intra- and extra-familial bullying. J Interpers Violence 1999;14P: 871-86.
Snyder J, Bank L, Burraston B. The consequences of antisocial behavior in older male siblings for younger brothers and sisters. J Fam Psychol 2005;19:643-53.
Stauffacher K, DeHart GB. Crossing social contexts: Relational aggression between siblings and friends during early and middle childhood. J Appl Dev Psychol 2006;27:228-40.
Ensor R, Marks A, Jacobs L, Hughes C. Trajectories of antisocial behaviour towards siblings predict antisocial behaviour towards peers. J Child Psychol Psychiatry 2010;51:1208-16.
Kowalski RM, Limber SP. Electronic bullying among middle school students. J Adolesc Health 2007;41:S22-30.
Espelage DL, Holt MK. Bullying and victimization during early adolescence: Peer influences and psychosocial correlates. J Emot Abuse 2001;2:123-42.
Henderson SH. Adolescent siblings in stepfamilies: Family functioning and adolescent adjustment. Monogr Soc Res Child Dev 1999;64:26-49.
Hamby SL, Finkelhor D, Ormrod RK, Turner HA. The juvenile victimization questionnaire (JVQ): Administration and scoring manual. Durham, NH: Crimes against Children Research Center; 2004.
Olweus D. The Revised Olweus bully/Victim Questionnaire. University of Bergen, Research Center for Health Promotion; 1996.
Arseneault L, Bowes L, Shakoor S. Bullying victimization in youths and mental health problems: 'much ado about nothing'? Psychol Med 2010;40:717-29.
Duncan RD. Peer and sibling aggression: An investigation of intra-and extra-familial bullying. J Interpers Violence 1999;14:871-86.
Button DM, Gealt R. High risk behaviors among victims of sibling violence. J Fam Violence 2010;25:131-40.
Haynie DL, Nansel T, Eitel P, Crump AD, Saylor K, Yu K, et al
. Bullies, victims, and bully/victims: Distinct groups of at-risk youth. J Early Adolesc 2001;21:29-49.
Toseeb U, McChesney G, Wolke D. The prevalence and psychopathological correlates of sibling bullying in children with and without autism spectrum disorder. J Autism Dev Disord 2018;48:2308-18.
Bowes L, Wolke D, Joinson C, Lereya ST, Lewis G. Sibling bullying and risk of depression, anxiety, and self-harm: A prospective cohort study. Pediatrics 2014;134:e1032-9.
Dantchev S, Zammit S, Wolke D. Sibling bullying in middle childhood and psychotic disorder at 18 years: A prospective cohort study. Psychol Med 2018;48:2321-8.
Copeland WE, Wolke D, Angold A, Costello EJ. Adult psychiatric outcomes of bullying and being bullied by peers in childhood and adolescence. JAMA Psychiatry 2013;70:419-26.
Wolke D, Lereya ST. Long-term effects of bullying. Arch Dis Child 2015;100:879-85.
Bankier B, Barajas J, Martinez-Rumayor A, Januzzi JL. Association between C-reactive protein and generalized anxiety disorder in stable coronary heart disease patients. Eur Heart J 2008;29:2212-7.
Hoge EA, Brandstetter K, Moshier S, Pollack MH, Wong KK, Simon NM, et al.
Broad spectrum of cytokine abnormalities in panic disorder and posttraumatic stress disorder. Depress Anxiety 2009;26:447-55.
Plavšić I, Hauser G, Tkalčić M, Pletikosić S, Salkić N. Diagnosis of irritable bowel syndrome: Role of potential biomarkers. Gastroenterol Res Pract 2015;2015:490183.