title: Joint development of bullying and victimization in adolescence: relations to delinquency and self-harm.
abstract: OBJECTIVE
  To estimate trajectories of bullying and victimization in early to mid-adolescence, associations between the trajectories, and links with delinquency and self-harm.
  
  
  METHODS
  A total of 3,932 adolescents (50% boys) reported bullying (ages 14 to 16), victimization (ages 13 to 16), delinquency (age 16), and self-harm (age 16).
  
  
  RESULTS
  Two bullying trajectories (low/decreasing, high/increasing) and three victimization trajectories (low, high/decreasing, high/increasing) were identified. Over time, victimization increased the likelihood of involvement in bullying to a greater extent than bullying increased the likelihood of victimization. Boys and girls in the high/increasing bullying and the low or high/increasing victimization trajectories (i.e., the bullies and the bully-victims) were highest in mid-adolescent delinquency. Girls following the high/increasing bullying and high/increasing victimization trajectories (bully-victims) were the highest in mid-adolescent self-harm.
  
  
  CONCLUSIONS
  Youths who are victimized by their peers are at increased risk, in turn, of victimizing others. Sex-specific adjustment problems are associated with differing patterns of involvement in bullying and victimization among adolescents.
authors.affiliation: King's College London, Institute of Psychiatry, London, UK. Ted.Barker@iop.kcl.ac.uk
authors.forename: Edward D
authors.initials: ED
authors.lastname: Barker
authors.forename: Louise
authors.initials: L
authors.lastname: Arseneault
authors.forename: Mara
authors.initials: M
authors.lastname: Brendgen
authors.forename: Nathalie
authors.initials: N
authors.lastname: Fontaine
authors.forename: Barbara
authors.initials: B
authors.lastname: Maughan
mesh_terms: D000293:Adolescent; D000367:Age Factors; D000374:Aggression / Q000523:psychology*; D015897:Comorbidity; D019955:Conduct Disorder / Q000453:epidemiology* / Q000523:psychology; D019548:Crime Victims / Q000523:psychology / Q000706:statistics & numerical data*; D003430:Cross-Sectional Studies; D004291:Dominance-Subordination; D006801:Humans; D007604:Juvenile Delinquency / Q000523:psychology / Q000706:statistics & numerical data*; D012307:Risk Factors; D016728:Self-Injurious Behavior / Q000453:epidemiology / Q000523:psychology; D012737:Sex Factors; D013406:Suicide, Attempted / Q000523:psychology / Q000706:statistics & numerical data; D006113:United Kingdom