title: Development of male proactive and reactive physical aggression during adolescence.
abstract: BACKGROUND
  Different developmental courses have been postulated for proactive and reactive aggression.
  
  
  OBJECTIVE
  Investigated the developmental course of proactive and reactive aggression in a large sample of adolescent boys from low socioeconomic areas.
  
  
  METHODS
  A dual group-based joint trajectory method was used to identify distinct trajectories as well as similarities and differences in intra-individual changes.
  
  
  RESULTS
  The trajectories for proactive and reactive aggression were similar: the majority of individuals followed infrequent and desisting trajectories. Contrary to expectations, very few adolescents followed trajectories of increasing proactive aggression. Reactive aggression was more common than proactive aggression. The overlap in trajectory group membership of individuals following trajectories of high peaking proactive and reactive aggression was nearly 100%. Across a period of 5 years, the boys on the high peaking trajectories were twice as likely to have affiliated with gangs.
  
  
  CONCLUSIONS
  The developmental courses of proactive and reactive aggression are similar during adolescence. Males who tend to frequently use one form of aggression throughout adolescence also tend to frequently use the other and are at an increased risk for contemporaneous delinquent lifestyles.
authors.affiliation: University of Montreal, Quebec, Canada. edward.dylan.barker@umontreal.ca
authors.forename: Edward D
authors.initials: ED
authors.lastname: Barker
authors.forename: Richard E
authors.initials: RE
authors.lastname: Tremblay
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Nagin
authors.forename: Frank
authors.initials: F
authors.lastname: Vitaro
authors.forename: Eric
authors.initials: E
authors.lastname: Lacourse
mesh_terms: D000293:Adolescent; D000367:Age Factors; D000374:Aggression / Q000523:psychology*; D006801:Humans; D007206:Individuality; D007604:Juvenile Delinquency / Q000523:psychology / Q000706:statistics & numerical data; D008019:Life Style; D008137:Longitudinal Studies; D008297:Male; D015233:Models, Statistical; D010379:Peer Group; D010555:Personality Inventory; D011336:Probability; D011792:Quebec; D012307:Risk Factors; D012933:Social Identification; D014754:Violence / Q000523:psychology* / Q000706:statistics & numerical data