To Örebro University

Objective: Head injury during development has been associated with behavioral changes such as impulsivity and antisocial behavior. This study investigates the extent to which behavioral changes associated with childhood head injury are sustained through adolescence and emerging adulthood.

Method: Survey data was collected at 5 waves spanning 12 years (ages 9-20) from the University of Southern California Risk Factors for Antisocial Behavior twin study. Impulsivity was measured by errors of commission in a Go/NoGo behavioral task, and aggression was measured through youth self-report using the Reactive-Proactive Aggression Questionnaire. Head injury was assessed retrospectively using caregiver questionnaires at twin ages 14-15 years and self-reported at ages 19-20 years.

Results: Participants with a head injury in early childhood showed significant delay in the normative developmental decline of impulsivity relative to the noninjured by mid-adolescence (ages 14-15.) Moreover, earlier age at injury was related to a slower decrease in impulsivity and greater increase in reactive aggression scores. Finally, among discordant monozygotic twin pairs, the twin with a head injury experienced significantly less decline in impulsivity by ages 19-20 than the noninjured co-twin.

Conclusions: These findings indicate early childhood head injury may play a significant role in blunting the decline in impulsivity across development, exposing an additional risk factor for antisocial behavior.