Objective: To assess the impact of childhood conduct disorder (CD) and intelligence quotient (IQ) on later substance use in adolescence.
Methods: Neuropsychological and structured diagnostic evaluations were initially administered to 32 children with disruptive behavior disorder when they were 7–11 years of age. They were then re-evaluated on average 6.7 years later using an array of interviews and rating scales with a focus on substance use.
Results: Early CD and IQ scores together accounted for a significant proportion of the variance in later substance use (R2=.248). In addition, there was a significant CD and Verbal IQ interaction (R2=.164) such that high Verbal IQ was linked to increased substance use in adolescents who had childhood CD.
Conclusion: These data indicate that the presence of conduct disorder may interact with high Verbal IQ during childhood in such a way as to predict later adolescent substance use in disruptive behavior disorder populations.