The effect of childhood conduct disorder and cognitive functioning on adolescent substance use

To assess the impact of childhood conduct disorder (CD) and intelligence quotient (IQ) on later substance use in adolescence.

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.

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.

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.