Delinquent behavior and emerging substance use in the MTA at 36 months: prevalence, course, and treatment effects

OBJECTIVE: To compare delinquent behavior and early substance use between the children in the Multimodal Treatment Study of Children With ADHD (MTA; N = 487) and those in a local normative comparison group (n = 272) at 24 and 36 months postrandomization and to test whether these outcomes were predicted by the randomly assigned treatments and subsequent self-selected prescribed medications. METHOD: Most MTA children were 11 to 13 years old by 36 months. Delinquency seriousness was coded ordinally from multiple measures/reporters; child-reported substance use was binary. RESULTS: Relative to local normative comparison group, MTA children had significantly higher rates of delinquency (e.g., 27.1% vs. 7.4% at 36 months; p = .000) and substance use (e.g., 17.4% vs. 7.8% at 36 months; p = .001). Children randomized to intensive behavior therapy reported less 24-month substance use than other MTA children (p = .02). Random effects ordinal growth models revealed no other effects of initial treatment assignment on delinquency seriousness or substance use. By 24 and 36 months, more days of prescribed medication were associated with more serious delinquency but not substance use. CONCLUSIONS: Cause-and-effect relationships between medication treatment and delinquency are unclear; the absence of associations between medication treatment and substance use needs to be re-evaluated at older ages. Findings underscore the need for continuous monitoring of these outcomes as children with attention-deficit/hyperactivity disorder enter adolescence.