Does conduct disorder mediate the development of substance use disorders in adolescents with bipolar disorder? A case-control family study

Background: Recent work has highlighted important relationships among conduct disorder (CD), substance use disorders (SUD), and bipolar disorder in youth. However, because bipolar disorder and CD are frequently comorbid in the young, the impact of CD in mediating SUD in bipolar disorder youth remains unclear. Method: 105 adolescents with DSM-IV bipolar disorder (mean ± SD age = 13.6 ± 2.50 years) and 98 controls (mean ± SD age = 13.7 ± 2.10 years) were comprehensively assessed with a structured psychiatric diagnostic interview for psychopathology and SUD. The study was conducted from January 2000 through December 2004. Results: Among bipolar disorder youth, those with CD were more likely to report cigarette smoking and/or SUD than youth without CD. However, CD preceding SUD or cigarette smoking did not significantly increase the subsequent risk of SUD or cigarette smoking. Adolescents with bipolar disorder and CD were significantly more likely to manifest a combined alcohol plus drug use disorder compared to subjects with bipolar disorder without CD (χ² = 11.99, p < .001). Conclusions: While bipolar disorder is a risk factor for SUD and cigarette smoking in a sample of adolescents, comorbidity with preexisting CD does not increase the risk for SUD. Further follow-up of this sample through the full risk of SUD into adulthood is necessary to confirm these findings.