Is ADHD a risk factor independent of conduct disorder for illicit substance use? A meta-analysis and metaregression investigation.

OBJECTIVE

To investigate meta-analytically if the association between ADHD and illicit substance use (ISU) is maintained when controlling for conduct disorder/oppositional-defiant disorder (CD/ODD).

METHOD: A systematic literature review was conducted through Medline from 1980 to 2008. Data extracted and selections made by one author were reviewed by another.

RESULTS

Fifteen articles presented odds ratios (ORs) for the development of ISU in individuals with ADHD controlling for CD/ODD. In total, the study covered results for more than 1,000 individuals. The combined OR for studies that included in their analysis exclusively ISU was 1.35 (0.90-2.03), p = .15, heterogeneity = 55%. Lack of control for socioeconomic status was related with a weaker association between ADHD and ISU.

CONCLUSION

The existing data do not indicate that ADHD increases the risk of ISU beyond the effects of CD/ODD. However, the combination of all existing data is limited in power to detect a small increase in chance.