Adult outcomes of attention deficit hyperactivity disorder and conduct disorder: are the risks independent or additive?

METHODS: Data were obtained from a longitudinal study sample of 754 adoptees and categorized based on review of the available adoption agency, medical, and psychiatric records of the biological parents. Categorical data were analyzed using chi2 or Fisher's exact tests, as appropriate. Logistic regression analyses were used to assess the relative contribution of variables.

RESULTS: There was not a statistically significant difference in the frequency or type of self-reported adult disruptive behavior, arrests, jail stays, felony arrests, or frequency of conduct disorder (CD) when inattentiveness, impulsivity, and hyperactivity were analyzed individually. The contributions of attention deficit hyperactivity disorder (ADHD) were independent and no additional increased risk for future illegal behavior was conferred by the combination of the disorders. While the effect of CD on illegal behavior was correlated with substance abuse and dependence, ADHD continued to be a significant contributor after controlling for substance abuse and dependence.

CONCLUSIONS: Data indicated that ADHD and CD are related but different disorders conferring risk for adult illegal behavior or arrest. In this sample, inattention was the most common domain impaired among those with ADHD, followed closely by hyperactivity, with impulsivity reported least often among those endorsing symptoms of ADHD.