The relation between childhood antisocial behavior and the dopamine transporter gene (DAT1): Mediation via hyperactivity-impulsivity

Understanding the etiology and development of antisocial behavior is an important, albeit controversial, goal of psychiatric genetic research. Behavior genetic studies have found substantial heritability for childhood and adolescent antisocial behavior, as well as for attention deficit hyperactivity disorder (ADHD). Given the considerable covariation and overlap between ADHD and disorders representing childhood antisocial behavior (e.g., oppositional defiant disorder [ODD], conduct disorder [CD]), it is reasonable to hypothesize that these disorders share common causes. A number of previous studies have found association and linkage between the dopamine transporter gene (DAT1) and ADHD in children. In this study, we examine the etiological role of DAT1 in childhood antisocial behavior. We sampled DNA and symptoms of ADHD, ODD, and CD from clinic-referred children, their parents, and their siblings in 123 families. We examined linkage disequilibrium between DAT1 and symptoms of these disorders using a logistic regression extension of the Transmission Disequilibrium Test (TDT) designed to accommodate continuous traits. We found evidence suggesting association and linkage of DAT1 with increasing levels of ODD symp-toms (t = 1.94, P = .025), CD symptoms (t = 1.67, P = .047), and the hyperactivity-impulsivity symptoms of ADHD (t = 2.37, P = .009). After controlling for level of hyperactivity-impulsivity symptoms, the relation of DAT1 with both ODD and CD symptoms was nonsignificant (t = 0.20, P = .421 and t = 0.44, P = .329, respectively). These findings suggest that the relation of DAT1 with childhood antisocial behavior appears to be totally mediated by hyperactivity-impulsivity.