Objective: In a recent study, Thapar and colleagues reported that COMT "gene variant and birth weight predict early-onset antisocial behavior in children" with attention-deficit/hyperactivity disorder. We have attempted to replicate these findings in a group of ADHD children using a similar research design.
Method: Children (n=191) between 6 and 12 years of age who were diagnosed with ADHD were included in the study. Conduct disorder was diagnosed according to DSM-IV criteria based on clinical evaluation and a structured interview (Diagnostic Interview Schedule for Children-IV). The mother's report on the child's birth weight was used in the analysis. Logistic regression analysis, with genotype and birth weight as independent variables and DSM-IV conduct disorder as the dependent variable, was conducted.
Results: No significant main effects of genotype and birth weight or interaction effects on conduct disorder were observed.
Conclusion: In this sample of children diagnosed with ADHD, we find no association between the COMT ValMet gene variant, birth weight, and conduct disorder. Further investigations are required before using birth weight and COMT genotype as predictors of conduct disorder in children with attention-deficit/hyperactivity disorder, especially given the societal and legal ramifications of conduct disorder.