The regression model with COMT as predictor, ADHD symptoms as dependent variable, and social impairment as moderator was significant [F = 29.834; p < 0.001; explained variance of ADHD symptoms: R2 = 19.09%; female: 13.55% (p < 0.001); male: 22.32% (p < 0.001)]. This evidence concerns the gene COMT and attention deficit-hyperactivity disorder.