COMT and attention deficit-hyperactivity disorder: There was a direct effect of COMT on social impairment (β = -3.0516; t = -2.8557; p = 0.0045), and of social impairment on ADHD symptom strength (β = 0.0178; t = 3.1175; p = 0.0019), but no effect of COMT on ADHD symptoms (β = -0.0099; t = -0.0748; p = 0.9404) (Figure 2).