However, we found an indirect effect of COMT on ADHD moderated by social impairment (β = -0.0544; Z = -2.0492; p = 0.0404), and significant effects of the two covariates (sex: β = 0.7060; t = 3.9237; p = 0.0001; conduct problems: β = 0.5757; t = 8.9919; p < 0.0001). Here, COMT is linked to attention deficit-hyperactivity disorder.