COMT and attention deficit-hyperactivity disorder: In line with this finding, the COMT rs4680 A allele has been previously associated with physical violence against others and angry behavior in patients with schizophrenia [57,58], physical and relational violence in young adults [38], higher hyperactivity, impulsivity, and inattentive symptoms in children with ADHD [48], higher aggressive and depressive symptoms and a history of suicide attempts in male subjects with alcoholism [59], and with higher scores on difficulties in abstract thinking in patients with schizophrenia [60] compared to GG homozygotes.