Comparably to our data, in predominately younger aggressive boys with ADHD, the COMT rs4818 GC genotype was over-represented [39], and this genotype was nominally related to the CU traits [39], while in adult males with schizophrenia, COMT rs4818 CC homozygotes had more severe difficulties in abstract thinking compared to G allele carriers [60]. This evidence concerns the gene COMT and attention deficit-hyperactivity disorder.