COMT and schizophrenia: In male patients with schizophrenia, lower N5 “Difficulties in abstract thinking” scores in COMT rs4680 GG carriers than in A carriers, and overrepresentation of COMT rs4818 G carriers compared to CC polymorphism in participants with less severe N5 scores, suggest an association between the presence higher COMT activity alleles and better preservation of abstract thinking.