The severity of the PANSS positive, negative, and general psychopathology symptoms of schizophrenia, and cognitive decline evaluated with PANSS cognitive subscale, that includes items P2 (conceptual disorganization), N5 (abstract thinking), G10 (disorientation), and G11 (attention problems), as well as scores on particular items of PANSS scale, were evaluated in regard to COMT rs4818 and rs4680 polymorphisms and COMT rs4818–rs4680 haplotype in male and female subjects separately. This evidence concerns the gene COMT and Mental deterioration.