Background: The risk of psychotic symptoms in methamphetamine dependent individuals is eleven times higher as compared to the general population. Dopamine, which is one of the key neurotransmitters in etiopathogenesis of psychosis, is metabolised by catechol-O-methyltransferase (COMT). The COMT gene Val158Met polymorphism changes activity of the COMT enzyme up to fourfold and thus influences the dopamine activity in the brain. The aim of the study was to ascertain whether subjects dependent on methamphetamine with psychotic symptoms significantly differ from methamphetamine dependent individuals without psychosis in the Val158Met COMT genotype or allele frequency. Methods: Methamphetamine dependent inpatients who had signed the informed consent were enrolled into the study.We assessed psychotic symptoms according to the ICD-10 classification of mental disorders (Dgs F15.50 to F15.53). The COMT genotype was detected by the PCR (polymerase chain reaction). Results: Eighty-three patients (25 women) at the age of 18–38 years (median 22 years) dependent on methamphetamine entered the study. We found psychotic symptoms in 18 subjects (8 women). No significant association between psychosis in methamphetamine dependence and the Val158Met COMT genotype or allele frequency was proved (P = N.S.; Fisher´s Exact Test). Conclusions: Our results may have been influenced by the joint assessment of males and females in one sample, hidden ethnic stratification or interaction of the Val158Met COMT gene polymorphism with other genes and environmental factors.

        Key words: methamphetamine dependence, psychosis, dopamine, catechol-O-methyltransferase; COMT gene Val158Met polymorphism.