The relationship between catechol-O-methyltransferase gene Val158Met (COMT) polymorphism and premorbid cannabis use in Turkish male patients with schizophrenia

One of the risk factors for increasing psychotic disorders is the use of cannabis. It has been shown that the inactivation of dopamine and other catecholamines causes a common polymorphism generating substantial variations in COMT enzyme activity. We aimed to understand the role of cannabis in the etiology of schizophrenia with and without pre-morbid usage. The study group consisted of 80 male patients and genotyping of COMT enzyme Val158Met gene polymorphisms were detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). It was found that the Val/Val genotype is significantly higher in patients with premorbid cannabis use (88.9%) compared to patients without pre-morbid cannabis use (68.4%). Also, the mean total positive and negative syndrome scale (PANSS) score seen in the Val/Val genotype group is significantly higher than the scores of the patients with the Met allele. The findings from this study confirm the association between COMT Val158 Met polymorphism and pre-morbid cannabis use in causing schizophrenia.