Violence in male patients with schizophrenia: Risk markers in a South African population

Objective: We investigate the role of functional variants in the catecholamine-O-methyl transferase gene (COMT) and the monoamine oxidase-A gene (MOA-A), as well as previously identified non-genetic risk factors in the manifestation of violent behaviour in South African male schizophrenia patients. Method: A cohort of 70 acutely relapsed male schizophrenia patients was stratified into violent and non-violent subsets, based on the presence or absence of previous or current violent behaviour. Standardized violence rating scales were also applied and the COMT/NlaIII and MAO-A promoter region variable number of tandem repeats (VNTR) polymorphisms were genotyped. Results: A multiple logistic regression model based on the clinical, genetic and socio-demographic variables indicated that delusions of control (OR = 3.7, 95% CI = 1.21-11.61) and the combined use of cannabis and alcohol (OR = 6.89, 95% CI = 1.28-37.05) were two significant predictors of violent behaviour in this schizophrenia population. No association was found between the tested polymorphisms and violent behaviour. Conclusions: Although the sample size may have limited power to exclude a minor role for these specific gene variants, such a small contribution would have limited clinical relevance given the strong significance of the non-genetic markers. These findings suggest that currently proactive management of violent behaviour in this schizophrenia population should continue to be based on clinical predictors of violence.