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.