Cannabis use and violent behaviour: a psychiatric patients cohort study in Southern Italy

An ample volume of research evidence supports the conclusion that drug use/abuse is correlated with violent behaviour. Some studies have shown that co-morbidity also appears to be predictive of violent behaviour. The research evidence indicates gender differences, while socio-economic and familial factors play a role, too. Method. We conducted a retrospective study of the clinical files of four public psychiatric outpatient facilities during five years. The objectives of the research were to identify and analyze relationships between: a) cannabis use/abuse and violent behaviour and b) cannabis use/abuse, psychopathology, and violent behaviour. The study sample consisted of 1,582 subjects. The data, gathered in a dedicated database, were processed by applying univariate and multivariate analysis models. Results. Subjects who used/abused cannabis showed a high prevalence of violent behaviour. Regardless of the type of psychiatric disorder, the use of cannabis appears to be an evident risk factor. Significant correlations also emerged between cannabis use/abuse and the type of violent behaviour, especially self-inflicted injury. Evidence also emerged that other factors are implicated. This is consistent with the current literature proposing multi-causal explanations of violent behaviour