Investigating the clinical correlates of violent behaviour in schizophrenia

Background: There is an association between schizophrenia and violence, although the specific drivers for this link remain unclear. This study aimed to explore the relationships between childhood adversity, conduct disorder, substance misuse and violence among men with schizophrenia. It has been suggested that there may be different pathways to violence in schizophrenia, one primarily linked with pre-morbid conduct disorder, so patients were specifically grouped on the basis of pre-morbid conduct disorder. Methods: Ninety-three male participants were recruited for the study, fifty-four with schizophrenia and thirty-nine healthy controls. Participants underwent a range of clinical assessments, including symptoms of conduct disorder, exposure to childhood adversities and history of substance use disorders. Adult propensity to violence was measured using the Gunn Robertson Violence Scale. Those participants who consented also had a structural magnetic resonance imaging scan. Results: The Gunn Robertson Violence Scale has good validity in this population. Conduct disorder was associated with an increased propensity to violence. Exposure to domestic violence during childhood and the cumulative number of childhood adversities were both associated with adult propensity to violence and attenuation of the association with cumulative adversities suggested that conduct disorder may be a mediator of the relationship. Patients with pre-morbid conduct disorder began using alcohol and cannabis earlier and more frequently, and had higher rates of lifetime substance use disorders which were associated with an increased propensity to violence. An increase in grey matter volume in the caudate was correlated with an increased lifetime propensity to violence. Conclusions: Conduct disorder, substance use disorders, childhood adversity, schizophrenia and violence are all associated with each other. Hence there is a complex interplay of factors, with their origin in childhood, which increase the risk of violent behaviour in schizophrenia.