Psychosis and offending in British Columbia: characteristics of a secure hospital population

Abstract

INTRODUCTION: There is an increased likelihood of violence in the mentally ill although the risk is small. AIMS: The study aimed to ascertain the features in a secure hospital population that linked offending and mental illness. METHOD: A survey of patients in the high security hospital serving the province of British Columbia in Canada was carried out. Information on 175 mentally disordered offenders was extracted and included demographic data and specific characteristics of their offences, diagnoses and psychotic symptoms. RESULTS: The most prevalent offences were crimes of violence, but 39% of patients were not primarily violent offenders. Almost two-thirds (61%) had two or more diagnoses. A large majority of the patients were psychotic, schizophrenia being the most common diagnosis. There was a highly significant association between psychosis and violence, but the strength of the association was not increased by the presence of imperative hallucinations or delusions. The sample comprised various ethnic groups, one of which, Native Americans, was over-represented. However, no association was found between violent offending and ethnicity, or age or years of illness. DISCUSSION: The study replicates previous findings of the link between violent offending and psychosis, but not a specific link between violent offending and psychotic drive. A surprising finding was a lack of association between violent offences and substance misuse.