Abstract
High rates of offending and violence have been found in patients with co-morbid severe mental illness and substance misuse (dual diagnosis), although research has focused upon inner-city populations. This study compares offending and violence rates in patients with dual diagnosis (DD) and patients with psychosis only, drawing on a more demographically representative population. Forty patients with severe mental disorders were interviewed in a geographically defined catchment area in Croydon, Surrey. Cases of alcohol or drug misuse were identified, and measures of lifetime history of offending (including violence) and recent violence were obtained. DD patients were more likely to report a lifetime history of both offending and violence than patients with psychosis only (although gender may play a greater role than substance misuse). Few instances of recent violence were found, and no between-group differences were detected. The medical caserecords of DD patients were significantly more likely to contain a lifetime history of non-substance misuse-related offending, but not violence. However, the extent to which substance misuse contributes to violence and offending independently of contextual variables requires further investigation.