ABSTRACT
Persons with severe mental illness 1 (SMI) (Hodgins et al. 1996), and most particularly those with schizophrenia and schizo-affective disorder, are at increased risk, as compared to the general population, to commit violent crimes. This is a robust finding. It has been reported by several independent research groups working in industrialised (Arseneault et al. 2000; Brennan et al. 2000; Tiihonen et al. 1997; Wallace et al. 2004) and underdeveloped countries (Volavka et al. 1997) with distinct cultures and health, social service and criminal justice systems, who have examined different cohorts and samples using various experimental designs including prospective, longitudinal investigations on birth cohorts (Arseneault et al. 2000; Brennan et al. 2000; Tiihonen et al. 1997) and population cohorts (Wallace et al. 2004), follow-up studies comparing patients and their neighbours (Belfrage 1998), random samples of incarcerated offenders (Fazel and Danesh 2002), and complete cohorts of homicide offenders (Erb et al. 2001). A recent study showed that among people living in the community, the presence of psychotic symptoms in the absence of a psychotic disorder was associated with increased risk of aggressive behaviour (Mojtabai 2006). Much less is known about the prevalence of violent criminality among persons with major affective disorders than among those with schizophrenia. The few existing studies suggest a weak relationship (Arseneault et al. 2000; Brennan et al. 2000).
