 2010 The Royal Australian and New Zealand College of Psychiatrists Olav B. Nielssen, Psychiatrist (Correspondence) University of New South Wales, Sydney; Clinical Research Unit for Anxiety and Depression, Level 4, O’Brien Building, StVincent’ s Hospital, Darlinghust, New South Wales 2010, Australia. Email: olavn@ozemail.com.au Natalia Y. L. Yee, Psychologist Department of Psychological Medicine National University Hospital, Singapore Matthew M. Large, Psychiatrist University of New South Wales, Prince of Wales Hospital, Randwick, New South Wales, Australia Richard I. Kemp School of Psychology, University of New South Wales, Sydney, New South Wales, Australia Received 25 April 2010; accepted 16 November 2010 Severe non-lethal violence during psychotic illness Natalia Y. L. Yee, Matthew M. Large, Richard I. Kemp, Olav B. Nielssen Background: Research about violence in psychosis has mainly considered homicide by people with mental disorder, especially schizophrenia, and violence in groups of psychiatric patients. In this study we examine the characteristics of a sample of offenders with psy- chotic illness who committed severe non-lethal violent offences. Method: A review of court documents from a consecutive series of cases involving violence resulting in signiicant injury concluded in the District Court of New South Wales, Australia, in the years 2006 and 2007. Results; Of 661 people found to have committed a severe violent offence, 74 (11%, 95% conidence interval (CI) 9–14%) had a diagnosed psychotic illness. Of these, 16 (22%, 95% CI 12–31%) had never received treatment with antipsychotic medication and could be regarded as being in the irst episode of psychosis. Offenders with psychosis were typically non-adherent to treatment, had co-morbid substance use and prior criminal convictions. Positive symptoms of psychotic illness such as hallucinations and delusional beliefs were reported to be present at the time of the offence in most of the cases. Seven of 74 (10%) psychotic offenders were found not guilty on the grounds of mental illness. Conclusions: People with psychotic illness are over-represented among those who com- mit violent offences resulting in signiicant injury, conirming the presence of an association between psychosis and severe non-lethal violence. Earlier treatment of irst episode psy- chosis, improving the adherence to treatment of known patients and treatment of co-morbid substance abuse could reduce the incidence of severe violence committed by patients with psychosis. Key words: assault, irst episode, psychosis, schizophrenia, violence. Australian and New Zealand Journal of Psychiatry 2010; Early Online, 1–7 Mental disorder accounts for a small proportion of all crime [1,2]. However, there is a well-established associa- tion between schizophrenia and violence [3–8], espe- cially homicide [9–12]. Two recent meta-analyses of studies from developed countries found that people with a diagnosis of schizophrenia commit 6.5% of homicides, irrespective of the total homicide rate [13] and that the odds ratio (OR) for all forms of violent offending when compared to the general population is 4 for men, 8 for women and 20 for homicide by either sex [14]. The relationship between schizophrenia and violence has been examined in studies that link criminal histories to records of psychiatric treatment [3,6,8,15] and in case Aust NZ J Psychiatry Downloaded from informahealthcare.com by University of Sydney on 12/15/10 For personal use only.