Risk factors for criminal offending among men with schizophrenia

Abstract

Background: There is consistent evidence for an association between schizophrenia and criminal offending. With better knowledge of the relation between schizophrenia and criminal offending, better and more cost-effective methods for prevention of criminal offending could be expected and public fear of mentally ill persons being reduced. The overall aim of the present study was to advance knowledge regarding risk factors or potential risk factors for criminal offending among males with schizophrenia. Specifically, one aim was to investigate the associations between low verbal intelligence and early-onset, persistent offending among males with schizophrenia. Another aim was to validate alcohol use typologies among males with schizophrenia.

Methods: The study was based on data provided from the Comparative Study of the Prevention of Crime by Mentally Ill Persons, an international, multi-site follow-up study on patients from forensic psychiatry (n = 186) and patients from general psychiatry (n = 122), led by Professor Sheilagh Hodgins. All participants underwent extensive assessment at discharge. The instruments used were SCID, WAIS-R, PCL-R, PANSS, and NEO-PI-R. Information on background, criminality and follow-up data was collected from all available sources, including the participant and a family member, staff, and records. In Paper I, base-line data from discharge was used along with historical data. The participants of Paper I were men with schizophrenia spectrum disorders (n = 219). Data were analysed by uni-variate methods and by standard multiple regressions. In Paper II, base-line data, historical data and prospective measures from the follow-up were used. The participants of Paper II were men with schizophrenia spectrum disorders and alcohol use disorders (n = 139). Data were analysed by uni-variate methods and by k-means cluster analyses.

Results: Low verbal IQ did not increase the risk for criminal offending among men with schizophrenia spectrum disorders, but among those who did offend it was associated with a younger age at first conviction for a non-violent crime (Paper I). Widely used uni-dimensional and multi-dimensional typologies of alcohol use disorders, developed in settings with non-mentally disordered individuals, were replicated and showed at least some degree of concurrent validity in a sample of men with schizophrenia spectrum disorders and alcohol use disorders although the predictive validity was weak (Paper II).

Conclusions: The results of the study suggest that individuals with schizophrenia constitute a heterogeneous population. Treatment planning must be kept at an individual basis and set out from qualified and thorough assessments of individual needs. When assessing risk for criminal offending, the conditional nature of risk factors must be considered. Finally, programmes for crime prevention (risk management) should be individually designed as well, to ensure that all interventions include the necessary features and are kept at a proper level.