The impact of personality disorders, substance use and other mental illness on re-offending

Abstract

It is frequently observed in the literature that mental illness is associated with criminal offending; however, co-morbidity between personality disorders, substance use disorders and other mental illnesses complicates our understanding of this relationship. The aim of this study is to determine the impact of co-morbid substance use disorder, personality disorder and mental illness on the rate of re-offending. Data on 12-month psychiatric morbidity for N = 1264 prisoners who took part in the 2001 Mental Health Survey in NSW, Australia was linked to five years of re-offending data. Risk of re-offending related to psychiatric disorders was assessed using Cox regression. Controlling for sex, indigenous status, age, prior court appearances, sampling frame and psychiatric disorders, participants with a personality disorder had a 26% increase in hazard of re-offending, and those with a substance use disorder a 33% increase in hazard of re-offending. Anxiety disorders, mood disorders and psychotic symptoms did not contribute to re-offending rates, but were highly comorbid with the conditions that were associated with increased re-offending. The findings suggest that the treatment of mentally ill offenders must not simply focus on the treatment of symptoms of mental illness, but should encompass treatments and interventions to target underlying personality and substance use disorders if any reduction in re-offending is to occur.

Keywords:

• substance use disorders
• personality disorder
• recidivism
• offenders
• risk assessment

Acknowledgements

The authors wish to acknowledge Nadine Smith, Lily Tromboli and Craig Jones of the NSW Bureau of Crime Statistics and Research for linking the survey data to the offending data. They would also like to acknowledge Professor Tony Butler for collecting the 2001 Mental Health Survey data.