The relationship between psychosis and offending in New South Wales: A data-linkage study

Currently recruiting: 
The challenge: 

Psychosis is a risk factor for offending, particularly violent offending. The extent to which psychosis contributes to offending is likely to vary due to factors such as treatment practices, legal considerations, and the allocation of resources for mental health services. Further research into the relationship between psychosis and offending is required to better inform policy development with the aim of reducing offending behaviour by people with psychosis.

The project: 

This is the first data-linkage study which examines the relationship between psychosis and offending behaviour using health and judicial administrative data collections in New South Wales. Specifically, the study determines the incidence rates of offending among those with psychosis; population level impact of psychosis on offending behaviour; utilisation of community mental health service prior to incarceration; and the rates and causes of post-release mortality in offenders with and without psychosis.

The method: 

Data from nine heath, judicial and mortality administrative data collections are linked for all people diagnosed with psychosis between July 2001 and December 2012. For each case, two controls without any record of a diagnosis of psychosis are matched by birth year and sex from New South Wales Department of Health records.

The results: 

The linkage has identified all people (444,432) who were diagnosed with psychosis between July 2001 and December 2012 in NSW. Rate of offending among those with psychosis was over four times higher than the control group. Further analysis is underway according to the objectives of the study.

The impact: 

It costs around $6.4 billion annually to run the criminal justice system in Australia to prosecute and punish crimes and their perpetrators. The costs of detaining a medium security adult prisoner is around $85,000 per year (more for maximum security), and over $200,000 for a juvenile offender. Thus, any new knowledge that can inform our understanding of pathways leading to contact with the criminal justice system and provide insights into the role of mental illness in this trajectory will be of great interest to policy makers, not to mention the personal benefit to those embroiled in the criminal justice and the community as a whole. These insights open up the possibility of diverting people away from the criminal justice system and into treatment.

Project contact: 
Professor and Program Head
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