It is often assumed that those diagnosed with mental illness are of greater danger to the public-at-large. The spate of mass shootings in the United States has brought about increased debate on the issue, much of which focuses on the relationship between crime and mental illness, and is often based on incorrect information.
On the contrary, for a vast majority of psychiatric diagnoses, there is no predictive association with incarceration, according to a recent study published in the journal Psychological Medicine. "We do know that there are higher levels of mental illness among prisoners, but this may be a result of incarceration and prison conditions. Our findings shows that they are not the predictor of incarceration," says Prof. Sophie Walsh, of the Department of Criminology at Bar-Ilan University, one of the researchers involved in the study.
The study examined the relationship between psychiatric diagnoses and future incarceration. The research was based on data of psychiatric interviews performed in a representative sample of the adult population aged 25-34 in the 1980s in Israel. Two distinguished members of this well-known cohort study, Prof. Bruce Dohrenwend, of Columbia University, and Prof. Itzhak Levav, of the University of Haifa, were collaborators on the current study, as well as Prof. Gilad Gal, from the Tel-Aviv Yafo Academic College, who led the analysis of the data. Researchers from Tel Aviv University and Sheba Medical Center were also involved in the study.
Data on the participants of the cohort study were merged with 30 years of follow-up data from the Israel Prison Service. This unique data set enabled the researchers to see who from the original cohort study of 5,000 was later incarcerated in what may be the first prospective study of its kind.
Study findings showed that diagnoses of substance use and antisocial personality were predictors of future incarceration but that other psychiatric diagnoses (i.e., schizophrenia, affective disorders, anxiety disorders, as well as some other psychiatric disorders) were not independent predictors of incarceration. In addition, the association between the number and maximal length of incarceration for participants with affective disorders, anxiety disorders, substance abuse, antisocial personality, and 'other psychiatric diagnoses' were examined, and compared to incarcerated participants with no diagnosed disorder. Substance abuse was found as a significant risk factor for repeat incarcerations, antisocial personality showed marginal significance, while affective disorders, anxiety disorders, and 'other psychiatric disorders' showed no association. Longer periods of incarceration were associated with substance abuse and, to some extent, with antisocial personality. No significant differences were found for affective disorders, anxiety disorders, and 'other psychiatric disorders'.
The findings also challenge the myth of ethnic origin and incarceration: among Ashkenazi and Sephardic participants, ethnic origin was not a predictor of incarceration once levels of education were controlled for.
"This study rejects several common stigmas, such as ethnic origin and psychiatric diagnoses, as a predictor of incarceration," says Walsh. Hopefully these findings will encourage treatment for substance abuse and antisocial personalities and increase awareness of mental illness in prisons.