A major new study published in The Lancet Psychiatry has shown that prisoners who suffer from a range of psychiatric disorders are more likely to commit violent crimes once they are released from jail.

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Research suggests a link between psychiatric disorders and violent reoffending.

According to the report, violence is decreasing in many countries, but reoffending – especially in mid- and high-income countries – remains high, with more than 33% of prisoners in the US and UK being reconvicted within 2 years and more than 50% within 5 years. In the US, approximately 70% of convictions are of repeat offenders.

The research followed almost 48,000 prisoners in Sweden, both men and women, who were convicted after January 1st, 2001 and released before December 31st, 2009. It found that up to 20% of violent reoffending by males and 40% by females is most likely due to psychiatric disorders.

The findings have implications for the provision of support for prisoners both before and after release, in terms of helping to rehabilitate individuals and to ensure public safety.

Psychiatric disorders commonly affecting offenders include schizophrenia, bipolar disorder, attention deficiency hyperactive disorder (ADHD), a range of personality disorders and substance abuse. In contrast with previous research findings, substance abuse alone does not appear to be the main cause of violent crime, but in conjunction with other disorders, it significantly increases the likelihood of violent reoffending.

Moreover, the more disorders an individual has, the higher the likelihood of a violent crime being committed. According to the report, 15% of all prisoners in the US are estimated to have a severe mental illness, and there are 10 times more people with mental illness in jails than there are in psychiatric hospitals.

The team, composed of researchers from Sweden and the UK, used Swedish population registries to make the comparisons. In Sweden, all residents have a unique personal identifier, which enables linkage across different registries, such as the National Crime Register and the National Patient Register, making it possible to track individual progress more accurately.

Fast facts about mental health
  • Around 1 in 4 adults in the US experience a diagnosable mental disorder in any given year
  • Mental disorders are the leading cause of disability in the US for individuals aged 15-44
  • Around 45% of people with a mental disorder meet the criteria for at least two other mental disorders.

Learn more about mental health

It was found that 42% of male prisoners and 60% of females suffered from some kind of psychiatric disorder before release; and that 25% of all males and 11% of all females went on to commit violent crimes in the 3.2 years following release. This was regardless of marital, social and economic status.

In addition, for those with a psychiatric disorder, the average amount of time taken to reoffend was 2.4 months shorter for men and 4.8 months shorter for women, compared with those who did not have a disorder.

Overall, a higher proportion of female prisoners had a psychiatric disorder, compared with men, but females were also proportionally less likely to commit a violent crime.

In the light of these findings, lead researcher Seena Fazel, professor of forensic psychiatry at the University of Oxford in the UK, calls for “improved detection, treatment and management of prisoners with mental health disorders, and linkage of these prisoners to community-based mental care services on release,” especially since these disorders are “prevalent and mostly treatable.”

In a linked comment, Prof. Louis Appleby, national director for health and criminal justice and professor of psychiatry at the University of Manchester in the UK, calls for social factors such as poor housing and unemployment to be tackled first.

He has also voiced concern that such information will undo work that has been achieved in improving public attitudes toward mental illness and reducing the stigma attached to it; according to Prof. Appleby, the research is being blamed for “stoking public fear and discrimination.”

With more than 10 million people in prison worldwide and prison and health services under financial strain in many countries, the cost of providing this support will be a drawback. However, with the cost of reoffending in England and Wales alone estimated to be some $14.5-19.5 billion a year, it can well be argued that the extra support is a worthwhile investment, not only in human terms, but also financially.

Earlier this year, Medical News Today reported on a study that found former prisoners are at high risk of death from drug and alcohol abuse.