Ex-prisoners with common psychiatric disorders such as bipolar disorder (manic-depressive disorder) and alcohol and drug abuse are substantially more likely to commit a violent crime after release than other prisoners, according to new research published in The Lancet Psychiatry journal. The study of almost 48000 ex-prisoners suggests that diagnosed psychiatric disorders are potentially responsible for up to a fifth of violent reoffending by former male prisoners and two-fifths by female ex-prisoners.
"One in seven prisoners have a psychotic illness or major depression and around one in five enter prison with clinically significant substance abuse disorders. As these disorders are common and mostly treatable, better screening and mental health services before and after release are essential to prevent future violence and improve both public health and safety,"  says Seena Fazel, lead author and Professor of Forensic Psychiatry at the University of Oxford in the UK.
In this study, a team of researchers from the UK and Sweden used national registries to study common psychiatric disorders  and any violent convictions (eg, assault, robbery, arson, sexual offenses) in all prisoners released in Sweden between January 1, 2000 and December 31, 2009. The rate of violent reoffending was also compared with sibling prisoners with and without a psychiatric disorder to isolate the impact of the illnesses from other factors that might increase the risk of offending. The researchers then estimated the proportion of violent reoffending that could be attributed to psychiatric disorders (the population attributable fractions; PAF).
Overall, 42% of male prisoners were diagnosed with at least one psychiatric disorder before release and 25% were convicted of violent crimes in the 3.2 years of average follow-up in the released individuals. Around 60% of female prisoners had a psychiatric disorder and 11% were convicted of violent crimes following release.
Male prisoners with any psychiatric disorder were over a half (63%) more likely to commit a violent offence after release than other prisoners, whilst female prisoners diagnosed with a psychiatric disorder were twice as likely be violent following release. These differences remained even after accounting for the influence of age, martial status, employment, education, immigrant background, and criminological and, in the men, familial (genetic and environmental) factors.
All psychiatric diagnoses were associated with an increased rate of violent reoffending. However, the researchers found similar, but higher rates of violent reoffending for prisoners with a history of alcohol and drug abuse, personality disorder, attention deficit hyperactivity disorder (ADHD), other developmental or childhood disorder, schizophrenia, and bipolar disorder (see table 3). The risk of violent reoffending increased in a stepwise way according to the number of psychiatric disorders (see figure 3), highlighting the importance of treating co-occurring conditions.
Interestingly, the time to committing a violent offence after release was much shorter for prisoners with a psychiatric disorder: 2.4 months shorter for men and 4.8 months shorter for women (see figure 2).
The authors caution that more data are needed before diagnosed psychiatric disorders can be causally linked with violent reoffending. According to Professor Fazel, "Because the number of prisoners with psychiatric disorders is large, our findings suggest that better mental health care in prison and stronger links with community health services could improve both prisoners' quality of life and go a long way toward counteracting the cycle of violent reoffending. In the USA, for example, former prisoners account for up to a fifth of all arrests, so better treatment could lead to substantial reductions in the more than 1 million violent crimes committed every year." He adds, "It underscores the importance of treating alcohol and drug misuse actively and with evidence-based therapies." 
The authors conclude by calling for national violence prevention strategies to include prison health in their targets, strategies, and surveillance.
Writing in a linked Comment, Professor Louis Appleby, National Director for Health and Criminal Justice and Professor of Psychiatry at the University of Manchester, UK, and colleagues question whether treatment of mental illness will be effective if poor housing, unemployment, and substance misuse - that are also common among ex-prisoners - are not tackled. They write, "Governments and some justice agencies might be tempted by the simple message that the answers to issues in the criminal justice system lie with mental health services. Meanwhile, the claim that mental illness is a direct cause of violence will make uncomfortable reading in mental health. The implication of this study lies between the two: treatment of psychiatric disorders in prisons and on release is crucial, but will not be enough to bring about a major reduction in violent crime. Comprehensive packages of treatment and social support are needed that hold a therapeutic mirror to the complexity and adversity of offenders' lives."
NOTES TO EDITIORS:
This study was funded by Wellcome Trust, Swedish Research Council, and Swedish Research Council for Health, Working Life and Welfare.
 Quotes direct from author and cannot be found in text of Article.
 Common psychiatric disorders included alcohol and drug misuse or dependence, attention deficit hyperactivity disorder (ADHD), personality disorder, schizophrenia, bipolar disorder, depression, and anxiety disorder.