Ex-prisoners with common mental health problems, such as bipolar disorder, and who misuse drugs and alcohol are more likely to commit violent offences after their release than other former prisoners, according to research. The study, published in the Lancet Psychiatry journal, suggests that diagnosed psychiatric disorders are responsible for 20% of violent offences committed by male ex-prisoners and 40% of those committed by female former inmates.

https://www.theguardian.com/society/2015/sep/03/ex-prisoners-mental-health-problems-more-likely-reoffend-study