Prisoners convicted of serious violent offences were found to be less aggressive and less likely to reoffend following a mental health intervention, according to research led by King's College London on Jul. 22. The study was funded by the National Institute for Health and Care Research and published in PLOS One.
The randomized controlled trial involved more than 300 prisoners across UK prisons and probation services. Participants were randomly assigned either a mental health intervention called Mentalization Based Therapy (MBT) alongside probation support or probation support alone. Researchers assessed outcomes 24 months after allocation, examining economic costs to society, including healthcare, criminal justice system expenses, and the broader impact of offending.
Findings showed that those who received MBT with probation had reduced costs and lower aggression levels compared to those receiving only probation support. The potential cost savings were estimated at approximately £93 per person compared to current service provision. The average cost of delivering MBT was £826.30 per participant, which researchers said is comparable to other community-based psychological interventions, with expenditures offset by reductions in custodial time and offence-related costs.
Antisocial personality disorder (ASPD), characterized by chronic aggression, recklessness, irritability, deceitfulness, irresponsibility, and lack of remorse, is prevalent among men convicted of violent offences—up to 50%—and imposes significant economic burdens on health and criminal justice systems while complicating offender management.
Professor Barbara Barrett of King's College London said, "The importance of evidence-based solutions is especially important given the high rates of reoffending among individuals with ASPD. This intervention provides significant potential for long-term cost savings across health and criminal justice systems." Dr. Elizabeth Simes from University College London added, "This study is the first multi-site randomised controlled trial conducted within the National Probation Service in England and Wales and is strengthened by the involvement of a hybrid research team comprising researchers both with and without lived experience. The study demonstrates that a psychological intervention can improve outcomes and is cost-effective for a population that has traditionally been considered difficult to treat."
