Prisoners convicted of serious violent offences were found to be less aggressive and less likely to reoffend following a mental health intervention which could save money and reduce harm to society, according to new research led by King's College London.
The research, funded by the National Institute for Health and Care Research (NIHR) and published in (PLOS One) provides the first unique high-quality evidence of the cost-effectiveness of Mentalization Based Therapy (MBT) and probation in men convicted of violent crimes, who have antisocial personality disorder (ASPD). The randomised controlled trial ran across UK prisons and probation services and involved more than 300 prisoners. They were split at random into two groups, one getting the mental health intervention alongside probation support, the other getting probation support on its own.
The researchers assessed the outcomes of the trial 24 months after the participants had been allocated to each group. They assessed the economic costs to society, incorporating costs to healthcare and the criminal justice system and the wider impact of offending. They found that the group who had received the mental health intervention and probation were associated with reduced costs and lower aggression which would give potential cost savings of approximately £93 per person compared to the current probation service provision.
Antisocial personality disorder is characterised by a persistent pattern of behaviours including chronic aggression, recklessness, irritability, deceitfulness, irresponsibility, and a marked lack of remorse. Although its prevalence in the general population is relatively low, rates can reach up to 50% among men convicted of violent offences where it is associated with more serious and persistent offending.
ASPD imposes a substantial economic burden on both health and criminal justice services and most importantly contributes to serious harm and enduring consequences for victims, while complicating the management of offenders in both prison and in communities. Despite this, evidence on the cost-effectiveness of pharmacological or psychological interventions remains extremely limited, constraining efforts to provide effective solutions and resources.
Professor Barbara Barrett, Professor of Health Economics at King's College London and lead author says: "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."
The research team carried out the study through structured interviews and a self-reported questionnaire recording use of services providing accommodation, education, employment and training. Clinicians and people with lived experience of prison and probation services helped to develop research questions to ensure they were appropriate and robust.
The average cost of delivering MBT (£826.30 per participant) is comparable to other community-based psychological interventions, and this expenditure was offset by savings elsewhere, particularly in reduced custodial time and lower offence-related costs.
However, due to the complex challenges inherent in following up with this population over two years there was a drop in the rates of data completed for the study at 12 or 24 months. Despite the gaps in data the researchers found that consistent findings across their analysis and concluded that the mental health intervention plus probation service support is a promising cost-effective intervention for this population.
Dr Elizabeth Simes, UCL, second author of the study says: "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."
