The most common cause of disability and death in younger adults is traumatic brain injury, most often resulting from a fall, assault or road traffic accident.

It can be predicted that persisting effects of brain injury which include impulsiveness, aggression, intolerance, egocentricity, poor judgement and lack of concern for others might increase the risk of criminal behaviour and arguably other effects that impair memory, concentration and problem solving make being caught more likely.

A review paper by Williams and colleagues, published in the Lancet today summarises research evidence to date.

Traumatic brain injury is not only commonly reported in prisoners, but is a risk factor for violent crime, infractions and poorer treatment gains in prison and reconviction.

Life experiences of adversity including severe economic disadvantage, parental loss, abuse, and neglect are more common, particularly in younger adults and this raises the question of whether TBI is simply associated with a background of this kind, or is a driver for criminal behaviour. Recently there have been studies linking health data to criminal convictions which begin to suggest that there is a causal link.

A small number of studies have shown that the risk of crime, including crimes of violence remains higher in people with TBI than in their siblings who have been exposed to a similar background of adversity, but have not suffered a TBI. The costs are potentially very high if considering the impact on victims and their families, lasting antisocial lifestyle in the perpetrators. In addition, the Centre for Mental Health calculates the financial cost to be several hundred thousand pounds higher over the lifetime if a criminal has had a TBI.

In Scotland work is in progress to develop a system for identification of people in the criminal justice system not just who have had a TBI, but whether there is persisting disability that merits intervention. This work was instigated by the Scottish Government via the NHS National Prisoner Health Network who reported in July 2016 and is being carried out in partnership with the University of Glasgow.

The report outlines a pathway for a service for people with TBI and spans police custody, prison and return to the community with emphasis on triage to services that might range from lighter touch education programmes to more intensive specialist work designed to reduce the likelihood of reoffending and also the risk of further, repeat TBI which is high in this group.

Tom McMillan PhD FBPSs

Professor of Clinical Neuropsychology

Institute of Health and Welllbeing

University of Glasgow