Researchers at the University of Exeter also found TBI was associated with a greater number of convictions and, when there were three or more TBIs, greater violence in offending.

The research, published online on 10 November in the journal Neuropsychological Rehabilitation, suggests brain injury must be taken seriously in the assessment and management of offenders.

Professor Huw Williams, from the University of Exeter's School of Psychology and lead author of the research, said: "This study shows that TBI is relatively common in offender groups and that it may be associated with reoffending. However, we cannot know whether brain injury per se increases likelihood of offending.

"There may well be underlying risk factors for TBI and offending behaviour. These could include deprivation, lack of life opportunities, low concern for self-care, and even being a person who 'takes risks'. A TBI may be a 'marker' for these other factors."

In the study, young male offenders aged 11 to 19 years were asked to complete self-reports on head injury, crime history, mental health and drug use -- with 197 participants (94% of those asked) taking part.

Traumatic Brain Injury -- an incident involving a blow to the head with a Loss of Consciousness (LOC) -- was reported by 46% of the sample. This is higher than estimates for TBI in society as a whole of between 5% and 30% dependent on age group.

The main cause of injury in the young offenders was violence. In non-offending younger people, injury typically occurs in falls or in sports.

In the study, repeat injury was common -- with a third reporting being "knocked out" more than once. Three or more TBIs were associated with greater violence in offences. Those with self-reported TBI were also at risk of greater mental health problems and of misuse of cannabis.

The research adds to another study published this year by Exeter researchers. Looking at adult offenders in prison, the previous work also found much higher rates of TBI than expected in society as a whole, with 60% claiming to have suffered a concussion. Those who said they had suffered a TBI were, on average, five years younger when they were first in prison compared to non-injured -- 16-years-old compared to 21. They also reported higher rates of repeat offending.

Professor Williams said it is already widely known that TBIs, particularly when there is longer LOC, can lead to problems in attention, memory, planning and problems in behaviour, for example, in anger management and impulse control. This research suggests it should be a key consideration in enabling these young offenders to change their behaviour.

"Taking account of brain injury could help reduce repeat offending in those affected," he said. "Screening for TBI could be included in the health assessments of offenders to identify those who need more detailed assessment for providing appropriate management. Importantly, adolescence could be a critical window of opportunity for diverting young offenders at risk of injury and of further offending into non-offending lifestyles."

The research was carried out in partnership with the United Kingdom Acquired Brain Injury Forum (UKABIF) and funded by the Big Lottery and the Economic and Social Research Council (ESRC).

Professor Mike Barnes, from UKABIF, said: "The figures suggested by this study mean action must be taken. The number of young people and adults within the criminal justice system is enormous and, as well as the anguish caused to them and their families, there is a huge cost to society to take into account."

The University of Exeter, UKABIF and The Child Brain Injury Trust have developed a special interest group which aims to improve understanding of acquired brain injury in offending behaviour.

They hope to help implement early screening for individuals within the criminal justice system and ensure access is available to appropriate rehabilitation for those who need it.

Note: If no author is given, the source is cited instead.

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