A new study provides further evidence that a history of traumatic brain injury (TBI) may be linked with an increased risk of committing criminal acts. According to a report published in PLOS ONE, an Australian research group has found a modest increase in the risk of committing a criminal offence, including violent offences, following a hospital-documented TBI.
Past research has consistently found heightened rates of traumatic brain injuries among criminal offenders. This has led some neuroscientists to suggest “many offences may be a consequence of TBI-related behavioral dysregulation,” as the authors of the latest study note in their introduction.
To further explore this idea, the team of researchers reviewed administrative data collected by the Western Australia Departments of Health and Corrective Services and the Western Australia Drug and Alcohol Office. To start, the team identified individuals born between 1980 and 1985 whose hospital records included a documented TBI. The researchers then matched and compared each individual identified with three randomly-selected people of the same sex and birth year as well as one same-sex full-sibling if one was available. None of these control participants had a record of TBI.
Out of 136,100 individuals born in Western Australia within the specified years, the team included 7,694 individuals with a history of TBI in the study (5,018 males and 2,676 females) with an average age at first TBI of 10.6 years old for the boys and 6.9 years old for the girls.
Compared to their matched “controls”, past TBI sufferers had twice the rate of both criminal convictions and mental illness. The rate of conviction was almost 18 percent among males with a record of TBI, compared with 10 percent among males without a brain injury history. Among women, the rate was nine percent for those with a documented TBI and four percent for those without.
“The results from the current study would be consistent with a causal relationship between TBI and subsequent criminal convictions, and convictions for violence in particular, in both sexes,” noted the authors in their conclusion.
The researchers also found rates of mental illness were as high as 19 percent among males with a history of TBI, compared to nine percent for males without. Similarly, 22 percent of women with histories of TBI had a diagnosis of mental illness, compared to only 13 percent of females without TBI.
The findings bring the researchers to suggest future studies attempt predictive models that will help explain the complex relationship between traumatic brain injuries and criminality, as well as exploring gender and ethnic differences, maternal and birth characteristics, and age at time of brain injury.