Do Brain Injuries Turn People Into Criminals?

S u m m a r y :
Brain injuries occurring in regions associated with morality and value-based decision-making can cause someone to incline to criminal behaviour, suggests a new study published in the Proceedings of the National Academy of Sciences.

Brain Injuries & Crime

Brain lesions can predispose people to criminal behaviour, says the new research conducted by investigators from the Vanderbilt University Medical Center. The study looks into the brain network playing a role in morality and value-based decision-making; it is the first to systematically map brain lesions linked with criminal behaviour, a condition known as acquired sociopathy.

Crime & Anti-Social Behaviour

Acquired sociopathy has been documented throughout the years, and two famous cases include a railroad worker by the name of Phineas Gage who displayed anti-social behaviour in the aftermath of an explosion that got an iron rod through his brain back in 1848, and serial killer/ brain-tumour patient Charles Whitman who killed 16 people in 1966. The new paper, on the other hand, reviews more recent cases. Led by Ryan Darby, the team investigated cases of brain lesions associated with criminality.

Looking into the Brains of Criminals

When Darby and his colleagues analysed MRI and CT scans of a group of 17 patients, they observed a definitive correlation between brain lesions and criminal behaviour. They delved into another set of 23 cases that indicated an implied correlation that had not been confirmed because the researchers did not know whether the brain lesions were before or after the criminal behaviour; these injuries were in other brain regions, but they were all connected to the same brain network.

“We looked at networks involved in morality as well as different psychological processes that researchers have thought might be involved—empathy, cognitive control and other processes that are important for decision-making,” says Darby. “We saw that it was really morality and value-based decision making—reward and punishment decision making—that the lesions were strongly connected to.”

The findings show that the lesions in patients displaying criminal behaviour appear to be more strongly related to the moral decision-making network than those lesions in patients without criminal behaviour. This suggests that the connection to this network might be specific to criminal behaviour.

“This is a relatively new approach that we have developed,” says Darby. “We have previously used it to understand other disorders where it wasn’t really clear why brain lesions in different locations caused hallucinations or delusions. In those diseases, it was also found that it was a common brain network connected to the same areas. We were the first to apply this to looking at criminal behaviour.”


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