Link between brain injury and violent crime

[NEWS 28 December 2011] Epilepsy does not cause criminal tendencies, as has previously been claimed. Brain injury after a severe blow to the head, however, does double the risk of violent crime later in life, according to a new study from Karolinska Institutet and Oxford University.

Martin GrannPhoto: Kriminalvården

The study builds on previous research suggesting a possible causal link between epilepsy and brain injury, and violent behaviour. Every individual admitted to hospital with epilepsy and brain injury in Sweden between 1973 and 2009, of which a total of 2,984 were later convicted of violent crime, were each matched in terms of age and sex with ten controls from the entire population.

The results, which are published in the scientific journal PLoS Medicine, reveal that there is no such relationship between epilepsy and violent behaviour; brain injury after trauma of the head, however, was shown to double the risk of conviction for violent crime.

By comparing people with epilepsy and brain injury with their healthy siblings, the researchers were able to show that the total (epilepsy) or partial (brain injury) associations previously proposed were attributable to risk factors shared by the family (i.e. genes and childhood environment), regardless of whether or not one of these brain conditions was present.

The researchers maintain that because epilepsy and trauma-related brain injury are relatively common, it is important to investigate links to an increased risk of violent behaviour.

"It's nice to be able to dismiss former theories that people with epilepsy should show particularly violent tendencies," says Martin Grann of the Centre for Violence Prevention at Karolinska Institutet and one of the researchers involved in the study. "Epilepsy has long been a stigmatised disease and its important for people affected by it to be treated without prejudice by the healthcare services."

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