Head injury can dramatically increase the chances of someone committing violent crime, a study has found.
In a large group of 22,914 traumatic brain injury victims, almost 9% went on to commit acts of violence after diagnosis.
Compared with the general population, people with brain injuries were three times more likely to perpetrate violent crimes.
To carry out the investigation, British and Swedish authors matched every case of epilepsy and traumatic brain injury recorded in Sweden between 1973 and 2009 with 10 people free of these conditions.
The study was the largest of its kind ever carried out with both the brain injury and epilepsy groups, totalling more than 22,000 people.
It found that 8.8% of the brain injury group were convicted of violent crime after diagnosis compared with just 3% of the general population. The findings were published in online journal Public Library of Science Medicine.