Young adults who've suffered head injuries are more likely to get into a fight or take part in other kinds of violence, according to new study findings. The link between head injury and violence was particularly strong if the previous head injury had occurred within the past year, the authors note in the journal Pediatrics.
With this type of research, it's never possible to figure out if brain injuries really are at the root of aggression, or if some other factor is behind both, study author Dr Sarah Stoddard of the University of Michigan, Ann Arbor, told Reuters Health.
But things like drug use, heavy drinking and a history of violence didn't seem to explain the findings, she said. According to the US Centres for Disease Control and Prevention, some 1.7 million Americans experience a traumatic brain injury every year, due to bumps, blows, jolts, or any injury that disrupts the brain's normal functioning.
Most brain injuries are mild, leading to a short loss of consciousness or confusion. When severe, however, they may cause amnesia and long periods of unconsciousness.
Previous work has shown that brain injuries can also cause changes in memory, reasoning, and emotions, including impulsivity and aggression. In studies with prisoners, researchers have found that those with a history of brain injuries are more likely to engage in violence.
To investigate whether the same relationship exists in non-prisoners, Stoddard and a colleague analysed several years' worth of data from 850 high schoolers, following them until five years after they left school.
All of the participants had a grade point average of 3 or lower, putting them at risk for dropping out.
In the fifth year of the study, 88 of the young adults said they had suffered a head injury. Of those individuals, 43 percent said they had gotten into a fight, hurt someone, or taken part in some type of violence over the following year. That compared to 34 percent of those who didn't report a head injury.
The findings hint that the more recent a head injury is, the more likely a young adult is to be aggressive. According to Stoddard, "The brain does recover over time."
She said researchers should investigate the long-term effects of head injuries in young people, as well as preventive measures such as protective gear for sports and interventions that help kids with head injuries manage their behaviours before they lead to violence.