Scientists have found "profound abnormalities" in scans of brain activity in a group of retired American football players, adding to evidence indicating that repeated blows to the head can trigger longer-term aggression and dementia.
Although the former National Football League (NFL) players in the study were not diagnosed with any neurological conditions, brain-imaging tests showed unusual activity that correlated with the number of times they had left the field with a head injury during their football careers.
Adam Hampshire at Imperial College London, who led the study, said the ex-NFL players showed "some of the most pronounced abnormalities in brain activity" he had ever seen.
"And I have processed a lot of patient data sets in the past," he said in a statement about the research.
A growing body of scientific research shows that repeated knocks to the head can lead to a condition known as chronic traumatic encephalopathy, which can lead to loss of decision making control, aggression and dementia.