According to research published in the Journal of the American Medical Association the Brains of 110 out of 111 deceased former National Football League Players showed signs of a disease linked to repeated hits to the head that can lead to aggression and dementia.

The findings were based on the broadest review yet of the brains of former football players for signs of Chronic Traumatic Encephalopathy. The condition, also known as CTE, is linked to the sort of head-to-head hits that were long a part of the sport, although the NFL and School Leagues have been tweaking the game in recent years to limit blows to the head.

The condition has been diagnosed in former players including hall of fame linebacker Junior Seau and Pro Bowl Safety Dave Duerson, who both committed suicide.

The researchers noted that the study had limitations including that the subjects' brains were donated by their families, and that families are more likely to opt into the study if the players had showed symptoms of CTE.