In a group of more than 100 professional football players whose brains were examined after their death, new research has found that virtually all suffered from chronic traumatic encephalopathy, a condition likely brought on by repeated blows to the head.

At a Boston University program that investigates the trauma-linked brain disease, researchers found that, of 111 former players for the National Football League who donated their brains for post-mortem examination, 110 bore the distinctive tangles, plaques and protein clumps now recognized as the neural hallmarks of CTE.

In life, all had suffered at least one of a range of behavioral symptoms — from mood instability and impulsiveness to substance abuse and aggression — that appeared to vary according to an athlete’s age at death, duration of participation in football and level of play. And the loved ones of the majority of the study’s participants told researchers that symptoms of CTE had worsened over the course of the participant’s life.

In nearly 9 out of 10 of those professional athletes — 86% — researchers found the telltale brain abnormalities of CTE were extensive, varied and scattered throughout the brain.


The report, published Tuesday in the journal JAMA, relates the accumulated findings from researchers’ post-mortem examinations of 202 brains, all donated by former football players or their families. Of those, researchers found clear evidence of CTE in 177, or 87.6%, of the brains they examined.

On average, those 177 athletes had played football for 15 years.