Researchers find alarming rates of CTE in former football players

In a new study from Mass General Brigham, Boston University (BU), and the Concussion & CTE Foundation, researchers found evidence that at least 1-in-4 former NFL players who died between 2016 and 2021 had chronic traumatic encephalopathy (CTE) at the time of their death, a much higher prevalence compared to the general population. Researchers also found that 61.3% of NFL donors with CTE met clinical criteria for dementia, with severe CTE more frequently associated with dementia. Results were published today in The BMJ.

Currently, CTE can only definitively be diagnosed after death through examination of brain tissue. To estimate prevalence, researchers identified all former NFL players from the hard-shell helmet era who died between 2008 and 2021. Between 2016 and 2021, the highest donation period, 878 former NFL players died. Of those players, 235 donated their brains, and 215 (91.4%) of the donated brains were found to have CTE.

The majority of brains analyzed were donated to the UNITE Brain Bank at the Boston University CTE Center, with additional donations included from the Mount Sinai and University of California San Francisco Alzheimer's Disease Research Center brain banks. To account for players who did not donate their brains, researchers estimated a range for possible CTE prevalence. The most conservative estimate assumes that the 215 confirmed cases were the only cases of CTE among all 878 deceased players, resulting in a prevalence of 24.5%, or about 1-in-4 former NFL players.

The opposite extreme-that every player who did not donate their brain also had CTE-means that up to 97.7% of players in that study period could have had CTE, although both extremes are highly unlikely. The true prevalence likely lies somewhere in the middle.