Study Finds CTE in at Least 1 in 4 Former NFL Players Who Died

At least one in four former NFL players who died between 2016 and 2021 had chronic traumatic encephalopathy, or CTE, according to a major study published Tuesday. The research, which provides the most comprehensive estimate to date of the degenerative brain disease's prevalence among retired players, found the condition in over 90% of the donated brains examined, with the true rate likely falling somewhere between 24.5% and 97.7%.

The study, published in the British Medical Journal, was conducted by researchers from Mass General Brigham, Boston University, and the Concussion CTE Foundation. It examined the period from 2016 to 2021, when brain donations from deceased former players were most frequent. Of the 878 former NFL players who died during that five-year span, 235 donated their brains for analysis. Researchers found CTE in 215 of those brains, a rate of 91.4%.

Because CTE can only be definitively diagnosed after death through brain tissue examination, and not every deceased player donates their brain, the researchers calculated a range for the true prevalence. The most conservative estimate, assuming only the donated brains represented cases, is 24.5%. The upper extreme,...