At least one in four former National Football League players who died between 2016 and 2021 had chronic traumatic encephalopathy at death, according to research published in The BMJ. The researchers describe 24.5 percent as a minimum, not a midpoint, and calculate that the true figure could run as high as 97.7 percent.
The study is the first serious attempt to place a population denominator under the CTE question. Previous estimates came almost entirely from donated brains, a group skewed toward families who already suspected the disease. This team, from Mass General Brigham, Boston University, and the Concussion and CTE Foundation, started instead with a roster of former players from the hard-shell helmet era.
