Study: Quarter of Dead NFL Players Had CTE

That extraordinary range reflects a methodological limit: the 235 donated brains cannot be assumed to represent all 878 men, so the team had to model the players who were never examined. Daniel Daneshvar, the study's lead author and chair of physical medicine and rehabilitation at Mass General Brigham, said the real prevalence "likely lies somewhere in the middle", noting that community brain banks find CTE in under one percent of the general population. The study also traced consequences: 61.3 percent of donors diagnosed with CTE also qualified clinically as having dementia, and roughly 90 percent of those with the most advanced form, Stage IV, had received a dementia diagnosis. According to Daneshvar, what predicts the disease most strongly is the accumulated force of repeated head impacts.

The NFL said it "continuously strives to make the game of football safer" and is expanding health resources for retired players. The NFL Players Association (NFLPA) called the findings "a sobering reminder that football carries real risks" and urged better research, care and treatment. Attention is now shifting to younger athletes. Daneshvar recommends keeping children out of tackle football and removing contact from practice sessions, and the authors say prevention should target repetitive head impacts rather than concussions alone. Teena Shetty, a neurologist interviewed by NPR (National Public Radio), said the graver danger may lie in subconcussive blows that never prompt a medical visit, particularly while the brain is still developing. American high schools have improved considerably, she said, but only the injured player can reliably report symptoms, which makes awareness essential.