New Study Finds At Least One in Four Former National Football League (NFL) Players Had Chronic Traumatic Encephalopathy (CTE)

A research team from Mass General Brigham, Boston University and the Concussion & CTE Foundation examined 235 brains of former NFL players who died between 2016 and 2021. Of those, 215 were diagnosed with CTE. Using the total of 878 former players who died in that period, the investigators calculated a minimum prevalence of 24.5 %—roughly one in four former players. Assuming every non-donated brain (except 20 cleared cases) contained CTE, the maximum possible prevalence rises to about 97 %. Lead author Dr. Daniel Daneshvar says the true rate “is somewhere in the middle.”

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CTE is a progressive neurodegenerative disease linked to repeated head impacts. Earlier brain-bank studies reported very high rates of CTE among donated NFL brains but lacked a denominator. This study combined a near-complete roster of former players with CDC death-certificate data, providing the first population-based prevalence estimate for the modern era.

Study finds CTE in at least 1 in 4 former NFL players who died between 2016-2021 At Least 25 Percent of Former NFL Players Had CTE When They Died, New Study Suggests CBS SportsNPRForbes

• 878 former NFL players died 2016–2021.

Sports Illustrated

• 235 brains donated; 215 (? 91 %) showed CTE pathology.

Bleacher Report

• Minimum prevalence: 24.5 %.

Forbes

• Upper bound: ? 97 % if all non-donors except 20 cleared cases had CTE.

CBS Sports

• Dementia correlation: > 90 % of Stage IV CTE cases also had clinical dementia; overall, 61.3 % of CTE donors met dementia criteria.

CBS Sports

• General-population baseline: Community brain-bank studies show CTE in < 1 % of people without repeated head trauma.

WBUR - NPR - Boston

The findings frame professional football as an occupational health hazard with prevalence far exceeding that of asbestos-related diseases. Most head impacts occurred outside the NFL, during high-school, college and youth play, suggesting safety reforms must extend to all levels. If prevalence approaches the upper estimates, the long-term medical burden on former players and families could be substantial, potentially influencing youth participation and prompting broader public-health interventions.

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• Former OSHA chief Doug Parker remarked, “I don’t think that this would be abided in any industry,” highlighting the unprecedented scale of the risk.

NBC Sports

Researchers note a key limitation: brain donation is symptom-driven, meaning families of players with neurological problems were more likely to donate, which could inflate estimates. The authors therefore present a range rather than a single figure and call for additional data from non-donors.

CNN

• Prevalence range: 24.5 % – 97 % reflects uncertainty about non-donated brains.

Forbes

• Diagnostic gap: CTE can only be confirmed post-mortem; no validated test exists for living individuals.

NPR

• Historical bias: Most donated brains belong to players whose careers ended before 2005, leaving open the question of how current safety measures affect risk.

CNN

• “We've known that this disease process can be caused by, in part, repeated traumatic brain injury. But we didn't know how common it was,” — Dr. Daniel Daneshvar

NPR

• “The ?bulk of the head impacts that these former NFL players experienced didn’t occur at the NFL level. They occurred at the collegiate level … and at the high school level and in many cases the youth level. And all of those cumulative hits to the head added up to result in an increased risk,” — Dr. Daniel Daneshvar

CNN

• “I don’t think that this would be abided in any industry,” — Doug Parker

New York Times

• “The true rate of CTE at death in NFL players is somewhere in the middle,” — Dr. Daniel Daneshvar

NPR

The team plans to apply the denominator approach to former college players and to conduct geospatial analyses of head-impact exposure across counties.

CNN