Study: Estimated 75% of NFL players who died between 2008 to 2023 had CTE

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  Shwetha SurendranOct 28, 2026, 07:02 PM ET

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  Shwetha Surendran is a reporter in ESPN's investigative and enterprise unit.

An estimated 75% of former NFL players who died between 2008 and 2023 had chronic traumatic encephalopathy, or CTE, the neurodegenerative brain disease tied to high-impact sports like football, according to a new study released Wednesday.

The study, published in JAMA Network Open by researchers at Boston University, Mass General Brigham and the Concussion & CTE Foundation, said it marked the first comprehensive effort by scientists to understand the prevalence of CTE among deceased former NFL players.

Some of the same researchers published a paper in August that estimated that one in four former NFL players who died between 2016 and 2021 had CTE.

The neurodegenerative disease is currently only diagnosable after death, and the research into finding a CTE test during life is ongoing.

The researchers cautioned that the estimate only applies to deceased NFL players and does not predict the prevalence of CTE in living NFL players. The study also doesn't address prevalence among college or youth football players. Among other caveats were that the study doesn't indicate what, if any, symptoms of CTE had manifested in the players that might have been related to.

CTE is identified in stages ranging from I to IV based on severity. Symptoms often don't manifest in the earliest stages, according to researchers.

"Many cases may have been early stage at the time of death and possibly symptom free," the paper said.

Julia Gallini, the lead author on the paper, said in a statement that the nearly 75% estimated prevalence was "concerning" and that more effort needed to be made "to support families, diagnose CTE during life, and treat CTE-related symptoms."

Past research into CTE has drawn criticism for selection bias, because of its reliance on brains donated by players who were more likely to have symptoms while alive.

The study involved 2,362 cases. It combined data from 396 players who donated their brain and the National Death Index records of the 1,966 deceased players who didn't donate.

Compared to the non-donors, donors in the study were more likely to be white, to have died younger and to have played longer in the NFL. Nearly 94% of the donated brains had CTE.

"Even after accounting for differential brain donation, our findings suggest that the prevalence of CTE among deceased NFL players remains high," the paper said.

Questions still remain about the prevalence of CTE in the lower levels of football at the high school or college level. Researchers noted the lack of data on non-donors at lower levels of play as challenges to the research in youth tackle football.

The NFL, in a statement, said the league "continuously strives to make the game of football safer, including by implementing strategies to reduce concussions and head impacts. ... We encourage former players to utilize these resources to identify and seek treatment when they are concerned about their health."

The NFL Players Association said such studies "are critical to improving our understanding of football's long-term impacts."