Study: 75% of Ex-NFL Players Who Died Between 2008 and 2023 Had CTE
Nearly 75% of all National Football League (NFL) players who died between 2008 and 2023 had chronic traumatic encephalopathy (CTE) neuropathology, according to a new study led by Boston University.
The new findings build on an August 2026 study from the same research group that estimated that between 25% and 98% of former NFL players who died between 2016 and 2021 had CTE.
Researchers cautioned that the new study’s estimate of prevalence only applies to former NFL players after death. It does not predict how many living former players have CTE or how many active players are impacted.
The wide range in the earlier study reflected uncertainty about how representative brain donors were of the overall NFL population. Brain donors are more likely to have symptoms believed to be related to CTE, a concept known as selection bias.
The earlier research drew some criticism for that selection bias because it relied upon brains donated by players who were more likely to have had symptoms while alive.
The researchers addressed that selection bias in the latest study. They looked at 2,362 cases that included data from 396 players who donated their brain along with data from National Death Index records of 1,966 deceased players who did not donate.
The new study, a collaboration among researchers at Boston University, Mass General Brigham (MGB) and the Concussion & CTE Foundation, was published in JAMA Network Open.
CTE is a neurodegenerative disease that has been diagnosed in individuals with substantial exposure to repetitive head impacts. It can only be definitively diagnosed after death.
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“Providing a precise estimate for the prevalence of CTE among deceased NFL players helps define the scale of the problem and informs priorities for the potential current and future medical needs of this community,” said Julia Gallini, lead author and a PhD candidate at Boston University School of Public Health. “With CTE consistently found in less than 1% of donors to community brain banks, an estimated 75% prevalence among NFL players who died over a 16-year period is concerning, and suggests we need to increase efforts to support families, diagnose CTE during life, and treat CTE-related symptoms.”
The researchers noted that not every player with CTE pathology will go on to develop symptoms, particularly in cases of early-stage disease. Among players who do develop symptoms of CTE, cognitive impairment, behavioral changes and dementia are some of the common signs.
They said previous studies have shown NFL players develop dementia at four times the rate of the population.
Another study published this summer in the British Medical Journal found that of the 235 athletes whose brains were subject to postmortem neurological examinations, 215 had confirmed CTE.
In statements to ESPN, the NFL said the league continues to implement strategies to reduce concussions and head impacts and the NFL Players Association called such research critical to improving understanding of football’s long-term impacts.
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Matt Hasselbeck, an 18-year NFL veteran who serves as the ambassador for the DIAGNOSE CTE study and who has volunteered for research, said the new research is important. “We have to learn from this data to make the game safer, because we can’t accept these numbers for the next generation of players,” Hasselbeck said.
In 2013, the NFL agreed to an $765 million settlement of a lawsuit by retired players who claimed the NFL had failed to share what it knew about the long-term effects of head trauma.
In 2018, the National Hockey League reached a similar $19 million settlement with more than 300 retired players.