Study estimates about three in four NFL players who died in 2008–2023 had CTE

Compiled from reports by NBC News and ABC7 Chicago. See the original articles linked below.

This article reports news and is not medical advice.

A new research paper estimates that about three out of every four former National Football League players who died between 2008 and 2023 had chronic traumatic encephalopathy, known as CTE. NBC News and ABC7 Chicago both reported on the findings on October 28, 2026.

What the study examined

NBC News reported that the work appeared in JAMA Network Open and was led by Yorghos Tripodis of Boston University. ABC7 Chicago described the publication as the Journal of the American Medical Association, so the two outlets name the journal differently. According to ABC7 Chicago, the researchers looked at 2,362 former players who had died during the period, and 396 of them had donated their brains for examination. ABC7 Chicago said 93.5% of those donors were found to have CTE.

NBC News said the team combined information from the donated brains with death records covering 1,966 other former players. Using that combined data, the researchers estimated that around 1,760 of roughly 2,360 players, or nearly 75%, had the disease. ABC7 Chicago gave the adjusted figure as 74.5%.

Adjusting for who donates

Both outlets explained that CTE can currently be confirmed only after death. NBC News reported that families of players who showed cognitive decline are more likely to donate a brain, which the authors say pushed up earlier estimates. ABC7 Chicago likewise said the researchers corrected for the chance that families who noticed symptoms were more inclined to donate. An author was quoted by ABC7 Chicago as saying no study of this kind can remove every possible bias.

Dementia estimate

NBC News reported that the study estimated about 27% of the former players had dementia. ABC7 Chicago gave a figure of 27.2% for dementia during the players' lifetimes and said the researchers believe this probably understates the true share. NBC News added that not everyone with signs of CTE in the brain goes on to develop dementia, and some may never have symptoms.

Earlier work and limits

Both outlets said an August study by many of the same researchers had estimated that at least one in four former players who died over a shorter span had CTE. ABC7 Chicago said that study covered deaths from 2016 to 2021 and could only point to a broad range. It said the new paper aims to narrow that range. NBC News described the latest figure as the highest estimate to date.

ABC7 Chicago reported that the authors caution the results apply to deceased former players and may not represent those who are currently playing. NBC News quoted Tripodis as saying that doctors do not yet know how to diagnose CTE in living people, which is why the team relied on estimation.

Responses from the league

NBC News reported that the NFL said it works to make the sport safer, pointing to efforts to reduce concussions. The outlet noted changes such as redesigned helmets and a dynamic kickoff rule. According to ABC7 Chicago, the NFL and the NFL Players Association each issued statements that stressed player safety, support for research and access to care.

NBC News also reported that Tripodis argued reducing impacts to the brain is the principal way to lower the risk of the disease.

Sources

This article was compiled with AI assistance from the reports listed above and reviewed by GMA before publishing.