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Sports · North America

Study estimates CTE in nearly 75% of deceased NFL players

Boston University researchers estimate that 74.5% of NFL players who died from 2008 through 2023 had chronic traumatic encephalopathy neuropathology. They found CTE in 362 of 387 deceased players whose brains were examined and adjusted the estimate to account for the likelihood that players with symptoms were more likely to donate their brains.

AI-assisted synthesis · Based on 4 outlets' reporting · Article text read from 2 of 4 outletsHow it's made

View timeline · 6 entries
4 outletsLatest reporting 3 min read
Coverage: Mostly CenterL 0 · C 3 · R 1
Updat3 graphic: NFL
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What happened

Key facts

  • The study estimated that 74.5%, or nearly three-quarters, of NFL players who died between 2008 and 2023 had chronic traumatic encephalopathy (CTE) (per whdh.com, New York Post).
  • Researchers identified some degree of CTE neuropathology in 362 of 387 deceased NFL players whose brains were studied (per whdh.com).
  • Researchers estimated that former players with cognitive symptoms were about five times more likely to have donated their brains than players without symptoms (per whdh.com).
  • The study was led by Boston University researchers in collaboration with Mass General Brigham and the Concussion & CTE Foundation (per whdh.com, New York Post).
  • The researchers built on an August 2026 study that estimated CTE in 25% to 98% of former NFL players who died between 2016 and 2021 (per whdh.com).
  • The study was published Wednesday in JAMA Network Open (per New York Post).

The brief

A Boston University-led study estimates that 74.5% of NFL players who died between 2008 and 2023 had chronic traumatic encephalopathy (CTE), a condition linked in the study coverage to repeated head impacts. The research, published Wednesday in JAMA Network Open, found CTE neuropathology in 362 of 387 deceased players whose brains researchers examined.

The estimate applies to the larger group of deceased players, not just the brain donors. That distinction matters because the donor group may not represent all former players. Boston University said players with cognitive symptoms were estimated to be about five times more likely to donate their brains than players without symptoms.

Researchers adjusted the 94% rate observed among the 387 donors to arrive at the 74.5% estimate for the broader group. The university cautioned that donors may be more likely to have symptoms associated with CTE. Researchers from Boston University worked with Mass General Brigham and the Concussion & CTE Foundation.

The study builds on earlier work that estimated CTE prevalence among former NFL players who died between 2016 and 2021 at a range of 25% to 98%. The new estimate covers deaths across 2008 to 2023, but the available account does not describe the earlier study’s methods or explain how its range compares statistically with the new result.

The New York Post emphasized the study’s relevance to the physical demands of NFL play, opening with examples of players Aaron Donald and Puka Nacua. Its account also reported that Kelly, Matthew Stafford’s wife, called on the NFL to replace turf with natural grass across its stadiums.

That proposal is her stated position; the coverage does not report an NFL decision on the matter. The central finding is an estimate, not a count of every former player with CTE. The 362 positive findings came from examined brains, while the 74.5% figure reflects researchers’ adjustment for donor selection.

That adjustment addresses the concern that symptomatic players may be more likely to donate, but Boston University’s warning about donor representativeness underscores that the estimate depends on how well the adjustment captures differences between donors and the wider population.

The findings add a population-level estimate to evidence from donated brains and focus attention on the long-term health of former NFL players. The study does not, in the reported details, establish the prevalence of CTE among living players or quantify the condition’s effects on any particular individual.

Kelly Stafford’s call for natural grass brings a specific playing-surface proposal into the discussion, while the study’s estimate itself concerns former players who died over the studied period.

Why it matters

  • Former NFL players are the population at stake: researchers estimate CTE in 74.5% of those who died from 2008 to 2023, while identifying neuropathology in 362 of 387 brains examined.
  • Brain donation can skew the observed rate: symptomatic former players were estimated to be about five times more likely to donate, so researchers adjusted the donor finding before estimating prevalence in the wider deceased-player group.
  • The study’s estimate may inform discussion of former players’ health, but it does not measure CTE prevalence among living NFL players or the condition’s effects on individual players.
  • Kelly Stafford’s proposal would change NFL playing surfaces from turf to natural grass; the coverage reports her call but no league decision.

What to watch next

  • Whether the NFL addresses Kelly Stafford’s call to replace turf with natural grass across its stadiums.
  • Whether Boston University, Mass General Brigham or the Concussion & CTE Foundation publish further analysis of the 74.5% estimate or its adjustment for donor selection.
  • Whether subsequent research tests the estimate against additional evidence on CTE among deceased former NFL players.

How it's being covered

Coverage analysisShow details
4 source articles · 4 unique outlets
Outlet political mix: Mostly Center· 3 Center · 1 Right
Where the outlets are based: US/Canada 75% · Unknown 25%
Outlet political mix
Mostly Center
Left
Center
Right
0 outlets
3 outlets
1 outlet
The marker shows coverage balance: each unique outlet counts once.
Geography
Where the outlets covering this story are based.
4 unique outletsDominant coverage: US/Canada
Coverage imbalance
  • Coverage is currently concentrated among Center-rated outlets (3 of 4 rated sources); comparatively few Left-rated outlets have published on the event.
  • Coverage is currently concentrated among outlets based in US/Canada (3 of 4 geographically-identified sources).
How we measure coverage

How outlets' accounts compare

2 framing differences · 2 uncorroborated claims · 1 information gap
The reports repeat the same account with different emphasis; its central claims are not independently confirmed in the reporting Updat3 read.Compared across 2 reports whose article text Updat3 read; 2 other outlets were checked by headline only.
Framing / emphasis differences
Sources emphasise different angles, actors or consequences of the same reporting.
  • WHDH focuses on the estimate, the brain-donor sample and the adjustment for selection bias; the New York Post foregrounds NFL players and adds Kelly Stafford’s call for natural grass.
  • Boston University cautions that brain donors may be more likely to have CTE-associated symptoms; the reported estimate therefore depends on an adjustment for differences between donors and the wider group.
Updat3: These are differences of emphasis, not disputes about what is reported. They do not show that the reported claims are true.
One-sided or uncorroborated claims
Claims that come from one party or one source family and are not independently corroborated.
  • Boston University’s reported estimate is that former players with cognitive symptoms were about five times more likely to donate their brains than players without symptoms.
  • Kelly Stafford called for the NFL to eliminate turf fields and install natural grass surfaces across its stadiums.
Updat3: Not independently corroborated yet — treat as a claim, not an established fact.
Not established by the reporting
Information the available reporting does not contain or confirm. This is a gap, not a disagreement.
  • The sources do not provide the underlying records or details needed to assess independently how the donor-selection adjustment was calculated.
Updat3: Updat3 cannot conclude anything about this from the current sources.

Timeline

Developments from this story's sources, dated background we compiled and fact-checked, and our earlier coverage. Each row says which.
  1. The modern study of CTE in football gained a landmark case in 2005, when neuropathologist Bennet Omalu published findings of CTE in the brain of former Pittsburgh Steelers player Mike Webster.
    Background · from our historical context
  2. In 2008, Boston University established its CTE Center, which worked with the Sports Legacy Institute to study donated brains.
    Background · from our historical context
  3. In 2013, the NFL agreed to a settlement of concussion-related lawsuits brought by former players, without admitting liability.
    Background · from our historical context
  4. In 2016, the NFL acknowledged a link between football and CTE.
    Background · from our historical context
  5. Boston University researchers had previously estimated in 2018 that CTE affected 99% of former NFL players whose brains had been donated to its research program; that sample was not representative of all former players.
    Background · from our historical context
  6. The researchers built on an August 2026 study that estimated CTE in 25% to 98% of former NFL players who died between 2016 and 2021.
    Reported in this story's sourcesSource:whdh.com

How we got here

In August 2026, a study estimated that chronic traumatic encephalopathy (CTE) was present in 25% to 98% of former NFL players who died between 2016 and 2021, a wide range reflecting uncertainty in estimating prevalence from donated brains.

Boston University researchers had previously estimated in 2018 that CTE affected 99% of former NFL players whose brains had been donated to its research program; that sample was not representative of all former players.

Original sources

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