Mike Webster, the Hall of Fame center of the Steelers’ four Super Bowl teams of the 1970s, died in 2002 at 50. Pathologist Bennet Omalu examined his brain and, in 2005, published the first description of chronic traumatic encephalopathy in a former NFL player.

CTE is a degenerative brain disease linked to repeated head impacts. It can only be confirmed after death.

1. 2002Mike Webster dies at 50
2. 2005Omalu publishes the first CTE case report in a former NFL player
3. Oct. 28, 2009Commissioner Roger Goodell is questioned about brain injuries at a House Judiciary Committee hearing
4. 2013The NFL agrees to a $765 million settlement with former players over concussions. A judge later approves an uncapped version
5. March 2016League executive Jeff Miller acknowledges a link between football and CTE at a congressional roundtable
6. Oct. 28, 2026The new estimate is published: 74.5%

For years, the headline numbers came from the brain bank run by Boston University. In 2017, researchers there found CTE in 110 of 111 former NFL players they examined. In 2023, the count was 345 of 376.

Critics had a fair point. Families who saw memory loss, mood changes or dementia in a former player were more likely to donate his brain, so the bank was never a random sample.

Share of examined brains with CTE

The new study, led by Boston University biostatistics PhD candidate Julia Gallini and professor Yorghos Tripodis with Mass General Brigham and the Concussion & CTE Foundation, went past the brain bank. It pulled federal death records for every former NFL player who died from January 2008 through December 2023.

That gave the researchers 2,362 players: 396 brain donors and 1,966 men whose brains were never studied.

Then they compared the two groups by cognitive symptoms, age at death, position and years in the league. Players with cognitive symptoms were about five times as likely to have their brains donated. That ratio, 4.97, is what the researchers used to scale the donor rate down to an estimate for everyone.

From the brain bank to the whole group

The estimate’s statistical range runs from 69.6% to 78.3%. In August, the same research group had looked at 878 players who died from 2016 to 2021 and could only say the true figure was at least 25%, with an upper limit near 97%. The new method narrows that gap.

The researchers were careful about the limits. The 74.5% applies only to former players after death. It does not predict how many living former players have CTE, and it says nothing directly about active players. Not everyone with signs of the disease develops symptoms.

The donors were also different from the rest: more likely to be white, to have died younger and to have played longer in the league. The adjustment accounts for cognitive symptoms and those other factors, but the authors still call for more research on what the disease does in life.

The league points to padded Guardian Caps in preseason practices since 2022, newer helmet models and the dynamic kickoff. Its own numbers for the 2025 regular season show the trade-offs: game concussions went up from 129 to 168, and kickoff concussions rose from 8 to 35 as the new rules more than doubled the number of returns.

Concussions in regular-season games