A new NFL CTE study is putting a hard number on something football has spent two decades dancing around. At least one in four former NFL players who died between 2016 and 2021 had chronic traumatic encephalopathy, the degenerative brain disease caused by repeated hits to the head, according to research published Tuesday in The BMJ. The finding comes from one of the most detailed CTE prevalence studies to date, and it lands at a moment when the league is bigger, richer, and more culturally dominant than ever, while the players absorbing the hits are still waiting on real answers about what football does to the brain over a lifetime.
The team behind the NFL CTE study, made up of researchers from Mass General Brigham, Boston University, and the Concussion and CTE Foundation, looked at every former NFL player who died during that six-year window. That group totaled 878 men, some who passed in their twenties and some in their eighties. Of those, 235 families donated brains for examination, and 215 of those brains, or 24.5 percent, showed evidence of CTE. According to ESPN, that 25 percent figure only reflects the players whose brains were actually studied, meaning researchers still have no data on the other 643 men who died in that period. The concern, as several scientists involved in the work have pointed out, is that the true rate across the full population of former players could be considerably higher than what the data currently shows.
The full scope of the research goes back further than just that six-year window. Per ABC News, the broader study examined 1,712 former players who died between 2008 and 2021, with 338 brain donations among them. Of those donated brains, 315, or 93.2 percent, showed signs of CTE. The disease is caused by an “abnormal buildup of tau protein that damages brain cells,” which over time can affect memory, mood, and behavior. Nearly 60 percent of the brain donors in the study also had dementia, and among those with the most advanced form of the disease, stage four CTE, more than 90 percent had dementia by the time they died. Researchers noted that stage four CTE was linked to a 44 percent higher risk of dementia even after accounting for differences between the men who donated their brains and those who did not.
Dr. Daniel Daneshvar, the study’s lead author and chair of physical medicine and rehabilitation at Mass General Brigham, has spent years studying the long-term effects of repetitive head trauma in football. Speaking with CBC News, he said the team was “surprised but saddened to see that the minimum rate was so alarmingly high.” That framing matters, because Daneshvar and his colleagues are clear that 24.5 percent is a floor, not a ceiling. It is the lowest possible estimate given how many former players never had their brains examined at all.
This NFL CTE study also arrives with important context about who is actually carrying this risk. According to Statista, more than 53 percent of NFL players are Black, a share that has held steady for years and puts Black men at the center of every conversation about football-related brain injury, retirement health, and life expectancy after the league.
When a brain disease shows up in a quarter or more of a population, and that population is disproportionately Black fathers, sons, husbands, and community figures, the ripple effects run through families and neighborhoods long after the final whistle. The generational wealth football has helped build in Black communities has always come with a physical cost that rarely gets discussed with the same energy as contract numbers and Hall of Fame votes.
The NFL, for its part, is standing behind its safety record. A league spokesperson told NBC News the organization “continuously strives to make the game of football safer” and pointed to ongoing investment in resources for players’ physical and mental health. Some researchers not directly involved in the study urged a bit of caution about applying these numbers to today’s game. Dr. Russell Chesnut told NPR that because the players studied were largely from an earlier era, before rule changes and concussion protocols matured, “this may not represent the NFL in 2026.” Still, an editorial published alongside the research and cited by CNN called it “one of the most informative estimates to date of CTE burden” among former NFL players, precisely because of how large and how carefully tracked the sample was.
None of this is coming out of nowhere. Boston University researchers made headlines back in 2023 when they found CTE in 345 of 376 brains studied, a staggering 92 percent, though that sample leaned heavily toward players and families who already suspected something was wrong and chose to donate. What makes this newest NFL CTE study different, according to Medical Xpress, is that it tried to capture a more complete population of players rather than only those who came forward, which is part of why the 24.5 percent floor carries so much weight with researchers.
CTE cannot be diagnosed while someone is alive. It shows up only after death, through brain tissue analysis, which means every player walking off the field today is carrying an unknown. Symptoms, when they eventually surface, can include memory loss, mood swings, impulse control issues, and depression, often appearing years or even decades after a career ends.
Researchers behind the study are urging prevention strategies that reduce repetitive head impacts across every level of football, not just the professional ranks, since the damage tied to CTE accumulates long before a player ever sees an NFL contract.
