Shocking CTE Rate Rocks NFL

A new medical study says at least one in four NFL players who died between 2016 and 2021 had a brain disease usually tied to repeated hits to the head.

Quick Take

A study in The BMJ found at least 24.5% of 878 former NFL players who died from 2016 to 2021 had chronic traumatic encephalopathy, known as CTE, at death.
Researchers examined 235 donated brains out of those 878 deaths and found CTE in 215 of them, a rate of 91.4% among donors.
The true rate across all deceased players could run as high as 97.7%, since most brains were never examined.
Scientists warn the sample may skew high because families who suspect brain trouble are more likely to donate a loved one’s brain for study.

What The Numbers Actually Show

The study, led by researchers connected to Mass General Brigham and Boston University, tracked 878 former NFL players who died over a five-year window. Families donated 235 of those brains for examination. Pathologists found CTE in 215 of them, a striking 91.4% rate among donated cases. The authors then built a conservative floor of 24.5% by assuming none of the un-examined brains had the disease at all.

That floor matters because it treats every unexamined death as a clean brain, which nobody actually believes is true. The study’s authors say the real prevalence likely sits somewhere between that 24.5% floor and a 97.7% ceiling, with the true number probably in the middle. Peer-reviewed publication in The BMJ, one of the world’s oldest medical journals, gives the finding real scientific weight.

Why The Sample Isn’t The Whole Story

CTE can only be confirmed after death, so scientists depend on donated brain tissue. That creates a built-in problem. Families who already suspect something was wrong with a father, husband, or son are far more willing to hand over his brain for research. Boston University’s own researchers have flagged this exact issue for years, warning that donor samples are not a random slice of all football players.

ESPN reported that researchers themselves admit their work carries a “tremendous selection bias,” since it’s built on players whose families were already worried enough about cognitive decline to donate. A separate peer-reviewed analysis found that after adjusting for this bias, the risk actually increased rather than decreased, suggesting earlier estimates may have understated the danger rather than overstated it.

What This Means For Families And The League

The debate here isn’t really about whether CTE exists in football players. Nobody credible disputes that repeated head trauma damages the brain over time. The real fight is over how big the problem is and how confidently anyone can put a number on it. A range stretching from 24.5% to nearly 98% leaves plenty of room for spin in either direction, and that ambiguity should worry parents more than comfort them.

A disease found in over 90% of donated brains, even with selection bias baked in, is not a fringe concern. The NFL has spent years tightening concussion protocols and limiting full-contact practices, and this study gives fresh weight to arguments that those changes needed to happen. Families deciding whether to let kids play tackle football deserve straight numbers, not headline math stripped of context.

The Limits Science Still Faces

No living-player test for CTE exists yet, so doctors cannot tell a current player whether he’s already developing the disease. That gap lets institutions argue for more research before making big policy changes, even as evidence piles up. The Athletic noted the 24.5% figure only holds “if none” of the unexamined brains had signs of disease, a assumption almost certainly too generous.

Until researchers find a way to diagnose CTE in the living, or build a broader, less biased sample of deceased players, this debate will keep circling the same numbers. What’s clear is that the disease is common enough among donated brains that dismissing it as rare or overblown doesn’t match the evidence. The honest answer sits in the uncomfortable middle ground the study’s own authors describe.

Thread grounded: A study estimate that one in four former NFL players developed CTE sparked debate over sampling bias and the true prevalence.

Sides
• Misleading headline: The sample cannot represent every former NFL player.

• Understated risk: The donated brains showed CTE…

— BREAKLING (@BREAKLINGx) August 28, 2026

Parents, coaches, and league officials now face a harder question than before: not whether football carries brain-injury risk, but how much risk is acceptable and what changes are still needed to reduce it further.