A new study of former NFL players who died between 2016 and 2021 found at least a quarter had chronic traumatic encephalopathy (CTE), the degenerative brain disease linked to repeated head impacts, according to NPR. The study offers some of the most comprehensive data yet on CTE’s true prevalence among NFL veterans — a question that has remained contested because CTE can only be diagnosed definitively after death through brain tissue examination.
WHY THIS STUDY IS DIFFERENT
Prior CTE research faced a specific methodological limitation: the brains studied were typically donated by families who suspected their loved ones had the disease, creating selection bias — the sample was not representative of all NFL players because it over-represented players whose families had CTE suspicions. A study of all former NFL players who died in a specific period — rather than only those with brain donations — provides a more representative sample, even if brain examination was only possible for a subset.
WHAT 25 PERCENT ACTUALLY MEANS
The 25 percent figure requires careful interpretation:
▸ It is a minimum: the study found CTE in at least a quarter of the examined players; the actual rate among all former NFL players who died in the period is unknown because not all brains were available for examination
▸ Position and career length matter: CTE risk is not uniform across all NFL positions; linemen who experience repeated high-force collisions are at higher risk than kickers or punters; longer careers expose players to more cumulative impacts
▸ CTE severity varies widely: the disease exists on a spectrum from mild to severe; not all CTE-positive players experienced the most severe cognitive and behavioral symptoms
▸ Causation is established but individual prediction is not: we know repeated head impacts cause CTE; we cannot predict which individual players will develop the disease
THE LEAGUE’S RESPONSE
The NFL has increasingly acknowledged the link between football and CTE since the 2016 congressional testimony in which a league official for the first time publicly acknowledged the connection. The league has implemented rule changes aimed at reducing high-impact collisions, required concussion protocol adherence, and funded research. Critics argue the changes are insufficient relative to the fundamental physics of the sport: football, as played at the professional level, involves repeated high-force head impacts that no rule change can eliminate.
CTE can only be confirmed after death. The study found it in at least a quarter of former NFL players who died in a five-year period. The true prevalence is unknown because not every brain can be examined. The number we have is a lower bound.
THE YOUTH FOOTBALL DIMENSION
The CTE research has downstream implications for youth football, where millions of children play and where brain development is still occurring. Several states and school districts have implemented tackle football bans for young children based on CTE research; the NFL’s own messaging has begun to recommend flag football for children under 14. Whether the 25 percent finding accelerates those recommendations is the specific policy question the study raises.
WHAT HAPPENS NEXT
▸ Peer review and replication — the study’s methodology will be assessed by independent researchers
▸ NFL rule change discussion — the finding will be cited in future discussions of player safety rules
▸ Youth football policy — whether state and local policies limiting youth tackle football are accelerated
▸ Legal implications — ongoing litigation between former players and the NFL over CTE-related health damages
| CONFIDENCE: HIGH | New study finding CTE in at least a quarter of former NFL players dying between 2016 and 2021 is from NPR confirmed reporting. CTE diagnosis methodology (post-mortem only), selection bias in prior research, and NFL position risk differentiation are from established medical literature. |
| ⚖️ BIAS CHECK — WHO IS SAYING WHAT | |
| Study Researchers | Providing the most comprehensive population-based CTE prevalence data available; their methodology is more representative than prior donation-based studies |
| NFL | Will note rule changes and safety improvements; will not accept the implication that professional football is incompatible with brain health |
| Former Players and Families | Have specific personal stakes; families who have experienced CTE outcomes will see validation in the study; others will note the individual variation in outcomes |
| Youth Sports Community | The policy implications for youth football are real; parents, coaches, and administrators will assess the 25 percent figure against their programs |
SOURCES
▸ NPR — NFL CTE study former players 2016-2021, August 26, 2026
Q: What is CTE?
A: Chronic Traumatic Encephalopathy (CTE) is a degenerative brain disease caused by repeated head impacts. It can only be definitively diagnosed post-mortem through brain tissue examination for specific tau protein deposits. Symptoms in life include cognitive decline, memory loss, depression, impulsivity, and in severe cases dementia. It has been found in athletes in contact sports, military veterans, and others who experienced repeated head impacts.
Q: Can you get CTE from one concussion?
A: No. CTE is caused by repetitive head impacts, not a single event. It is the cumulative effect of repeated sub-concussive and concussive impacts over time. A player who has a single concussion and never plays again is not believed to be at significant CTE risk. The disease is specifically associated with careers of repeated exposure.
