A new study analyzing health records of nearly 20,000 former NFL players has produced what researchers call the clearest population-level evidence linking professional football to neurodegenerative disease. The findings have implications beyond professional sports.
The study, conducted by researchers at Mass General Brigham, Boston University, and the Concussion & CTE Foundation, found that NFL players are nearly four times more likely to die from neurodegenerative disease than the general population. This includes dementia and Parkinson’s disease, two conditions that affect tens of millions of people worldwide.
Researchers analyzed health records from 19,824 NFL players who competed between 1960 and 2019. They compared player mortality rates across every official cause of death against national rates for the general population.
NFL players had lower overall mortality than the general population, which was unsurprising due to their lifelong commitment to fitness. But the data revealed NFL players were nearly four times more likely to die from neurodegenerative disease. Even after accounting for other known risk factors, neurodegenerative mortality was still three times higher for players compared to the general population.
The study broke down the findings by disease. NFL players died from dementia at 3.8 times the rate of the general population. They died from Parkinson’s disease at 3.88 times the rate of the general population. Players who died before age 60 had more than 12 times the neurodegenerative death rate of the general population. Players with five or more seasons had nearly double the risk of neurodegenerative death compared to those who played one to four seasons.
That last finding points to a dose-response relationship, meaning the more football a player plays, the higher the risk. This pattern mirrors what researchers have found in studies of CTE, a degenerative brain disease linked to repeated head trauma.
NFL players, as a group, are exceptionally healthy. They have lower rates of cancer, cardiovascular disease, and suicide compared to the general population. The study introduces a concept called the STARS effect, which stands for Selection Through Athletic Resilience Survivor. The same traits that enable someone to become a professional athlete, including physical resilience, discipline, lower rates of early illness, and better access to medical care, also tend to support longer overall survival.
In other words, NFL players would be expected to have lower rates of brain disease than the average person, not higher ones. The fact that they have dramatically elevated rates instead suggests the true relationship between playing football and neurodegenerative disease may be even stronger than the fourfold increase implies.
The study noted that neurodegenerative deaths were actually highest among players who tend to have the fewest other health conditions. Linemen, who generally have higher body weight and related health issues like sleep apnea, had half the dementia mortality compared to non-linemen. This further emphasizes that the brain disease risk seen in football players is not explained by general poor health.
Researchers have identified CTE in athletes across a wide range of sports, including boxing, soccer, rugby, ice hockey, and wrestling. Over 97 percent of CTE cases have been found in individuals with known exposure to repeated head impacts, and there is a dose-response relationship between CTE and years of football play.
A separate 2023 case series found CTE in 41 percent of deceased contact sport athletes under the age of 30, the majority of whom played American football, ice hockey, soccer, rugby, and wrestling. A 2025 study found that repeated head trauma causes brain cell loss and inflammation in young athletes before the hallmark changes of CTE even appear, suggesting the injury process starts well before any diagnosis is possible.
Research shows that subconcussive hits, impacts that don’t cause noticeable symptoms, may still affect brain health over time. The cumulative load is what researchers believe drives long-term risk, not any single blow. Leagues and schools that have capped full-contact practice sessions have seen reductions in head impact exposure.
This study shows that playing in the NFL significantly raises the risk of dying from dementia or Parkinson’s disease. The more seasons a player competes, the higher that risk climbs. The evidence connecting contact sports to brain disease has been building for years, across multiple sports and multiple countries.
