A study of nearly 20,000 former National Football League players provides the clearest population-level evidence to date linking professional football to neurodegenerative disease.
Researchers from 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.
The study analyzed health records from 19,824 NFL players who competed between 1960 and 2019. It is the largest retrospective cohort study of its kind. Researchers 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 researchers attributed to their lifelong commitment to fitness. However, the data showed 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 specific 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.
Career length also played a role. Players with five or more seasons had nearly double the risk of neurodegenerative death compared to those who played one to four seasons. This 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.
Researchers introduced a concept called the STARS effect, which stands for Selection Through Athletic Resilience Survivor. NFL players, as a group, are exceptionally healthy. They have lower rates of cancer, cardiovascular disease, and suicide compared to the general population. The same traits that enable someone to become a professional athlete, including physical resilience, discipline, and better access to medical care, also support longer overall survival.
Because NFL players would be expected to have lower rates of brain disease than the average person, the fact that they have dramatically elevated rates 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 highest among players who tend to have the fewest other health conditions.
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. A separate 2023 case series found CTE in 41 percent of deceased contact sport athletes under the age of 30. 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.
The findings do not mean every child who plays football or soccer is destined for cognitive complications. But they do mean that the number and severity of head impacts a young athlete accumulates over their playing career matters. Research shows that subconcussive hits, impacts that do not cause noticeable symptoms, may still affect brain health over time. The cumulative load is what researchers believe drives long-term risk.
Leagues and schools that have capped full-contact practice sessions have seen reductions in head impact exposure. Proper form in tackling and blocking reduces the frequency and severity of head impacts. A concussed brain is more vulnerable to a second impact before it has fully healed. Symptoms should fully resolve before an athlete returns to contact, with medical clearance from a qualified provider. Some sports and positions carry higher head impact exposure than others.
This study shows, with more data than ever before, 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. This study adds the strongest population-level data yet to that body of work.
