A new study analyzing nearly 20,000 National Football League players has found that professional football players are nearly four times more likely to die from brain diseases such as dementia and Parkinson’s disease compared to the general population. Researchers from Mass General Brigham, Boston University, and the Concussion & CTE Foundation conducted the study, which they describe as the clearest population-level evidence to date linking professional football to neurodegenerative disease.
The study examined 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 for every official cause of death against national rates for the general population.
While NFL players had lower overall mortality than the general population, likely due to their lifelong fitness, the data showed they were nearly four times more likely to die from neurodegenerative disease. After accounting for other known risk factors, the rate was still three times higher for players.
The findings were broken down 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. Those with five or more seasons had nearly double the risk compared to those who played one to four seasons.
This 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 chronic traumatic encephalopathy, a degenerative brain disease linked to repeated head trauma.
The study introduced a concept called the STARS effect, which stands for Selection Through Athletic Resilience Survivor. NFL players are exceptionally healthy as a group, with lower rates of cancer, cardiovascular disease, and suicide. The same traits that enable someone to become a professional athlete also support longer overall survival. Because 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 may be even stronger than the fourfold increase implies.
Neurodegenerative deaths were 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 is not explained by general poor health.
The NFL study is the largest of its kind, but it is not the first evidence linking contact sports to brain diseases. Researchers have identified CTE in athletes across a wide range of sports, including boxing, soccer, rugby, ice hockey, and wrestling. Over 97% of CTE cases have been found in individuals with known exposure to repeated head impacts.
A separate 2023 case series found CTE in 41% of deceased contact sport athletes under the age of 30. The majority 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.
