A new study found that National Football League players are four times likelier to die due to neurodegenerative disease than the general population. The cohort study of nearly 20,000 NFL players revealed that while players had lower mortality on average compared to national rates, they were four times more likely to experience neurodegenerative mortality. Results of the research from Mass General Brigham, Boston University, and the Concussion & CTE Foundation are published in eClinicalMedicine.

“This is the clearest population-level evidence we have ever had that NFL players are dying due to neurodegenerative disease at real and measurably higher rates,” said co-senior author Daniel Daneshvar, Harvard Medical School associate professor and chair of the Department of Physical Medicine and Rehabilitation at Spaulding Rehabilitation Hospital. “This study demonstrates that, when looking at athletes who have played in an NFL game, including nearly 20,000 players, across every official cause of death, the result is the same: NFL players are dying of dementia and Parkinson’s disease three to four times more often than they should.”

Neurodegenerative diseases, like dementia, ALS, or Parkinson’s, affect tens of millions of people worldwide. Typically, age is the biggest risk factor for developing neurodegenerative diseases, but studies have revealed individuals with repetitive head impact exposure — like pro football players — also have higher incidence of the diseases. In the biggest retrospective cohort study to date, researchers looked at health records of 19,824 NFL players who competed between 1960 and 2019 to determine exactly how much higher.

They found that players had lower all-cause mortality but nearly four times higher neurodegenerative mortality, including all-cause dementia (3.8 times higher) and Parkinson’s (3.88 times higher). When accounting for other known risk factors, neurodegenerative mortality was still three times higher for players compared to the general population.

The increase was even more significant for younger NFL players. Those who died before age 60 had more than 12-fold increased rates of neurodegenerative death compared to the general population. Players with longer careers (five seasons or more) had nearly double the risk of neurodegenerative death compared to those with shorter careers (one to four seasons), reinforcing a dose-response relationship between years of play and brain disease risk identified in studies of chronic traumatic encephalopathy (CTE).

“A fourfold increase in dementia rates from a presumed environmental cause is immense — and brain bank studies indicate that CTE is the primary explanation,” said study co-senior author Jesse Mez, associate director of the Boston University Alzheimer’s Disease Research Center and co-director of clinical research at the BU CTE Center. “To put that in perspective, heavy lead exposure, which was banned from paint and gasoline in the U.S. due to its neurological and cardiovascular consequences, leads to a two to three times greater rate of dementia and a 1.5 times greater rate of cardiovascular death.”

The study shows that NFL players had significantly lower overall mortality than the general population despite their dramatically elevated neurodegenerative disease rates. NFL players were less likely to die from cancer, cardiovascular disease, and suicide — underscoring that this is a population that is generally healthier yet still dying of brain disease at higher rates.

The study also introduces a new concept called the Selection Through Athletic Resilience Survivor (STARS) effect to explain why former NFL players tend to live longer overall. The STARS effect suggests that the same genetic, environmental, medical, and behavioral characteristics that enable individuals to become professional athletes — such as exceptional physical and cognitive performance, resilience, self-discipline, and lower rates of smoking and serious early illnesses and injuries — also contribute to longer overall survival. Higher educational attainment and better access to medical care may further offset the effects of other health conditions later in life. Those advantages make the elevated rates of neurodegenerative disease even more striking because NFL players would otherwise be expected to have lower rates of brain disease than the general population due to these health advantages.

Taken together, the STARS effect suggests that the fourfold increase in neurodegenerative disease found in NFL players may actually under-represent the true relationship between playing in the NFL and neurodegenerative disease, as NFL players would otherwise be expected to have lower rates of brain disease in the same way that they have lower rates of cancer and cardiovascular disease. In fact, neurodegenerative disease deaths were highest in athletes who tend to have the fewest comorbidities; linemen, who are generally heavier, with higher body-mass indices and related comorbidities including sleep apnea, had half the dementia mortality of non-linemen.

Former NFL players who are concerned about their brain health or neurodegenerative disease risk are encouraged to seek evaluation from clinicians specializing in neurodegenerative disease. Many conditions can cause symptoms that resemble neurodegenerative disease, and many of these conditions are treatable. Even when long-term risk cannot be eliminated, identifying and managing modifiable risk factors can help support overall brain health and quality of life. Players seeking guidance, specialist referrals, or support managing health concerns are encouraged to use available resources, including The Trust Powered by the NFL Players Association (NFLPA), the NFLPA’s Professional Athletes Foundation, and the Concussion & CTE Foundation HelpLine. 

Funding for the research in this story came from the National Institute of Neurological Disorders and Stroke, the National Institute on Aging, and the Maloney/Carpenter Trauma-Related Neurodegenerative Disease Research Fund.