NFL players die from neurodegenerative diseases such as dementia and Parkinson’s at four times the rate of the general population, according to a major study released Wednesday by researchers at Mass General Brigham, Boston University, and the Concussion and CTE Foundation, representing the most comprehensive population-level evidence yet linking professional football careers to elevated brain disease mortality.
The study examined 19,824 athletes who played in the NFL between 1960 and 2019, including the 1,994 who have died, making it the largest retrospective cohort study of this kind conducted to date. The researchers described the findings as tragic but not surprising given the accumulation of evidence in recent years, and they called for urgent attention to reducing the total head impact exposure that players experience across their careers.
The most alarming finding involved younger players
While the overall elevated rate was significant, the findings for players who died before the age of 60 were substantially more severe. That group had a neurodegenerative death rate 12 times higher than the general population, a figure that the researchers said reflected the particular danger that repeated head impacts pose to players whose deaths come before the natural emergence of age-related dementia in the broader population.
The researchers obtained death certificates from the Centers for Disease Control and Prevention for the players who died and found a consistent pattern across the decades studied. Despite concerns that the data might show improvement due to rule changes and equipment advances over time, the rates of neurodegenerative death remained consistent across eras. Researchers cautioned against interpreting that stability as proof that the game has not become safer, however, noting that competing factors including longer amateur careers before reaching the professional level and athletes becoming stronger and faster over time may be offsetting any protective benefits from rule and equipment changes.
The surprising finding about skill-position players
One result the researchers did not anticipate was the gap between skill-position players and linemen. Skill-position players, typically those who carry or catch the ball and face high-speed collisions from multiple directions during games, had neurodegenerative disease listed as a cause of death at nearly twice the rate of offensive and defensive linemen. The researchers suggested this may be related to greater cumulative force exposure, since skill-position players tend to experience more high-speed, high-impact collisions over a career than linemen, whose impacts are generally lower velocity even if more frequent.
This finding complicates the intuitive assumption that the largest players face the greatest long-term brain health risk. The research suggests that the nature and velocity of impacts may matter as much or more than their frequency.
Why CTE is the most likely explanation
NFL players are generally healthier than the broader population in ways that would be expected to reduce their rates of most diseases. The study confirmed this, finding that players died from cancer, cardiovascular disease, and suicide at lower rates than national averages. That finding matters because it eliminates the most common alternative explanations for elevated dementia rates in NFL players, including high body weight, poor metabolic health, sleep apnea, and cardiovascular problems that can independently increase dementia risk.
Because those factors are less prevalent in NFL players than in the general population, and because neurodegenerative deaths are still dramatically elevated, the researchers concluded that the most likely explanation is chronic traumatic encephalopathy, the progressive brain disease caused by repeated head impacts. The study does not prove CTE causes neurodegenerative death in every case, but it closes off the alternative explanations that have been used to question that connection.
The most effective intervention available, researchers said, is reducing total head impact exposure, beginning with the age at which players start contact sports and extending through how teams structure practice.
