Key facts
- Study examined 235 of 878 former NFL players who died 2016-2021; 215 brains showed CTE, equating to a 24.5% minimum rate
- Researchers calculated CTE prevalence among sampled players at 24.5% to 97.7%, with true rate likely in the middle range
- 61.3% of brain donors with CTE met clinical criteria for dementia; rates ranged from 29.2% (Stage I) to 90.4% (Stage IV)
- CTE can only be definitively diagnosed after death; symptoms include memory loss, mood changes, cognitive difficulties, and dementia
- NFLPA sent email to all players and agents emphasizing treatment availability and importance of early medical evaluation
The study and its findings
On August 25, researchers from Mass General Brigham, Boston University, and the Concussion + CTE Foundation published a study in The BMJ examining the prevalence of chronic traumatic encephalopathy (CTE) among former NFL players. The study analyzed brain samples from 235 of 878 former NFL players who died between 2016 and 2021. Of the 235 donated brains examined, 215 showed evidence of CTE. This equates to a minimum prevalence rate of 24.5%.
Dr. Daniel Daneshvar, the study’s lead author and chair of physical Medicine and Rehabilitation at Mass General Brigham, characterized the findings as significant. He noted that CTE affects less than 1% of the general population. The researchers calculated that the true prevalence of CTE among the sampled NFL players likely falls somewhere between the 24.5% minimum and a maximum possible rate of 97.7%.
Dementia and severity patterns
The study also examined connections between CTE and dementia diagnosis. Among brain donors with CTE, 61.3% met clinical criteria for dementia. The prevalence of dementia increased with CTE severity: Stage I CTE had a 29.2% dementia rate, Stage II had 22.5%, Stage III had 56.5%, and Stage IV had 90.4%.
According to Daneshvar, NFL players experience about four times the rate of death from neurodegenerative disease compared to the general population. He emphasized that repeated traumatic brain injuries—sustained not only at the professional level but also during college, high school, and youth football—accumulate over time to elevate the risk of neurodegenerative disease.
NFLPA response and resources
The NFL Players Association responded swiftly to the study, sending an email on Tuesday to all players and player agents. The message acknowledged that the findings are “a sobering reminder that football carries serious risks that can have lasting consequences for players and their families.” The NFLPA stressed that while many symptoms associated with CTE—including memory challenges, mood changes, depression, anxiety, sleep disturbances, and cognitive difficulties—can also stem from other treatable medical or neurological conditions, thorough medical evaluation remains crucial.
Citing Daneshvar’s expertise, the NFLPA noted that “many of the symptoms associated with CTE are treatable with the right care” and that players who receive care from doctors specializing in neurodegenerative disease have shown improvements. The union emphasized that early intervention matters and urged players to pay attention to their cognitive, neurological, and overall health.
The NFLPA highlighted its investments in brain health research and care, including partnerships with the American Brain Foundation and the Football Players Health Study at Harvard University. The union also pointed to resources available through its Former Players Department, the Professional Athletes Foundation, and the Trust, which offer comprehensive evaluations, wellness support, care navigation, and treatment resources.
NFL and institutional responses
The NFL stated that it “continuously strives to make the game of football safer, including by implementing strategies to reduce concussions and head impacts” and remains “committed to ensuring that the NFL community has access to a robust—and expanding—set of resources to enhance their physical and mental well being.” The league encouraged former players to utilize available resources to identify and seek treatment for health concerns.
The study’s findings come in the context of cumulative safety efforts across the sport. The NFL’s 2011 collective bargaining agreement limited contact practices during the season, and the Ivy League banned full-contact tackling during practices in 2016. The U.S. Supreme Court cleared the way for the NFL’s settlement of concussion-related lawsuits with retired players in 2016.
Background on CTE
CTE is a degenerative brain disease associated with repeated blows to the head, including concussions. It can only be definitively diagnosed after death through brain examination. Symptoms include memory loss, attention difficulties, mood disorders, dementia, and headaches. High-profile NFL players including Junior Seau, Dave Duerson, and Aaron Hernandez were found to have had CTE upon post-mortem analysis.
Sources
Featured photo: Tony Webster via Wikimedia Commons (CC BY 2.0)