A new study has found that an estimated 74.5% of deceased former NFL players who died between 2008 and 2023 likely had chronic traumatic encephalopathy (CTE), a neurodegenerative brain disease associated with repeated head impacts. The research, published Wednesday in JAMA Network Open, analyzed medical records from 2,362 players, including 396 brain donors, and represents the most comprehensive effort to date to assess CTE prevalence in the league’s deceased alumni.
The study was conducted by researchers at Boston University, Mass General Brigham, and the Concussion & CTE Foundation. Nearly 94% of donated brains examined showed evidence of CTE, while the remaining players were assessed using National Death Index records. The findings suggest a strong correlation between professional football participation and CTE, though researchers caution that the study’s scope is limited to deceased players and does not apply to living athletes.
Key findings from the study include:
- 74.5% estimated prevalence of CTE among deceased NFL players from 2008–2023.
- 93.5% of donated brains (370 of 396) were diagnosed with CTE.
- Donors were more likely to have cognitive symptoms and died at a younger average age (67 years) compared to non-donors (75 years).
- 27.2% of players had a documented history of all-cause dementia during life, though the study did not establish a causal link between dementia and CTE.
Researchers emphasized that CTE can only be diagnosed posthumously, making it difficult to determine prevalence among living players. The study’s lead author, Julia Gallini, stated that the findings underscore the need for further research to develop in-life diagnostic tools and better understand the long-term health impacts on former athletes.
Background on CTE
CTE is a progressive brain disease linked to repeated head trauma, including concussions and subconcussive impacts. While initially identified in boxers, it has since been associated with football, hockey, rugby, and other contact sports. Symptoms, which may not appear until years after exposure, can include memory loss, mood swings, behavioral changes, and dementia. The disease is classified in four stages, with more severe cases associated with greater cognitive decline.
The study’s authors noted that many cases may have been early-stage at the time of death, meaning symptoms could have been absent or undetected. They also highlighted that the research does not address CTE prevalence in college, high school, or youth football players, leaving a gap in understanding the disease’s broader impact across all levels of the sport.
Reactions and Implications
Gallini and her team stressed the importance of expanding medical support for families of former players, given that over 20 million American men have played football at some level. The study’s findings have reignited discussions about player safety, rule changes, and long-term health protections in professional sports.
The NFL has faced years of scrutiny over its handling of concussions and brain injuries, including a $1 billion settlement in 2015 to compensate former players for neurological conditions. While the league has implemented rule changes to reduce head impacts, critics argue that more must be done to address the risks associated with the sport.
The researchers called for continued efforts to diagnose CTE during life, noting that such advancements could revolutionize how the disease is understood and managed. Until then, the study serves as a critical step toward quantifying the prevalence of CTE in one of the most high-profile groups of athletes affected by the condition.