Study Estimates 74.5% of Deceased Former NFL Players Had CTE – MedicalResearch.com

Julia Gallini
Julia Gallini
PhD Candidate, Biostatistics
Boston University
Because chronic traumatic encephalopathy (CTE) can currently be diagnosed only after death, estimates of how common it is depend on brain bank data, and brain donors are not a random sample of players.

MedicalResearch.com: What is the background for this study? What are the main findings?
Response: More than 20 million American men alive today have played football. It is crucial to learn how many may have CTE to ensure the medical community is prepared to support families fighting suspected CTE. Because right now CTE can only be diagnosed after death, we have to estimate the prevalence of CTE using brain bank data. We studied deceased former NFL players to understand the risk in the population that has played football the longest. 94% of brain donors in this population had CTE present in the brain. This number is an overestimate for what the prevalence of CTE is in the entire deceased former NFL player population because of selection bias: players with cognitive symptoms while they were alive are more likely to have their brain donated than players without cognitive symptoms. To account for this selection bias, we looked at the differences between those who had their brain donated and those who didn’t, including whether or not they died from a dementia-related cause, milder cognitive symptoms, age of death, position, years of play, and other factors. We estimated that those with cognitive symptoms were about five times more likely to have their brain donated than those without cognitive symptoms. We used this estimate to scale down the 94% CTE prevalence in our brain bank to a 74.5% CTE prevalence among all deceased former NFL players.
MedicalResearch.com: How much of CTE may be attributable to head injuries sustained before National Football League play (i.e., in high school, college, etc.) where head protection may not be as thorough?
Response: It is difficult to say how much CTE is attributable to injuries sustained at lower levels of play since we cannot currently diagnose CTE in life. The biggest risk factor for CTE is the number of hits to the head over the course of a player’s career. There exist cases of CTE in individuals who have only ever played up to college football and even high school football. Restrictions on hitting in practices in college and high school, as have been implemented in the NFL, would greatly reduce the amount of exposure sustained at these levels and dramatically lower CTE risk.
MedicalResearch.com: What should readers take away from your report?
Response: While this number is concerning, it’s not a cause for panic. We really view this as a call to action to support the medical needs of NFL players, make the game safer for future generations, and increase research efforts towards finding a cure.
Not everyone who has CTE present in the brain will experience symptoms. Among those who develop symptoms, not everyone has them early in life, and many continue to thrive well into the later decades of their lives. We encourage former football players with concerns to access help resources at concussionandcte.org/helpline.
MedicalResearch.com: What recommendations do you have for future research as a result of this study?
Response: We are making significant progress towards diagnosing CTE in living patients, which will allow us to start clinical trials to find treatments and ultimately a cure. We invite former players to enroll in studies aimed at diagnosing and treating CTE during life. We hope this informs conversations on CTE prevention. This disease is preventable. Repeated head impacts are the only known risk factor, so we need to limit the number of times players are hit in the head. Future research should also investigate the prevalence of CTE at lower levels of play to better understand the medical needs of this community.
MedicalResearch.com: Is there anything else you would like to add? Any disclosures?
Response: This study would not have been possible without the NFL player community and their families. We cannot thank them enough for their generosity.
For parents wondering whether or not their child should play football, we highly recommend avoiding tackle football at least until high school to limit exposure to head impacts. Flag football and other team sports are an excellent alternative.
I have nothing to disclose.
Citation: Gallini J, Alosco ML, Abdolmohammadi B, et al. Bias-Adjusted Prevalence of Chronic Traumatic Encephalopathy Among Deceased National Football League Players. JAMA Netw Open. 2026;9(10):e2640884. doi:10.1001/jamanetworkopen.2026.40884
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Last Updated on October 29, 2026 by Marie Benz MD FAAD
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The information on MedicalResearch.com is provided for educational purposes only, and is in no way intended to diagnose, cure, or treat any medical or other condition. Some links are sponsored. Products, services and providers are not warranted or endorsed. Always seek the advice of your physician or other qualified health personnel and ask your doctor any questions you may have regarding a medical condition. In addition to all other limitations and disclaimers in this agreement, MedicalResearch.com, Eminent Domains Inc., service providers and third party providers disclaim any liability or loss in connection with the content provided on this website.
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