At least one in four former NFL players who died between 2016 and 2021 may have had chronic traumatic encephalopathy (CTE), according to a new study published in The BMJ. Researchers from Mass General Brigham, Boston University, and the Concussion & CTE Foundation analyzed 1,712 former NFL players who died between 2008 and 2021, examining 338 donated brains.
Among these donated brains, 315, or 93.2%, showed evidence of CTE, a degenerative brain disorder linked to repeated head injuries. Based on these findings, the study authors estimated that the minimum prevalence of CTE among all former NFL players who died between 2016 and 2021 was 24.5%.
The study also investigated the link between severe CTE and cognitive decline. Nearly 60% of the brain donors had dementia, and 90.4% of those with the most severe form of CTE (stage IV) also had dementia. After adjusting for differences between brain donors and non-donors, stage IV CTE was associated with a 44% higher risk of dementia.
Researchers pointed out that many cases of dementia were not recorded on death certificates, suggesting that the impact of neurodegenerative disease among former players might be underestimated. The study's lead author, Dr. Daniel Daneshvar, stated that the high prevalence of CTE in former NFL players is a "wake-up call for the NFL and scientific communities," contrasting it with CTE affecting less than 1% of the general population based on community brain bank studies.
The researchers recommended that future studies focus on more recent athletes and that prevention efforts should prioritize reducing repetitive head impacts, not solely focusing on concussions. In response, the NFL stated to ESPN 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."