1 in 4 former NFL players may have CTE, new study says

Researchers analyzed 1,712 former players who died between 2008 and 2021.

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 Monday 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 and found that 338 brains were donated for examination.

Among those donors, 315 of the, or 93.2%, had evidence of CTE, a degenerative brain disorder that can be caused by repeated head injuries.

Based on those findings, the 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 examined whether more severe disease was linked to cognitive decline. Among brain donors, nearly 60% had dementia and 90.4% of those with the most severe form of CTE (stage IV) had dementia.

After accounting for differences between donors and non-donors, stage IV CTE was associated with a 44% higher risk of dementia.

Researchers noted that many cases of dementia were not captured on death certificates, suggesting the burden of neurodegenerative disease among former players may be underestimated.

"Community brain bank studies have shown that CTE affects less than 1% of the general population. To find that somewhere between 24.5% and 97.7% of NFL players from that time period had this progressive brain disease is a wake-up call for the NFL and scientific communities," the study's lead author Dr. Daniel Daneshvar said in a statement.

The researchers said that future studies should look at athletes who played more recently, and that prevention efforts need to focus on reducing repetitive head impacts that lead to CTE risk, not just concussions.

In a statement to ESPN , the NFL said it "continuously strives to make the game of football safer, including by implementing strategies to reduce concussions and head impacts."

The statement went on, "The NFL 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."