Study Estimates That 75 Percent of NFL Players Who Died Between 2008 and 2023 Had CTE

A new study suggests that chronic traumatic encephalopathy (CTE) was present in the brains of roughly 75 percent of NFL players who died between 2008 and 2023.

CTE has been described as a neurodegenerative brain disease resulting from high-impact sports like football. Published in JAMA Network Open by researchers at Boston University, Mass General Brigham and the Concussion & CTE Foundation, the study proved 2,362 cases and “combined data from 396 players who donated their brain and the National Death Index records of the 1,966 deceased players who didn’t,” per ESPN.

The researchers cautioned that the estimate applies only to deceased NFL players and does not predict the prevalence of CTE in living NFL players. The study also doesn’t address prevalence among college or youth football players. Among other caveats were that the study doesn’t indicate what, if any, symptoms had manifested in the players that might have been related to CTE.

CTE is identified in stages ranging from I to IV based on severity. Researchers say symptoms often don’t manifest in the earliest stages.

Past research into CTE has drawn criticism for selection bias because of its reliance on brains donated by players who were more likely to have had symptoms while alive.

CTE can only be diagnosed after death, the study said.

“Many cases may have been early stage at the time of death and possibly symptom free,” it said.

Julia Gallini, the study’s lead author, said that the rate of 75 percent was “concerning” and called for more efforts “to support families, diagnose CTE during life, and treat CTE-related symptoms.”

“Even after accounting for differential brain donation, our findings suggest that the prevalence of CTE among deceased NFL players remains high,” the paper said.

The study did not probe the rates of CTE in high school or college football due to the lack of non-donors at that level.

NFL responded to the study in statement, saying that the organization “continuously strives to make the game of football safer, including by implementing strategies to reduce concussions and head impacts.”

“We encourage former players to utilize these resources to identify and seek treatment when they are concerned about their health,” it added.