The degenerative brain disease chronic traumatic encephalopathy (CTE) is likely much more common among former football players than previously thought, according to a new study from researchers at Mass General Brigham.
The study found that, among football players who played in at least one NFL game in their careers and who died between 2016 and 2021, roughly a quarter had CTE—and that prevalence is likely an underestimate, according to the study authors.
Harvard T.H. Chan School of Public Health’s Rachel Grashow, who was not involved in the study, said in an Aug. 25 Washington Post article that the study’s important contribution was how it attempted to estimate CTE’s prevalence among former football players.
CTE can only be diagnosed after death via a brain dissection. Typically, brains are donated for research by families or players because of symptoms experienced during a former player’s life—which means that estimating general CTE prevalence among football players based on this group can produce a skewed result.
The study tracked 878 former players, examined the brains of 235 of them, and found that 215—more than 91%—had CTE. To come up with a more accurate estimate of possible CTE prevalence, the researchers looked at publicly available personal, athletic, and cause of death data from all deceased NFL players from 2008 to 2021. Based on this larger dataset, the researchers estimated that, among players who died during the study period, the likely prevalence of CTE ranged between roughly 25% and nearly 98%.
In an Aug. 25 NPR article, she noted that conditions such as sleep apnea, high blood pressure, and low testosterone—all common among former NFL players and linked with previous head injuries—can lead to symptoms associated with CTE. Although CTE currently isn’t treatable, the other conditions are.
“Our concern is that the public and kitchen table conversations around CTE are creating hopelessness in living former NFL players,” she told NPR. “And this hopelessness may discourage them from reaching out to their doctors and getting treated for conditions, like sleep apnea, that are causing worrisome symptoms.” She said it’s important to encourage former players to tell doctors and loved ones about any concerning symptoms.
