NFL players may face at least 25% CTE risk, study says

At least a quarter of National Football League players may develop chronic traumatic encephalopathy, according to a study published Tuesday in the British Medical Journal.

The study, led by Daniel Daneshvar of Harvard Medical School, looked at the brains of dead players who had played at least one NFL game in the mandatory plastic helmet era, which began in 1949.

Its main estimate came from players who died from 2016 to 2021, when brain donations were most frequent. Of 878 deaths in that period, 235 players had their brains donated and examined, and 215 were confirmed to have CTE.

Researchers said that meant the minimum rate was 24.5% if none of the players whose brains were not examined had CTE. The maximum estimate was 97.7%, with the true figure likely somewhere between those limits.

CTE is caused by repeated head impacts and can only be confirmed through a brain examination after death. Its symptoms include problems with thinking, memory loss, difficulty walking, emotional instability and suicidal thoughts.

The researchers also found a link between high-grade CTE and dementia before death among brain donors, based on medical notes and interviews with family members.

The authors said the study had limits, including that not all former NFL players who died during the study period were included and that some family members may have inaccurately recalled or overstated symptoms.

In a related editorial, Tobias Kurth of the University Medical Center Berlin and Richard Riley of the National Institute for Health and Care Research in Birmingham said no single study could fully define the rate of CTE among NFL players, but called the study one of the most informative estimates to date.