Study: At least 25% of NFL players in sample had CTE

At least one in four NFL players who died between 2016 and 2021 had the degenerative brain disease known as CTE, a new study has revealed.

The study, published Tuesday by the British Medical Journal, focused on how common chronic traumatic encephalopathy might be among NFL players. What it found is that of the 878 players who appeared in at least one NFL game and died in that six-year period, at least 25% had CTE.

CTE can be diagnosed only after death, so most research has depended on brains donated by players or their families. This study drew on samples donated between 2008 and 2021, 93% of which had been diagnosed with CTE, then narrowed the sample based on when donations were highest and factored in demographic data and information from death certificates.

The estimate of 25% is on the "low end," said Dr. Daniel Daneshvar, the study's lead author. The study found that the maximum possible prevalence of CTE was around 97%, but the true rate "is somewhere in the middle," Daneshvar said.