Scientists Estimate Rate of CTE Among NFL Players

A new study puts a hard number on a question that's dogged the NFL: how many of its players die with CTE. Researchers from Mass General Brigham, writing in the British Medical Journal, estimate that at least 1 in 4 NFL players who died between 2016 and 2021 had the degenerative brain disease, which can only be confirmed with a brain study after death. Researchers examined the brains of 235 of the 878 players who died over the five-year period and found that at least 215 had CTE, per the New York Times.

They therefore calculated a minimum prevalence of 25% and a theoretical ceiling near 97%, with the truth likely "somewhere in the middle," lead author Dr. Daniel Daneshvar tells NPR. A 97% prevalence rate would assume all players had CTE apart from the 20 whose brains were free of the disease. The study also found that advanced CTE strongly tracked with dementia, but dementia was common even in players without CTE, underscoring the need for better diagnosis and treatment of other potential conditions. The NFL said it is continuing efforts to reduce head impacts and support player health.