New Delhi, Oct. 29 -- how much disease exists beyond the players whose brains scientists actually examine?

A Boston University-led study published Wednesday estimates that 74.5% of former NFL players who died between 2008 and 2023 had chronic traumatic encephalopathy, or CTE, pathology at death. The researchers reached that figure after adjusting for differences between brain donors and other deceased players, rather than treating donated brains as a representative sample.

The finding is a population estimate for a defined group of deceased players, not a diagnosis of three out of four living NFL retirees. It also does not mean that every player with the disease's brain changes experienced dementia or other symptoms. Those limits matter...