Landmark study finds three in four NFL players die with CTE

Scientific American · Jackie Flynn Mogensen · 2026-10-28 15:00 UTC

The staggering new estimate is based on an analysis of thousands of former players’ medical records

American football can be brutal. Scientists have long known that the hits, tackles and other collisions that are central to the sport come with health risks, but what these impacts do to the brain has been less clear. What we do know is that many footballers have died with brains that have shown evidence of chronic traumatic encephalopathy (CTE), a disease associated with symptoms such as mood swings and dementia. But because a diagnosis requires that investigators look for damage in a person’s brain after they die, it’s unclear just how common CTE is among current or former athletes.

But now, in a study published in JAMA Network Open, an analysis of medical records from thousands of deceased former NFL players—including hundreds who donated their brains to science—estimates that about 75 percent of these players likely died with CTE.

“No other environmental or occupational exposure ever studied is known to have increased dementia risk at death by that amount,” says Yorghos Tripodis, senior author of the paper and a professor of biostatistics at Boston University.

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