Three in four former NFL players had CTE when they died, according to a major study

A study published on Wednesday, October 28, in a journal of the JAMA group estimates that three in four former NFL players had CTE when they died.

The work was done by researchers at Boston University.

What CTE is

Chronic traumatic encephalopathy (CTE) is a disease that damages the brain little by little. It is linked to repeated blows to the head.

Today it can only be confirmed after death, by studying the brain. And not everyone who has it shows symptoms.

Among the donated brains, 93.5% had CTE; the final estimate drops to 74.5% after correcting for that bias.

How they calculated it

The scientists analyzed 2,362 former players who died between 2008 and 2023. Some had donated their brains to science and the rest had not.

The problem is that families who noticed memory or behavior problems donate more: according to the authors, about five times more. So they corrected for that effect.

The result: 74.5% had CTE at death. Even with the most cautious calculations, the figure stays at 60% or more. They also estimate that 27.2% had dementia during their lifetime.

What it does not say

The study covers players who have already died, many from an era before today's concussion protocols. It cannot predict how many living or active players have the disease.

In August, part of the same team had published another study with a very wide range, between 25% and 98%. This new estimate aims to be more precise.

The responses

The players' union said the research is key to understanding football's long-term effects. The NFL said it works to make the game safer, with fewer concussions and head impacts.