Study finds CTE prevalence in ex-NFL players higher than previously shown

A study published in the British Medical Journal found that as many as 97.7% of former NFL players who died between 2016 and 2021 could have had brain disease related to repeated blows to the head. Researchers analysed 878 former players who died in that six-year period.

The number of brains donated to research by former NFL players has tripled since 2017. Of the 878 former players who died between 2016 and 2021, 235 had donated their brains to research and 215 of those donors were found to have chronic traumatic encephalopathy (CTE). CTE can only be diagnosed after death, and the study also reported that dementia was common among the brain donors.

"We and others have shown that in NFL players, specifically, there is about a four times higher rate of death from neurodegenerative disease than the general population," said the report's lead author Daniel Daneshvar, an associate professor at Harvard Medical School. "These findings indicate that NFL players have a higher prevalence of CTE at death than has been previously shown in multiple community based studies."

The researchers calculated a "conservative minimum" CTE prevalence of 24.5% among those who died in the six-year period and a "maximum" estimate of 97.7%. The paper calls attention to the range between those estimates without altering the underlying diagnostic counts of donated brains.

"The bulk of the head impacts that these former NFL players experienced didn't occur at the NFL level," Danshvar said. "They occurred at the collegiate level and at the high school level and in many cases the youth level. And all of those cumulative hits to the head added up to result in an increased risk."

An NFL spokesperson said: "The NFL continuously strives to make the game of football safer, including by implementing strategies to reduce concussions and head impacts. "The NFL remains committed to ensuring that the NFL community has access to a robust - and expanding - set of resources to enhance their physical and mental well being. "We encourage former players to utilise these resources to identify and seek treatment when they are concerned about their health."

The study noted that CTE among American football players has been a growing issue in recent years. A 2011 Collective Bargaining Agreement for the NFL limited the number of contact practices, and in 2016 the NFL agreed a $1bn (£700m) settlement with more than 5,000 former players.

The researchers have urged the NFL to take prevention measures to reduce repetitive head impacts across all levels of the sport.