At least 25% of NFL players who died between 2016 and 2021 had CTE, study shows

A new study showed alarming results about just how many former football players have CTE.

At least one in four NFL players who died between 2016 and 2021 had the degenerative brain disease, a new study published Tuesday in the British Medical Journal revealed.

Of the 878 players who appeared in at least one NFL game and died in that six-year period, 235 had their brains donated to research with 215 of them found to have CTE, according to the study.

CTE is a degenerative brain disease that has been linked to concussions and other repeated head trauma common in contact sports like football. It can only be diagnosed after death, so the research is only possible if brains are donated by players or their families.

Dr. Daniel Daneshvar, the study's lead author, said the estimate of 25% is on the "low end." More than 90% of brains donated for the study had CTE, but Daneshvar said the true rate is likely "somewhere in the middle."

"Similarly, 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," he added.

Chronic traumatic encephalopathy, also known as CTE, can be prevented by lowering the risk of getting a concussion.

The study included research collected from Mass General Brigham, Boston University and the Concussion & CTE Foundation. Daneshvar is the chair of physical medicine and rehabilitation at Mass General Brigham and an associate professor at Harvard Medical School.

“The NFL continuously strives to make the game of football safer, including by implementing strategies to reduce concussions and head impacts,” the league said in a statement. “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.”

Daneshvar said that cumulative force of hits to the head are the biggest predictor of CTE. Eliminating hits during practices and limiting youth participation in tackle football will help mitigate risk, he argued.

“If the changes that have been implemented at the NFL level, including reducing the amount of contact in sports practices to less than one per week, were propagated at the collegiate, high school, and youth levels, athletes would be better off,” Daneshvar said.

“We know that nearly 70% of head impacts are occurring in practice. So without changing a single minute of game time at any of those levels, we can be substantially reducing the cumulative head impact burden that these individuals are experiencing throughout their lives.”

Medical Director for the NFL Players Association Dr. Thom A. Mayer has worked with thousands of athletes over his career– and raised three boys of his own. Here’s what he says about weighing the risks of youth sports with traumatic brain injury.