At Least One in Four NFL Players May Have CTE

Helmet-to-helmet hits are now banned in the NFL. —George Gojkovich—Getty Images An alarming number of professional football players in the U.S. may someday have chronic traumatic encephalopathy (CTE) , the neurodegenerative disease associated with repeated concussions and sub-concussive hits to the head, a new study suggests.

The research, published in the BMJ , studied the brains of NFL players who died from 2016 to 2021 and found that one in four had CTE—a figure that is almost certainly an undercount, the researchers say.

Depending on how they crunched the numbers, the CTE incidence rose as high as 91%.

“The one in four figure is intentionally the most conservative estimate possible,” says lead author Dr.

Daniel Daneshvar, chair of the department of physical medicine and rehabilitation at Mass General Brigham and associate professor at Harvard Medical School.

“We know the true prevalence is higher than that.” It was in 1928 that pathologist Harrison Martland first described the condition now known as CTE in boxers experiencing what he called “punch drunk” syndrome.

It was not until 2002 that the disease was first diagnosed in an NFL player, when neuropathologist Bennet I.

Omalu examined the brain of Mike Webster, a former player for the Pittsburgh Steelers, and found the buildup of tau proteins around blood vessels, thinning of tissue, and overall brain atrophy that characterize the disease.

CTE is only firmly diagnosable by autopsy, but the range of symptoms that point to the disease—including memory loss, confusion, aggression, depression, apathy, tremors, and slurred speech—can be pronounced during a person’s life.

“Many of these former players had dementia,” says Daneshvar, “meaning their cognitive symptoms were severe enough to interfere with their ability to function independently.

These are not just microscopic changes that we happen to find when someone dies.

We are talking about a disease that can profoundly affect people’s ability to think, work, maintain relationships, and live independently.” What the research found In the new study, Daneshvar and his colleagues examined the brains of 235 former NFL players who had donated their brains to science. (A total of 878 players died in that 2016-2021 window.) Of the brains studied, 215 were found to have CTE—or 91%.

The researchers arrived at their much lower one-in-four figure by making the exceedingly cautious assumption that none of the remaining 643 brains would have shown signs of the disease—an assumption that Daneshvar believes would not stand up if the brains had been examined.

“Among the people who did not donate,” he says, “16% had dementia listed on their death certificate.