An estimated three-quarters of NFL players who died in a 16-year period had the devastating neurogenerative disease called CTE.
Back in 2017, researchers reported that an estimated 99 percent of former NFL players developed CTE, or chronic traumatic encephalopathy, from an analysis of donated brains. But the families who provided the donations may have done so because their football-playing relatives had symptoms related to CTE, which could skew the results. A new study, which accounts for this potential bias, estimates that nearly 75 percent of former NFL players have CTE at death. It’s the first population-level estimate for NFL players, researchers report October 28 in JAMA Network Open.
The development of CTE is linked to repeated blows to the head over time. The disease can occur in people who play contact sports, experience intimate partner violence or engage in military combat. A study of American football players suggests that the longer the duration of repeated head trauma, the higher the risk of CTE and the more severe the condition. During life, people who are later diagnosed with CTE can experience symptoms including memory issues, difficulty concentrating, depression and poor impulse control.
A brain protein called tau, which usually helps nerve cells communicate and performs other jobs, goes awry in CTE. Brains with the disease are snarled with irregular, damaging clumps of the protein. The condition is diagnosed after death, during an autopsy, and has been identified most frequently among American football players.
The new study, by a Boston University research team, included all previous NFL players who passed away from January 2008 through December 2023. The more than 2,300 players included almost 400 with samples in the university’s UNITE Brain Bank, with the remainder identified from records in the U.S. National Death Index. The research team determined that families of NFL players who had CTE-related symptoms in life were five times more likely to donate their relative’s brain than families whose relative did not experience symptoms. Taking that into consideration, the team landed on a population-level CTE estimate for NFL players of 74.5 percent.
The research team notes that determining the true prevalence of CTE is important to understanding the public health impact of the disease.