New Study: 75% of Deceased NFL Players Likely Had CTE

Approximately 75 percent of National Football League players who died between 2008 and 2023 likely suffered from chronic traumatic encephalopathy, a new study found. Published Wednesday in JAMA Network Open, the research offers a more precise estimate of the disease's prevalence than previous data, which had been skewed by the tendency of symptomatic players to donate their brains for analysis.

The investigation builds on a preliminary report from late August that suggested a wide range of 25 to 98 percent for CTE rates. Julia Gallini, the lead author and a PhD candidate at Boston University School of Public Health, stated that while the new figure does not predict that three-quarters of current players will develop the condition, the magnitude of the risk warrants concern for active athletes.

Researchers analyzed data from 387 former players who donated their brains, finding that 362, or about 94 percent, had CTE. To account for the fact that players with symptoms were five times more likely to donate their brains, the team examined death certificates for all 2,362 NFL players who died during the 15-year study period. They factored in age, position, years played, and cognitive symptoms to estimate the true prevalence across the entire deceased cohort.

The NFL responded by referencing a statement issued after the August report, noting that the league strives to make the game safer through strategies to reduce concussions and head impacts. The league’s spokesperson added that it remains committed to providing players with resources to enhance physical and mental wellbeing. Chris Nowinski, co-founder of the Concussion & CTE Foundation and a study author, said the new data addresses longstanding questions about selection bias in brain banks.

The study highlights that CTE is a progressive neurological disease likely caused by repeated head injuries. A 2019 study found that the odds of developing CTE double for every 2.6 years of football played. While the NFL has required most players to wear Guardian caps or specific helmets during contact practices since 2022, Nowinski argued that these measures may not fully protect against CTE.

Authors of the new study advise parents to keep children out of tackle football before high school, noting that exposure to head impacts often begins at the youth and high school levels. Dr. Daniel Daneshvar, chair of physical medicine and rehabilitation at Mass General Brigham, pointed out that many affected players had significant exposure well before their professional careers. Flag football has seen a surge in participation among children ages 6 to 12, overtaking tackle football in recent years.

The research team is currently working on identifying biomarkers that could allow for diagnosis in living patients. Gallini noted that former NFL players are about four times more likely to develop dementia compared to the general population. She said, “No other environmental or occupational exposure ever studied, to our knowledge, is known to affect dementia risk by that much.”