Professional football has long been associated with chronic traumatic encephalopathy (CTE), a degenerative brain disease. However, determining its true prevalence has been challenging. A recent study reveals that among ex-NFL players who passed away between 2016 and 2021, at least 25% had CTE.
For years, researchers have linked repeated head impacts to CTE, raising questions about how common the disease is among high-risk groups like professional football players. A team from Mass General Brigham published new research in The BMJ, aiming to establish a clearer understanding of CTE prevalence among deceased NFL players.
The study assessed former NFL players who appeared in at least one game and died from 2016 to 2021. According to Dr. Daniel Daneshvar, the study lead, while CTE can result from repeated brain injuries, its prevalence was unclear until now. Of the players studied, about 25% were found to have CTE at death.
Diagnosing CTE requires examining the brain post-mortem. Most research relies on brain donations, often from individuals who experienced symptoms like memory loss or mood swings suggestive of the disease. This has skewed understanding, particularly in athletes and veterans exposed to traumatic brain injuries.
The study used data from over 330 NFL players donated to the UNITE Brain Bank at Boston University. An overwhelming 93% had CTE. To gauge the sample’s representativeness, researchers compiled a list of players who appeared in NFL games since 1949 and cross-referenced it with CDC death records, identifying 1,712 players who passed in the study period. By focusing on those deceased between 2016 and 2021, they estimated CTE prevalence at a minimum of 25%.
However, the actual figure could be higher, the paper suggests. Outside of the brain bank sample, other diagnoses suggest higher CTE occurrence. An examination of death certificates revealed another 215 players’ documents listed a neurodegenerative disease. Excluding 20 players cleared of CTE, the potential prevalence might reach up to 97%. Daneshvar notes that the true rate likely falls between these figures.
The NFL has committed to making football safer, implementing strategies to reduce head impacts and support player welfare. They encourage former players to access resources for their health.
The study also explored the correlation between dementia and CTE. Since CTE can’t be diagnosed in living patients, the link between observed symptoms and posthumous diagnoses is unclear. Findings showed a strong connection between dementia and Stage IV CTE, with over 90% of Stage IV cases also identified with dementia based on medical histories. Yet, the link was weaker for lower CTE stages or samples without classic tau protein buildup. Approximately 40% of CTE-free brains were diagnosed with dementia.
Neuroepidemiologist Rachel Grashow from Harvard’s T.H. Chan School of Public Health emphasized the importance of addressing treatable conditions like sleep apnea and high blood pressure, which could cause similar symptoms to CTE. For former NFL players experiencing symptoms, she advocates seeking medical advice.
Dr. Randall Chesnut, a neurological surgeon at the University of Washington, described the study as significant and thorough. He noted the average age of deceased players—around 66—indicates their careers occurred before CTE’s better understanding and the NFL’s improved safety measures. Changes in safety protocols since then may impact future CTE prevalence findings.
Degenerative brain diseases aren’t exclusive to head injury sufferers. A study in Nature Medicine reported that, among Americans over 55, there’s a 42% lifetime risk of developing any dementia form.