Prevalence of CTE Among Former NFL Players and Its Implications

Chronic Traumatic Encephalopathy (CTE), a degenerative brain disease, has been linked to professional football for years. However, its prevalence among former players remained uncertain until recent findings by Mass General Brigham researchers, as published in The BMJ, revealed that at least 25% of NFL players who died between 2016 and 2021 had CTE.

CTE is caused by repeated head impacts and can only be diagnosed through brain dissection after death. Dr. Daniel Daneshvar, the study’s lead author, highlighted the previously unknown extent of CTE among players. The study analyzed players who had appeared in at least one NFL game and died within the specified period. It found that 25% had CTE, but the study suggested a potential maximum prevalence of up to 97% based on broader data and suspected cases.

Creating a comprehensive understanding of CTE prevalence involved creating a list of NFL players who died between 2016 and 2021, using data such as death certificates to form a denominator of 1,712 players. Although the NFL responded by emphasizing its commitment to player safety through measures to reduce concussions, the findings call attention to ongoing health concerns.

Some 215 deceased players, not involved in the brain bank study, had neurodegenerative diseases noted on death certificates, further complicating prevalence estimates.

The study also aimed to explore the link between dementia and CTE. It found that the advanced stage of CTE, Stage IV, had a strong correlation with dementia, diagnosed in over 90% of Stage IV cases. Conversely, less severe CTE stages did not consistently link to dementia, nor did brains without disease symptoms, where 40% still had dementia diagnoses.

Rachel Grashow from Harvard urged further research to address symptoms in living former players, encouraging discussions with doctors about symptoms that could result from treatable conditions linked to past head injuries, such as high blood pressure or sleep apnea.

Neurological surgeon Dr. Randall Chesnut praised the study but noted that the NFL’s actions to improve player safety in recent years, including altering gameplay to minimize dangerous situations and funding equipment research, may not be reflected due to the study’s focus on players from prior years. He also noted the average death age of 66 years among donors whose careers were before significant CTE recognition by the NFL in 2005.

Degenerative brain diseases are not exclusive to athletes. Research from Nature Medicine states that 42% of Americans over 55 have a lifetime risk of developing dementia.