New Study Finds CTE Evidence in 93% of Donated NFL Player Brains

Among 338 NFL player brains studied from 2008–2021 across three brain banks (UNITE Brain Bank at Boston University, Mount Sinai, and UCSF ADRC), 315 were diagnosed with CTE, a rate of 93.2%.
The CBC report states that more than nine in ten donated brains showed evidence of CTE.
The study notes that 643 brains (of the 878 total) were not examined, implying the true prevalence of CTE among all former NFL players could be higher than the studied sample suggests.
Average age at death among the studied players was 66.5 years.
The study included players who died between 2008 and 2021 and who had played at least one NFL game after 1949, the first year plastic helmets were mandatory.
A new study found that at least 25% of former NFL players who died between 2016 and 2021 had CTE, a degenerative brain disease linked to repeated head impacts iHeart. Researchers examined 878 deceased players across three brain banks and discovered that roughly 9 in 10 donated brains showed signs of CTE. However, scientists caution that these numbers likely underestimate the true prevalence because many families never donated their loved ones' brains for study.
Among 338 NFL player brains analyzed from 2008 to 2021 across Boston University, Mount Sinai, and UCSF brain banks, 315 were diagnosed with CTE—a rate of 93.2% iHeart. This extremely high rate shocked researchers and underscores the widespread nature of brain damage in the sport. The average age of death among studied players was 66.5 years, suggesting long-term health consequences from their playing days.
The study examined only 235 of the 878 total player brains collected iHeart. The remaining 643 brains were not analyzed, creating a major blind spot. Researchers emphasize that donated brains came predominantly from families with concerns about disease during the player's lifetime. This selection bias means the real prevalence of CTE among all former NFL players is likely much lower than the 93% rate suggests.
The study found that bulk of head impacts causing CTE happened at the college and high school levels, not in the professional ranks iHeart. This discovery shifts focus beyond the NFL to younger athletes in youth leagues. It suggests that decades of cumulative impacts from multiple levels of play drive the disease. The findings raise urgent questions about protective measures needed at all levels of football.
One major limitation remains: doctors cannot diagnose CTE in living players iHeart. The disease can only be confirmed through brain autopsy. This reality creates a fundamental challenge for the NFL and researchers trying to protect current players. Advanced-stage CTE showed strong links to pre-death dementia symptoms, but scientists still cannot predict who will develop the disease. The NFL continues funding safety improvements and mental health resources despite the diagnostic limitation.
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