The most disturbing evidence in the concussion debate emerged not from game footage but from autopsy rooms. On September 30, 2014, Boston University researchers reported that 76 of 79 examined former NFL players’ brains showed signs of chronic traumatic encephalopathy, a degenerative disease associated with repetitive brain trauma and abnormal tau-protein accumulation. By January 2017, the reported total had risen to 90 of 94, and a 2017 Journal of the American Medical Association study found CTE pathology in 110 of 111 donated former NFL brains. Later research reported that the odds of CTE approximately doubled for every 2.6 additional years of football participation, with roughly a tenfold increase over nine additional years. The disease has been associated with memory loss, depression, anxiety, headaches, sleep disturbance, impaired judgment, and other debilitating post-career symptoms, and the suicides of former players helped bring the issue into public view. The figures require caution because brain donations are not a random sample of all football players and are heavily influenced by families’ concerns about neurological illness. Even with that limitation, the findings transformed CTE from a disputed possibility into a central legal, medical, and labor issue. More than 2,000 former players ultimately pursued claims against the NFL, alleging that the league concealed or minimized evidence that repeated head impacts could cause permanent brain damage, dementia, and Alzheimer’s-like disease.
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