# CTE prevalence and safety responses in NFL > Live situation record from CLSTR: https://clstr.news/situations/cte-prevalence-in-former-nfl-players > Updated: 2026-09-09T20:34:00.000Z. Sources: 17. Developments: 4. Research published in the British Medical Journal (BMJ) has identified a high prevalence of chronic traumatic encephalopathy (CTE) among former NFL players. An analysis of brains donated by players who died between 2016 and 2021 found that 215 out of 878 examined individuals were diagnosed with the degenerative disease. While the study indicates a minimum prevalence of at least 25%, researchers suggest this is a conservative estimate because it only accounts for donated brains. Some estimates suggest the actual rate could be significantly higher. The findings link the disease, which causes cognitive impairment and emotional instability, to repeated head impacts. The results have prompted the NFL Players Association to describe the findings as a “call to action across the entire football ecosystem.” Experts have emphasized that the risks associated with concussions and sub-concussive hits necessitate safety improvements across all levels of the sport, including youth and college leagues. Newer research from Mass General Brigham further refines these risks, suggesting that the probability of contracting CTE doubles for every 2.6 years played. This data emphasizes that neurological damage often stems from repetitive subconcussive blows rather than single major impacts. Recent findings expand on these risks, noting that 97.7 percent of donated brains from the 2016–2021 period showed signs of the disease. The study linked CTE progression to cognitive decline, noting nearly 60 percent of analyzed donors had been diagnosed with dementia during their lifetime. In response, safety measures are evolving; Stanford University researchers are studying sensor-equipped mouthguards to measure impact forces, and helmet manufacturers are focusing on mitigating lower-impact hits. Additionally, the NFL has implemented Guardian Caps—padded foam covers for helmets—during training and permitted their use in official games starting in 2024. ## Timeline ### 2026-09-09: NFL players face high CTE risks in new brain disease study A study shows at least 25% of deceased NFL players died with CTE. Researchers and manufacturers are now using new technology and padded helmet covers to mitigate repetitive head impact risks. 2 sources. https://clstr.news/cluster/nfl-players-face-high-cte-risks-in-new-brain-disease-study ### 2026-09-04: NFL players face high CTE risks in new brain study A study of 235 deceased NFL players found that 215 showed signs of CTE, highlighting the severe neurological risks posed by repetitive subconcussive hits in professional football. 2 sources. https://clstr.news/cluster/nfl-players-face-high-cte-risks-in-new-brain-study ### 2026-08-31: NFL players face high risk of CTE, study finds A study of former NFL players found that at least 25% had chronic traumatic encephalopathy (CTE), a degenerative brain disease caused by repeated head impacts, prompting calls for increased safety. 2 sources. https://clstr.news/cluster/nfl-players-face-high-risk-of-cte-study-finds-3 ### 2026-08-27: NFL players face high risk of CTE, new study finds A BMJ study reveals that at least 25% of former NFL players who died between 2016 and 2021 had CTE, with some estimates suggesting the actual prevalence could be much higher. 11 sources. https://clstr.news/cluster/nfl-players-face-high-risk-of-cte-new-study-finds --- Cite as: CTE prevalence and safety responses in NFL. CLSTR, https://clstr.news/situations/cte-prevalence-in-former-nfl-players