A study published in BMJ in August 2026 found CTE in 215 of 235 brains donated by former NFL players or their families — about 91.5% — while 97.7% was the maximum possible prevalence estimate. The study also estimated a more conservative minimum CTE prevalence of nearly 25% across all former players who died between 2016 and 2021.
The research, detailed by The Oklahoman in a piece authored by Adam Cohen, senior vice president and general counsel of the Oklahoma Medical Research Foundation, and Dr. Hal Scofield, a physician-scientist at the foundation who also serves as associate chief of staff for research at the Oklahoma City VA Medical Center, examined brains donated by former players or their families. Researchers looked at roughly one-quarter of former players who died during that five-year window, and the brain-donation group was self-selecting, mostly including people who had experienced symptoms of brain disease while living — a factor the authors say inflates the 97% figure relative to the broader population of former players.
CTE is a brain disease caused by repeated head trauma, and severe cases are accompanied by dementia in almost all instances, according to the same report. A separate analysis led by Dr. Daniel Daneshvar examined 878 former NFL players who died between 2016 and 2021, confirming CTE in 215 of 235 donated brains to establish a minimum population prevalence baseline of 24.5%, as detailed by CBS Sports. That same research found 61.3% of brain donors with CTE met clinical criteria for dementia, with the rate climbing to 90.4% among those with severe Stage IV disease, according to Epocrates.
Cumulative Exposure Raises CTE Risk
CTE risk increases with cumulative exposure to repeated head impacts, including sub-concussive blows that never trigger a diagnosed concussion, and years of football play increased the odds of CTE by 30% per additional year, per the same Oklahoman report. CTE remains nearly non-existent in the general population, with community brain bank data showing detection in less than 1% of non-athletes, according to CBS Sports.
Not everyone agrees the highest-end estimates tell the full story. In an August 2026 BMJ rapid response, researchers with Harvard's Football Players Health Study argued that upper-range CTE prevalence estimates of up to 97% are inflated by selection bias in brain bank donations. They said their concerns do not argue against CTE being a serious issue, according to The BMJ. Researchers involved in the broader study acknowledge the true prevalence figure likely sits somewhere between the conservative 24.5% baseline and the higher self-selected estimate, though the exact number remains unresolved.
Guardian Caps and Q-Collar Face Mixed Evidence
The NFL has pointed to a 52% decline in preseason concussions among players wearing Guardian Caps — soft padded covers worn over helmets — compared with previous averages, the NFL reported in 2024. But when analysis was restricted to helmet-shell impacts specifically, Guardian Caps showed no observed effect, and a study of 2,600 high-school football players found the caps produced no significant reduction in concussions overall. A separate analysis of 7,500 actual impacts experienced by college players, using mouthguard instrumentation, found no significant reduction in impact force associated with the caps.
League-wide, the NFL recorded 182 total concussions across all 2024 practices and games, a 17% drop from 2023 and the lowest single-season total since tracking began in 2015, a period during which the league expanded in-game Guardian Cap options, according to DAZN News. Independent researchers note that Guardian Caps show limited force reduction in controlled studies, even as the league cites the overall concussion decline as evidence the equipment works.
The Q-Collar, a band worn around some players' necks, applies gentle pressure to the jugular vein, theoretically increasing the amount of blood in the skull to reduce brain movement against it during impacts. The FDA authorized marketing of the device in 2021, but the study underlying that approval did not demonstrate that Q-Collars prevent concussions or serious brain injuries, and a BMJ follow-up investigation raised substantial questions about the study's design and statistical analyses.
Q30 Innovations says the Q-Collar's 2021 FDA clearance was supported by more than 28 studies involving over 500 athletes, per Q30 Innovations. Q-Collar claims of brain protection rest on subtle MRI biomarkers rather than proven concussion prevention, independent researchers note.
Settlement Payouts and Youth Football Rules
Hoodline has previously covered the human toll of these findings, including the death of Super Bowl champ Jordan Devey at 38 and 49ers legend Roger Craig's disclosure of vascular dementia during his Hall of Fame speech.
A 2025 California bill, AB 708, proposed requiring youth tackle leagues to allow soft-shelled helmet covers like Guardian Caps; existing statutory limits restrict full-contact practice to 30 minutes per day and two days per week, according to LegiScan. The Oklahoman report frames these equipment debates against a broader public health message: preventing brain trauma requires reducing total head-impact exposure, through measures including fewer full-contact practices, fewer hits in practice, and starting children in tackle football at later ages.
