Study Reveals High CTE Prevalence in Deceased Ex-NFL Players

What Happened

A new study, released on Tuesday, August 25, 2026, by Mass General Brigham, Boston University, and the Concussion & CTE Foundation, revealed that at least 25 percent of former NFL players who died between 2016 and 2021 were diagnosed with chronic traumatic encephalopathy (CTE). This degenerative brain disease is definitively linked to repeated blows to the head, a common occurrence in professional football. The findings, published in The British Medical Journal, indicate a significantly higher occurrence rate than previously reported in similar studies, prompting renewed concerns about player safety in the sport. The research specifically focused on a cohort of 878 former NFL players who passed away within the specified five-year window, with a subset of 235 donating their brains for post-mortem analysis, the only method for definitive CTE diagnosis.

The study's lead author, Dr. Daniel Daneshvar, emphasized that the 25 percent estimate represents the 'low end' of the potential prevalence. Researchers calculated this figure by extrapolating from the donated brains to the entire population of deceased former NFL players from that period. The NFL, through a spokesperson to CBS News, stated its ongoing commitment to 'continuously striving to make the game of football safer' and implementing 'strategies to reduce concussions and head impacts.' The NFL Players Association (NFLPA) also issued a statement to ESPN, calling the findings a 'sobering reminder that football carries real risks' and reinforcing its priority of 'improving player safety and supporting players throughout their lives.'

What the Evidence Establishes

The evidence establishes a substantial prevalence of CTE among deceased former NFL players, with the study pinpointing a minimum of 25 percent for those who died between 2016 and 2021. This figure is derived from a detailed analysis of 235 donated brains from a total of 878 former NFL players who passed away in that timeframe. Of these 235 donated brains, a striking 215, or 91.4 percent, were found to contain CTE. Researchers then adjusted this high percentage to account for the players who did not donate their brains, arriving at the 'at least 25 percent' estimate for the broader population. The estimated range for CTE prevalence among all ex-NFL players who died during this period was between 24.5% and 97.7%, with researchers suggesting the 'true prevalence likely lies somewhere in the middle.'

Beyond the prevalence, the study also strengthened the link between severe CTE and dementia. Researchers found that 61.3 percent of the brains diagnosed with CTE also met the clinical criteria for dementia. This specific finding underscores the severe neurological consequences associated with the disease. The collaborative effort by Mass General Brigham, Boston University, and the Concussion & CTE Foundation, and its publication in The British Medical Journal, lend significant scientific weight to these conclusions. The methodology, relying on post-mortem brain analysis, is currently the only definitive way to diagnose CTE, making brain donation programs critical for this research.

Where the Accounts Conflict

The two primary sources, Breitbart and Daily Caller, present a largely consistent account of the study's findings, with no significant factual conflicts regarding the core data. Both outlets accurately report the central finding that 'at least 25 percent' of deceased former NFL players from 2016 to 2021 had CTE, as published in The British Medical Journal. They both cite the same research institutions: Mass General Brigham, Boston University, and the Concussion & CTE Foundation. The timeframe of the study (2016-2021) and the total number of deceased players (878) are also consistently reported.

A minor difference in emphasis can be observed in the reporting of the estimated prevalence range. While Breitbart notes the range of 'between 24.5% and 97.7%' and the researchers' statement that 'The true prevalence likely lies somewhere in the middle,' the Daily Caller specifically quotes Dr. Daniel Daneshvar, the study’s lead author, stating that the 25 percent estimate is on the 'low end.' This slight variation in framing does not contradict the data but rather highlights different aspects of the researchers' own caveats regarding the exact prevalence. Both sources acknowledge the difficulty in determining the 'true' prevalence due to the reliance on donated brains, a consistent point across the reporting.

Context and Stakes

The context for this study is a decades-long debate and increasing scientific understanding of the long-term neurological impacts of playing professional football. Previous research, notably from Boston University's CTE Center, has consistently identified CTE in a high percentage of donated brains from former players, but this new study attempts to estimate prevalence within a broader population of deceased players. The 'at least 25 percent' figure, even at its low end, represents a significant public health concern for former athletes and carries substantial implications for the National Football League, its player safety protocols, and its public image. The NFL has faced numerous lawsuits and public scrutiny over its handling of concussion risks and CTE awareness, leading to significant financial settlements and changes in game rules.

The stakes are high for the NFL, which continues to invest in player safety initiatives and research. The league's statement to CBS News, emphasizing its efforts to 'reduce concussions and head impacts,' reflects an ongoing attempt to mitigate these risks and address public and player concerns. For the NFL Players Association, the findings reinforce their 'core priorities' of 'improving player safety and supporting players throughout their lives,' suggesting continued advocacy for enhanced resources and care. Beyond the professional league, these findings also impact youth and amateur football, prompting questions about the safety of the sport at all levels and potentially influencing parental decisions regarding participation. The study adds further scientific weight to the argument that football carries inherent, long-term health risks that extend beyond a player's active career.

What to Watch Next

Following the publication of this study, several developments warrant close observation. The NFL's response will be critical; while a general statement has been issued, specific new initiatives or increased funding for CTE research and player support programs could be announced in the coming days or weeks. Historically, major CTE findings have often prompted the league to publicly reaffirm its commitment to safety and sometimes introduce new rule changes or equipment standards. Attention should also be paid to the NFL Players Association, which has called the findings a 'call to action.' The NFLPA may push for more robust collective bargaining agreement provisions related to long-term player health, including expanded access to care and support for former players affected by neurological conditions.

Further scientific research will also be a key area to watch. The study's authors noted that the 'true prevalence likely lies somewhere in the middle' of their estimated range, indicating a need for more comprehensive data collection methods that do not rely solely on brain donations. Advances in live-person CTE diagnosis, though currently unavailable, would revolutionize research and player management. Additionally, the legal landscape surrounding CTE and professional sports could see renewed activity. New class-action lawsuits or expansions of existing litigation against the NFL, leveraging the study's findings as fresh evidence of prevalence, are a distinct possibility. Public discourse and parental attitudes towards youth football participation may also shift, potentially leading to increased pressure on youth leagues to adopt stricter safety protocols and reduce contact.

Bottom Line

The study published in The British Medical Journal establishes that at least 25 percent of former NFL players who died between 2016 and 2021 had chronic traumatic encephalopathy (CTE). This finding, derived from a significant sample of donated brains, indicates a higher prevalence than previously estimated and reinforces the severe neurological risks associated with repeated head trauma in professional football. The research also highlights a strong correlation between CTE and dementia, with over 61 percent of CTE-diagnosed brains also meeting dementia criteria. While the NFL and NFLPA have acknowledged the findings and reiterated commitments to player safety, the study underscores the ongoing, systemic challenge of mitigating long-term brain injury in the sport.

The implications extend beyond the professional league, influencing discussions about player welfare, the future of football at all levels, and the need for continued scientific inquiry into brain health. The study's methodology, relying on post-mortem analysis, emphasizes the limitations in current diagnostic capabilities and the importance of brain donation for advancing understanding. This new data point will likely fuel further advocacy for enhanced safety measures, support for affected former players, and potentially new legal challenges, maintaining CTE as a central issue for the sport's stakeholders.