New research is putting football’s long-term brain health crisis back under the spotlight — and scientists say the real figure could be considerably higher.
A new study has found that at least one in four former NFL players who died between 2016 and 2021 had chronic traumatic encephalopathy (CTE), a degenerative brain disease associated with repeated head impacts.
Researchers examined a group of 878 former NFL players who died during the six-year period. Of those, 235 had donated their brains for research, and 215 of the donated brains showed CTE-related pathology.
The findings, reported Tuesday, add to a growing body of evidence examining the long-term neurological consequences of playing professional American football.
Why researchers call 25% a “minimum” estimate
The 25% figure should not be interpreted as meaning that exactly one-quarter of all former NFL players have CTE.
CTE can currently be definitively diagnosed only through examination of brain tissue after death. That makes it extremely difficult for scientists to determine its true prevalence among living or deceased players.
The researchers therefore used multiple sources of information to estimate how common the disease may have been among the players who died during the study period. Because only a portion of the deceased players donated their brains, the study describes 25% as being at the low end of the possible range.
That distinction is important because people who donate their brains for CTE research may not represent the wider population of former players. Earlier Boston University research has similarly warned that high rates found in brain-bank samples cannot simply be applied to every current or former NFL player.
The findings come amid a much larger warning about NFL health
The new CTE findings arrive shortly after another major study examined the mortality records of nearly 20,000 NFL players.
That research, published in EClinicalMedicine, followed 19,824 players who debuted between 1960 and 2019 and found that NFL players had substantially higher rates of death from neurodegenerative diseases than the general population.
Researchers reported a 3.94-fold higher rate of neurodegenerative mortality among NFL players. Death from dementia was about 3.8 times higher, while Parkinson’s disease mortality was about 3.88 times higher. ALS mortality was also elevated, at roughly 4.55 times the expected rate.
The risk was even more pronounced among players who died before age 60. Researchers found more than a 12-fold increase in neurodegenerative mortality in that younger group compared with the general population. Players who spent at least five seasons in the NFL also had nearly twice the neurodegenerative mortality risk of those who played one to four seasons.
The biggest concern may begin before the NFL
Researchers say the neurological burden associated with football cannot necessarily be attributed solely to time spent in the NFL.
Daniel Daneshvar, one of the researchers involved in the work, noted that many of the head impacts experienced by former NFL players occurred before they reached the professional level, including during college, high school and youth football.
That means the cumulative exposure may begin years before an athlete ever reaches the NFL. Researchers have therefore argued that reducing repetitive head impacts during practices — not just during games — could be an important part of prevention efforts.
According to the researchers, a substantial share of head impacts occur during practice, making practice-contact policies potentially important at multiple levels of the sport.
What exactly is CTE?
CTE is a neurodegenerative disease associated with repetitive head impacts, including impacts that may not necessarily produce a diagnosed concussion.
The disease involves abnormal accumulation of phosphorylated tau protein in the brain. Researchers have associated CTE pathology with problems involving memory, thinking, mood and behavior, although the presence of CTE pathology does not mean every person will experience the same symptoms.
Importantly, symptoms such as depression, memory problems or cognitive decline cannot by themselves establish that someone has CTE. Similar symptoms can occur with numerous other medical conditions, and researchers continue to study how CTE pathology relates to clinical symptoms during life.
NFL says player safety remains a priority
The NFL has said it continues to work on reducing concussions and head impacts and has expanded health resources for former players.
In a statement reported by Reuters and NPR, the league said it was continuing to implement strategies designed to make football safer and encouraged former players with health concerns to use available resources and seek treatment.
The league has already introduced changes aimed at limiting certain forms of contact and reducing head-impact exposure, although researchers say further reductions may be needed throughout the football system.
A growing scientific picture — but not the final answer
The latest findings do not establish that playing in the NFL guarantees CTE or that every former player faces the same neurological risk.
What they do show is a widening scientific concern: former NFL players have unusually high rates of neurodegenerative disease, while CTE has repeatedly been identified in the brains of deceased football players who underwent postmortem examination.
The challenge now is determining exactly how widespread CTE is, why some players develop severe disease while others do not, and how much risk comes from the total number and intensity of head impacts accumulated throughout an athlete’s life.
Researchers are also working toward a major breakthrough: developing reliable methods that could eventually help identify CTE in living people. For now, however, definitive diagnosis still requires examination of brain tissue after death.
And that leaves football facing a question that is becoming increasingly difficult to ignore:
How much brain trauma is too much — and how early should the sport begin preventing it?
Leave a Reply