Since the degenerative brain disease known as C.T.E. was first scientifically linked to football about 20 years ago, and as hundreds of former professional football players have been diagnosed with the disease after their deaths, a haunting question has lingered:
Just how many N.F.L. players will end up with C.T.E.?
New data provides a sobering indication: At least one in four of all the people who have played in the N.F.L. might expect to end up with chronic traumatic encephalopathy, according to a study of hundreds of cases over a recent six-year period.
Researchers considered every former N.F.L. player who died from 2016 to 2021. There were 878. Some died in their 20s, some in their 80s, most in between.
The study’s main finding was simple math: At least 215 of those 878 former players — 24.5 percent — had C.T.E.
The actual prevalence could be far higher. The roughly 25 percent rate does not consider the 643 brains that were not examined. Some of those, maybe many of them, likely had C.T.E. too.
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C.T.E. is a progressive neurological disease caused by repeated impacts to the head. It can be definitively diagnosed only by examining the brain after death.
Studies have shown that the rate of C.T.E. in people who have not sustained repeated impacts to the head is nearly zero.
If the new study’s statistics were applied to today’s players — 1,696 on the league’s 32 regular-season rosters, not including more than 500 members of practice squads and those ineligible due to injury — at least 400 of them would be diagnosed with C.T.E.
Experts say that the rate of brain disease represents an occupational safety hazard with little comparison in the American workplace.
“There are workers who’ve been exposed to high levels of asbestos exposure, which leads to very high rates of lung disease,” said David Michaels, who led the Occupational Safety and Health Administration during the Obama administration and is now a professor at the George Washington School of Public Health. “And certainly, you know, a lifetime working in coal mines leads to very high risk of black lung disease.
“But a degenerative neurological disease — I’ve never seen anything comparable.”
C.T.E. was first discovered in boxers nearly a century ago and termed “dementia pugilistica.” Symptoms can include memory loss, confusion and uncharacteristic mood swings, decreases in executive function and increases in erratic and impulsive behavior, including addiction.
These days, C.T.E. is most commonly associated with football players, but it has been found in the brains of other athletes who sustained repetitive blows to the head, including hockey, rugby and soccer players, as well as wrestlers and bobsledders. Those in the military who work with artillery also seem susceptible to the disease.
For years, the N.F.L. downplayed the risks of repeated head trauma, often insisting that not enough is known about C.T.E. to draw conclusions about its dangers, origins and prevalence. Uncertainty has left room for inaction; scientists have yet to decipher, among many things, why some people can play football for decades and not get C.T.E., while others have had severe cases in their teens.
But the prevalence rate now reported by researchers might be hard to ignore. It is the latest research from neuropathologists and other scientists mostly affiliated with Mass General Brigham, Boston University and the UNITE Brain Bank, which have led C.T.E. research and handled most donated brains of former athletes over the past two decades.
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Researchers involved in this study, published on Tuesday in The BMJ, hope to produce a subsequent paper in the coming months estimating the overall rate of C.T.E. in all N.F.L. players at the time of their death.
Making such an estimation is complicated by unknowns. What is certain, researchers said, is that C.T.E. is preventable.
“We know what’s causing it,” said Dr. Daniel Daneshvar, the lead author of the study, the chief of brain injury rehabilitation at Spaulding Rehabilitation Hospital and an associate professor at Harvard Medical School. “It’s a neurodegenerative disease where we know and have complete control over the risk. And understanding the extent of that risk is one of the steps into making sure that we can mitigate and decrease that risk.”
Dr. Daneshvar said that the biggest predictor of C.T.E. is the cumulative force of hits to a head over a lifetime — including those sustained before reaching the N.F.L.
“We can change that cumulative force without changing the game of football,” he said, suggesting that children refrain from playing tackle football and that teams at all levels eliminate hits during practices.
Just how many N.F.L. players will end up with C.T.E.?
New data provides a sobering indication: At least one in four of all the people who have played in the N.F.L. might expect to end up with chronic traumatic encephalopathy, according to a study of hundreds of cases over a recent six-year period.
Researchers considered every former N.F.L. player who died from 2016 to 2021. There were 878. Some died in their 20s, some in their 80s, most in between.
The study’s main finding was simple math: At least 215 of those 878 former players — 24.5 percent — had C.T.E.
The actual prevalence could be far higher. The roughly 25 percent rate does not consider the 643 brains that were not examined. Some of those, maybe many of them, likely had C.T.E. too.
Advertisement
SKIP ADVERTISEMENT
C.T.E. is a progressive neurological disease caused by repeated impacts to the head. It can be definitively diagnosed only by examining the brain after death.
Studies have shown that the rate of C.T.E. in people who have not sustained repeated impacts to the head is nearly zero.
If the new study’s statistics were applied to today’s players — 1,696 on the league’s 32 regular-season rosters, not including more than 500 members of practice squads and those ineligible due to injury — at least 400 of them would be diagnosed with C.T.E.
Experts say that the rate of brain disease represents an occupational safety hazard with little comparison in the American workplace.
“There are workers who’ve been exposed to high levels of asbestos exposure, which leads to very high rates of lung disease,” said David Michaels, who led the Occupational Safety and Health Administration during the Obama administration and is now a professor at the George Washington School of Public Health. “And certainly, you know, a lifetime working in coal mines leads to very high risk of black lung disease.
“But a degenerative neurological disease — I’ve never seen anything comparable.”
C.T.E. was first discovered in boxers nearly a century ago and termed “dementia pugilistica.” Symptoms can include memory loss, confusion and uncharacteristic mood swings, decreases in executive function and increases in erratic and impulsive behavior, including addiction.
These days, C.T.E. is most commonly associated with football players, but it has been found in the brains of other athletes who sustained repetitive blows to the head, including hockey, rugby and soccer players, as well as wrestlers and bobsledders. Those in the military who work with artillery also seem susceptible to the disease.
For years, the N.F.L. downplayed the risks of repeated head trauma, often insisting that not enough is known about C.T.E. to draw conclusions about its dangers, origins and prevalence. Uncertainty has left room for inaction; scientists have yet to decipher, among many things, why some people can play football for decades and not get C.T.E., while others have had severe cases in their teens.
But the prevalence rate now reported by researchers might be hard to ignore. It is the latest research from neuropathologists and other scientists mostly affiliated with Mass General Brigham, Boston University and the UNITE Brain Bank, which have led C.T.E. research and handled most donated brains of former athletes over the past two decades.
Advertisement
SKIP ADVERTISEMENT
Researchers involved in this study, published on Tuesday in The BMJ, hope to produce a subsequent paper in the coming months estimating the overall rate of C.T.E. in all N.F.L. players at the time of their death.
Making such an estimation is complicated by unknowns. What is certain, researchers said, is that C.T.E. is preventable.
“We know what’s causing it,” said Dr. Daniel Daneshvar, the lead author of the study, the chief of brain injury rehabilitation at Spaulding Rehabilitation Hospital and an associate professor at Harvard Medical School. “It’s a neurodegenerative disease where we know and have complete control over the risk. And understanding the extent of that risk is one of the steps into making sure that we can mitigate and decrease that risk.”
Dr. Daneshvar said that the biggest predictor of C.T.E. is the cumulative force of hits to a head over a lifetime — including those sustained before reaching the N.F.L.
“We can change that cumulative force without changing the game of football,” he said, suggesting that children refrain from playing tackle football and that teams at all levels eliminate hits during practices.
