10 Things BU CTE Center Research Has Taught Us about the Brain Dangers of Contact Sports and Military Service
Top, from left: herreid/iStock; isitsharp/iStock; John Torcasio on Unsplash; skynesher/iStock; ActionPics/iStock. Bottom, from left: Matt Slocum via AP; Stein, et. al; Adam Glanzman/Getty Images; AP Photo/Matt York; gerenme/iStock
10 Things BU CTE Center Research Has Taught Us about the Brain Dangers of Contact Sports and Military Service
From amateur athletes’ brain injury risk to how sports hits change the brain’s white matter, here are some of the latest findings from BU researchers
Whether they’ve seen headlines about a former football star struggling in later life or about an athlete whose brain was donated to science after an untimely death, sports fans have become sadly familiar with the medical condition chronic traumatic encephalopathy, or CTE. In recent decades, the progressive degenerative disease has become a specter haunting contact sports, with research highlighting the heightened risk of CTE from repetitive hits to the head and growing numbers of former football, ice hockey, and other sports players being diagnosed postmortem.
Much of what we know about CTE, which can only be confirmed after death, is thanks to researchers at Boston University’s CTE Center. It’s a global leader in studying the disease, pioneering research on how CTE changes the brain, as well as what causes it and potential ways to diagnose it in life. Over the past 16 years, the center has been given more than 1,500 brains that were donated for research, published more than 100 studies on traumatic brain injury, and confirmed CTE in hundreds of former athletes.
As part of The Brink’s special CTE series, we’re highlighting our coverage of some of the center’s most recent and headline-making breakthroughs and studies.
Connection between Protein Buildup in the Brain and CTE Symptoms Edges Us Closer to Diagnosis during Life
A BU-led study published in the journal Molecular Neurodegeneration found a relationship between the accumulation of a protein, called tau, in the brain and the severity of cognitive and behavioral symptoms. “For the first time, we were able to show a clear dose-response relationship between the amount of CTE pathology and the severity of cognitive and functional symptoms, including problems with memory and executive function,” said Jesse Mez, a BU Chobanian & Avedisian School of Medicine associate professor of neurology. “These findings provide a clear step forward toward diagnosing CTE in life.” You can read more about the journey to diagnosing CTE here.
It’s Not Just Veteran Pro Athletes at Risk of CTE
In a study of 152 contact sports participants who had died under age 30, BU researchers discovered more than 40 percent—most of them amateur athletes—had signs of CTE. “It seems to be well accepted now that you can play at a very high level of elite American football or ice hockey and get CTE,” said Ann McKee, director of the BU CTE Center and a William Fairfield Warren Distinguished Professor. “But we’re seeing the beginnings of this disease in young people who were primarily playing amateur sports.”
Tackle Football Presents Another Danger: Parkinson’s Disease
Working with the Michael J. Fox Foundation, CTE Center researchers found that playing football increased the chances of a Parkinson’s disease diagnosis, or Parkinson’s-like symptoms. The longer the career, the higher the competitive level, the greater the risk. “Boxers have had a history of Parkinson’s, going back to the 1920s,” said the study’s corresponding author Michael L. Alosco, a BU Chobanian & Avedisian School of Medicine associate professor of neurology. “Fast forward to modern day, and there have been some interesting pathology studies that have linked repetitive head impact to things like Parkinson’s. Our goal was that we know this has been looked at in boxing, and in tissue studies of brains, but what about in living people?” A more recent study also showed that what some may have thought were Parkinson’s symptoms in life were actually instead connected to CTE.
Cumulative Force of Hits to the Head Major Predictor of Brain Disease
One of the largest studies ever on the causes of CTE in former football players found the estimated cumulative force of head impacts was a better predictor of the disease than how long someone played or how many hits they took. The study looked at 631 brains of former players. “I think that we’ve now demonstrated clearly that repetitive head impacts in football are a cause of CTE,” said Mez, a codirector of clinical research at the CTE Center. “Although similar relationships in other contact sports have not been studied in the way we have for football, there is growing evidence that similar relationships may exist.”
Football Hits Can Also Lead to Less White Matter in the Brain
The repeated hits to the head synonymous with football can lead to less white matter in the brain, whether or not someone also has CTE. According to CTE Center research, the earlier someone starts playing football, the greater their risk of structural damage to the brain; playing for more than 11 years also increases the chances of decreased white matter. “Just because you aren’t diagnosed with CTE doesn’t mean there isn’t something structurally damaged in the brain,” said Thor Stein, a Chobanian & Avedisian associate professor of pathology and laboratory medicine. “Damage to the white matter may help explain why football players appear more likely to develop cognitive and behavioral problems later in life, even in the absence of CTE.”
CTE Found in the Brains of Nearly 92 Percent of Ex-NFL Players Studied
At the peak of their football careers, they were heroes, revered athletes putting their bodies on the line to score a touchdown—or stop one. But figures from the CTE Center paint a bleak picture of the cost of a pro football career. In a 2023 report, the center said it had studied the brains of 376 former NFL players and found CTE in 91.7 percent of them. “There is a love for football by the public and individuals that transcends common sense,” said McKee, who spoke to The Brink about steps she felt the NFL could take to better protect players. “They are stuck in a denial because the game is so important to them that they refuse to look at the facts.”
Playing Contact Sports Could Mess with Your Sleep
In a study published in Acta Neuropathologica, BU researchers detailed a connection between CTE and rapid eye movement (REM) sleep behavior disorder. A rare condition, typically associated with Parkinson’s, it can mess with sleep paralysis, leading sufferers to almost literally live out their dreams—talking, flailing, kicking, punching, and grabbing when they should be resting peacefully. “Dreams can have very high emotional content, and when a person wakes up thrashing about, they’re really disturbed,” said Stein, director of molecular research at the CTE Center. “Repetitive head impacts may damage and disrupt cells in the brain’s sleep centers.” (The image at left shows part of the brainstem containing clusters of neurons implicated in regulating sleep.)
Every Three Years of Playing Tackle Football Doubles CTE Risk
Sports fans love statistics—but here are some numbers that will make football devotees wince. Every year of playing tackle football increases the risk of developing CTE by 30 percent. For every 2.6 years of play, the risk doubles. “We hope that these findings will guide players, family members, and physicians in making informed decisions regarding play,” said Mez.
BU Researchers Confirm Lewiston, Maine, Mass Shooter Had Brain Injury—but Not CTE
The CTE Center’s work isn’t just focused on contact sports like football and ice hockey; it also studies the effects of blasts and other impacts on military personnel and veterans. After a mass shooting in Lewiston, Maine, in October 2023, the state’s chief medical examiner’s office asked BU experts to perform a postmortem analysis of the shooter, a US Army reservist who was exposed to thousands of blasts in his lifetime. The BU team confirmed he had traumatic brain injury—but not CTE—and that it likely played a role in his behavioral symptoms.
Ice Hockey Increases CTE Risk—and Other Findings
With more than 100 papers, the CTE Center has covered a lot of research ground, finding that NFL athletes are four times more likely to die from amyotrophic lateral sclerosis (ALS) than the general population and that each additional year of ice hockey leads to a 23 percent increased chance of CTE. Want more on the center’s work? Check out our recent recap of some of its other biggest findings.
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