A study led by researchers from Boston University and published in the neurology journal Brain suggests that it’s repeated hits to the head—not concussions—that cause chronic traumatic encephalopathy (CTE), a progressive degenerative disease that is a known complication of repeated traumatic brain injuries.
The CTE study findings could dramatically change sports, especially for child athletes, and could mean new safety practices for professional leagues. Organizations like the NFL have focused on concussions only as a concern in athletes developing brain injuries. NFL officials have scrambled to prevent CTE after numerous football players, mostly retired, were identified to have the disease after their deaths.
Study Says Head Impact Must Be Reduced to Prevent CTE
The study, published on January 18, 2018, was conducted by Boston University, which has focused heavily on CTE in recent years. Its results confirmed something that researchers had been suspecting for some time.
“We’ve had an inkling that subconcussive hits—the ones that don’t [show] neurological signs and symptoms—may be associated with CTE,” Dr. Lee Goldstein, a lead investigator on the study and an associate professor at the BU School of Medicine, told NPR. “We now have solid scientific evidence to say that is so.”
The new CTE study shows that, unlike previously thought, “It’s the hits to the head, not concussion, that trigger CTE,” according to Goldstein. The researchers say that those repeated head injuries result in blood vessels leaking proteins into nearby brain tissues and causing inflammation.
Researchers Used Mice and the Brains of Deceased Teenage Athletes to Test for Brain Injuries
The BU study team made the connection between CTE and repetitive head injuries using data procured by performing post-mortem examinations on the brains of four teenage athletes (CTE is not diagnosed until after death). The teens had died one, two, 10, and 128 days after sustaining head injuries. Researchers contrasted that information with data obtained from the brains of four deceased teenage athletes who had not sustained head injuries recently and discovered some stark differences between them.
The teens who had suffered recent head injuries before dying showed varying post-trauma pathologies, abnormal tau accumulations, and even one case of early CTE.
To test their theory on why the head injuries led to those results, researchers used laboratory mice, finding that mice exposed to repeated impact to the head and blast exposures had “leaky blood vessels” in their brain, and “persistent changes in electrical functions.”
“The same brain pathology that we observed in teenagers after head injury was also present in head-injured mice,” Professor Goldstein said. “We were surprised that the brain pathology was unrelated to signs of concussion.”
Aaron Hernandez’ CTE Fits Research Findings
One of the most famous cases of CTE has been that of Aaron Hernandez, a former tight end for the New England Patriots, who killed himself in prison at age 27. A brain scan after Hernandez’s death revealed advanced, stage-three CTE, to a level that researchers described it as “the most severe case they had ever seen in someone of Aaron’s age.” They also said that the level of CTE Hernandez had would be more in line with a retired football player in his 60s.
It’s impossible to determine when the CTE took hold of Hernandez’ brain, but some believe he had the disease while playing for the Patriots, and that the aggression, lack of impulse control, dementia and mood swings that are symptoms of the disease could have played a role in the events of his life.
A confusing element of Hernandez’ advanced CTE, however, had been his lack of concussions, which were what researchers have long thought was the cause of CTE. Hernandez had one concussion during his tenure with the Patriots, and it was described as “minor.” It is possible that he had sustained other concussions during his youth, but the outcome still didn’t fit with expectations from experts. Until now.
Hernandez undoubtedly suffered repeated hits in his time in the NFL, and it could be those hits, not the sole documented concussion, that led to his shockingly advanced CTE.
CTE Study Could Shift NFL and NHL Focus from Concussion
Recent pressure from critics and researchers has forced athletic organizations like the NFL and NHL to make visible efforts to improve their concussion safety protocol. Elements like unaffiliated neurotrauma consultants on the sidelines have been added to NFL rules as recently as December 24, 2017. Still, concussion protocols still have their shortcomings.
The Seattle Seahawks came under scrutiny in November 2017, when quarterback Russell Wilson skipped out on a required medical examination after a concussion sent him to the sidelines. The team was eventually fined $100,000 for failing to comply with protocol.
The findings from this latest CTE study could force leagues to look not only at concussions but at more general hits—which often occur—and to determine a method for acknowledging the long-term impact those head injuries have on players.
Ann McKee was a coauthor on the Boston University study and is the director of the CTE Center at the University. She says the findings demand attention and rule revisions.
“The continued focus on concussion and symptomatic recovery does not address the fundamental danger these activities pose to human health,” McKee said.
The study could also alter legal proceedings in professional sports organizations. In the past, the NFL has often used concussions to determine whether they would compensate players and players’ families for long-term brain injuries, refusing to pay unless there were documented cases of concussion. If CTE is proven to be caused by repeated hits to the head, this restriction could be called into question.