Study suggests blows to the head that don’t cause concussions can still cause CTE

Chronic traumatic encephalopathy (CTE) is a disease that has been exhibited in hundreds of athletes who have incurred repeated blows to the head, throughout…

By: Tim Bissell | 5 years ago
Study suggests blows to the head that don’t cause concussions can still cause CTE
Bloody Elbow 2.0 | Anton Tabuena

Chronic traumatic encephalopathy (CTE) is a disease that has been exhibited in hundreds of athletes who have incurred repeated blows to the head, throughout their careers in contact and combat sports. CTE causes parts of the brain to slowly die, resulting in issues such as memory loss, depression, dementia, and increased suicidality.

The damage to the brain is caused by a protein named pTau. It was previously thought that this protein was released inside the brain, in greater amounts than what occurs naturally, when concussion symptoms are experienced.

However, a new study by the Boston University School of Medicine and College of Engineering, suggests that the process that culminates in CTE does not require any concussion symptoms at all. In other words, blows to the head — which do not cause the sufferer to be knocked unconscious, experience dizziness, or lingering headaches — are enough to cause degenerative damage to the brain.

“The concussion is really irrelevant for triggering CTE,” said Dr. Lee Goldstein, an associate professor at Boston University, when interviewed by The Washington Post. “It’s really the hit that counts.”

Goldtein’s study involved the analysis of teenage brains that had suffered brain injuries alongside the brains of mice that had been made to endure head trauma.

“We were surprised that the brain pathology was unrelated to signs of concussion,” he said. “Including altered arousal and impaired balance, among others. Our findings provide strong causal evidence linking head impact to TBI and early CTE, independent of concussion.”

Goldstein said that these findings may explain why approximately 20 percent of athletes with CTE never suffered a diagnosed concussion.

The study also succeeded in adding much needed clarity to the confusing world of head injuries; which often sees concussions, traumatic brain injuries (TBIs), and CTE mislabeled and misunderstood.

“So concussion may or may not be a TBI and equally important not having a concussion may or may not be associated with a TBI. A concussion doesn’t tell you anything about a TBI. Nor does it tell you anything about CTE,” said Goldstein.

Goldstein tried to further simplify things for The Post.

According to him, a concussion is a syndrome; meaning it is a collection of symptoms. The symptoms which have been grouped into what we refer to as a concussion include dizziness, loss of consciousness, light sensitivity, and headaches. These symptoms are usually triggered when the brain is made to rotate within the skull because of force.

A TBI is different from concussions. These are actual injuries that involve damage to brain tissue. These can be caused by the brain shifting back and forth, or side to side, violently within the brain as a result of force. This was the case in the death of Tim Hague last year.

CTE is a “bona fide neurodegenerative disease,” said Goldstein. “It will progress independently of whether you have future hits and a lot of people think that the injury is the disease and it’s not. There is an injury and then it goes on to spread in the brain, like other neurodegenerative diseases.”

It is still generally believed that blows to the head which are severe enough to cause concussion symptoms will result in CTE. However, this new study showed that blows which do not trigger the concussion symptoms can also trigger the disease.

Goldstein said these findings meant that concussion protocols in organized sports might not do anything to prevent someone eventually suffering from CTE. Concussion protocols usually assess athletes who have suffered a blow to the head to determine if they have concussion like symptoms. If they do, athletes are generally pulled from a game or prescribed a period of inactivity to ‘recover.’

However, athletes who have been hit in the head, but do not show concussion symptoms, often continue to play (or fight) and then endure additional subconcussive blows to the head; which we now know can cause CTE.

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About the author
Tim Bissell
Tim Bissell

Tim Bissell is a writer, editor and deputy site manager for Bloody Elbow. He has covered combat sports since 2015. Tim covers news and events and has also written longform and investigative pieces. Among Tim's specialties are the intersections between crime and combat sports. Tim has also covered head trauma, concussions and CTE in great detail.

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