Concussion study at Western University finds minor, repetitive hits change brains
It isn’t just major concussive blows but a series minor hits that can cause changes in athletes’ brains, a new study by Western University researchers says.
Even mild, repetitive hits to the head can cause subtle changes to the brains of otherwise healthy, symptom-free athletes, researchers say in a new study published online in the medical journal of the American Academy of Neurology.
“We were seeing both structural changes in the brain as well as adaptive, functional changes in the way the brain processes information that were similar to concussion but not as severe,” said Ravi Menon, the study’s principal investigator and a professor at Western’s Schulich School of Medicine and Dentistry.
“These changes were cumulative. If a woman played multiple seasons, the structural damage accrued over those multiple seasons. That suggests that even these lower-level impacts, over long periods of time, can have changes in both the structure and function of the brain.”
The five-year study followed 101 female athletes at Western. Of the group, 70 played rugby and 31 were rowers or swimmers. Researchers wanted to compare the brains of the athletes playing a contact sport with a similar group of high-level athletes involved in no-contact sports.
Athletes wore devices to record head impacts during practices and games to show the amount of impact they were experiencing in a regular season. Researchers also used MRI brain scans to look for changes in the structure of the brain’s white matter and how different areas of the brain communicate with one another.
The research team found rowers and swimmers did not experience any impacts, but 70 per cent of the rugby players sustained an average of three hits during two practices and one pre-season game.
In rugby players, study authors found changes in the nerve highways of the brain, Menon said. The changes increased over time in some players, worsening over multiple seasons. The same brain changes weren’t seen in the female rowers or swimmers.
“It’s clear that even sub-clinical impacts have an effect on the brain, and this has immediate implications for concussion research,” study author Kathryn Manning said in a statement.
“Though the long-term effects of sub-clinical impacts remain unclear, an effort to limit the number of impacts athletes experience in practice could be beneficial.”
Menon said rules against hits in practice or head protection for rugby players should be explored.
Though the latest study sheds light on the effect of mild repetitive hits in the brain, a next step would be to follow athletes with these brain changes longer term, Menon said.
“We’ve seen this cumulative damage, but what would be nice is if we look five years from now, if some of that structural damage recovers,” Menon said. “That’s a really important question.”