Researchers already know that repeated hits to the head on the football field are linked to a degenerative brain disease, as seen in a number of retired NFL stars. Now, experts have turned their attention to ice hockey, another high-contact sport.
When studying whether the hits, year after year, can also be linked to chronic traumatic encephalopathy (CTE) in hockey, the Boston University research team found the link is there: Each additional year of playing ice hockey may increase a person's chance of developing CTE by about 23%, the investigators found.
And for each year a person played hockey, there was an associated 15% increased chance for progressing one CTE stage, according to the study.
"It's an important finding. It's something we can clearly communicate to clinicians, to parents, when making choices about activities that their children play or to young adults making choices about whether they want to continue to play to elite levels, that there is some inherent risk," said Dr. Jesse Mez. He is an associate professor of neurology at Boston University School of Medicine.
"And I think, similarly, when clinicians are taking care of folks who are experiencing cognitive symptoms or mood or behavior symptoms later in life, that queries about contact sports should be part of the assessment," Mez said.
The research group had previously investigated the links between football and CTE, studying players' brains after their death. Many former NFL athletes have been found to have CTE, including stars like Frank Gifford and Junior Seau. After seeing cases of hockey players with CTE in their brain banks, researchers hypothesized there might be a similar relationship.
'It's the repeated hits'
"What we've learned from football is that it's these repeated hits. Whether or not they cause a symptomatic concussion is almost irrelevant," Mez said. "It's the repeated hits over the course of a season that increase the risk for this disease."
While the new study shows the potential for danger applies to hockey as well as football, it can't calculate absolute risk, Mez noted.
"We can say that for each additional year, the risk increases, but we don't know what the overall risk is or what the baseline risk is for somebody who plays just a couple of years," Mez said.
The study looked at the brains of 74 people who played ice hockey, including seven who played as youths, 25 who played in high school, 22 who played at the junior or college level, and 19 who played professionally. One played at an unknown level. Almost half of the participants also played another contact sport, such as football. About 54% of the study's donors were diagnosed with CTE during an autopsy.
In conducting the study, the researchers worked with the Veteran Affairs-Boston University-Concussion Legacy Foundation Brain Bank and the Framingham Heart Study Brain Bank.
How to make play safer
Football has received more attention for CTE and that's why there are neurosurgeons on the sidelines for NFL games, said Dr. Ray Chu, who leads the team that does that service for the L.A. Rams.
Still, "I know very few neurosurgeons that would go out there and say, 'No one should ever play football' or 'no one should ever play ice hockey,'" said Chu, a neurosurgeon at Cedars-Sinai Medical Center in Los Angeles who was not involved in the study.
"I think there's the idea of 'how do we make it safer?'" Chu added.
That might include questioning a player who has just had a hit to determine if their balance, memory or thinking is off and they need to take a break rather than risking a second hit while their brain is still recovering, Chu said.
A solution for reducing CTE in football players could be transitioning younger players to flag football instead of tackle football. In hockey, options for reducing or delaying contact could include penalizing "checking," which involves crashing into an opponent who has the puck. Practices could involve fewer direct hits.
Mez said, "I don't feel like I'm in the business to tell people what to do or not to do, but I do think that making choices based on all of the information available is really important and valuable." However, he noted that further research is needed to confirm these results.
Individuals who have CTE can have cognitive symptoms, such as memory trouble and problems with executive functions, including multitasking and problem-solving. They may also have mood or behavioral issues, including impulsivity or a "short fuse," Mez said. The disease can eventually lead to more impairment and dementia.
CTE starts with abnormal accumulation of tau proteins in the frontal lobes of the brain, and then progresses through three additional stages. In stage four, individuals have widespread tau accumulation, brain shrinkage and associated dementia.
The findings will be presented at the American Academy of Neurology annual meeting, held April 2 to 7 in Seattle. Findings presented at medical meetings should be considered preliminary until published in a peer-reviewed journal.
The Alzheimer's Association has more on chronic traumatic encephalopathy.
SOURCES: Jesse Mez, MD, MS, associate professor, neurology, and Alzheimer's Disease Center Clinical Core associate director, Boston University School of Medicine, and member, American Academy of Neurology; Ray Chu, MD, neurosurgeon, department of neurosurgery, Cedars-Sinai Medical Center, Los Angeles, Calif.; American Academy of Neurology annual meeting, April 2 to 7, 2022, Seattle