Eighteen of the 19 NHL players whose brains were studied after death were discovered to have CTE, the neurodegenerative disease that stems from repeated traumatic brain injuries.
The study from the Boston University CTE Center announced Wednesday revealed that the odds of the players developing chronic traumatic encephalopathy increased significantly — by 34 percent — with each year played.
A new study of male ice hockey players provides sobering data linking the duration of playing with the likelihood that repetitive head impacts will cause brain injuries.
The brains of 77 deceased male amateur and professional ice hockey players were donated by their families. Researchers stressed that since families are more likely to donate brains of symptomatic players, the results should not be confused with the prevalence of CTE in the target population.
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Still, the results strongly suggest a relationship of developing and suffering from the disease with how long players compete: None of the six players who competed for six years or fewer were discovered to have CTE.
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“Ice hockey players with longer careers not only were more likely to have CTE, but they also had more severe disease,” said corresponding author Jesse Mez, co-director of clinical research at the CTE Center and associate professor of neurology at Boston University Chobanian & Avedisian School of Medicine, n a press release. “We hope this data will help inspire changes to make the game safer as well as help former ice hockey players impacted by CTE get the care they need.”
Twenty-seven of 28 professional hockey players had the CTE pathology. All nine of the non-NHL professional player population had it.
Among college, junior, and semi-pro players, 13 of 28, or 46 percent, had CTE.
Ten percent, 2 of 21, of youth and high school players had CTE.
The study also looked into the difference in CTE diagnosis between players who were enforcers and those who were not.
Eighteen of the 22 enforcers had CTE, but the differences between the roles were not statistically significant when the duration of the respective careers were factored in.
“Enforcers have dominated the CTE conversation, but our findings provide the most evidence for the cumulative amount of play as the predominant risk factor for CTE,” said Mez. “Enforcers had about twice the odds of developing CTE, but the takeaway here is that non-enforcers are getting CTE, as well. Ice hockey players skate quickly, and checking leads to impacts with other players, the ice, boards, and glass. We think years of play is a proxy for these impacts that are harder to measure directly but are likely what are leading to the disease.”
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Ice hockey joins football and rugby as sports that show a relationship between CTE severity and the years spent playing.
The risk of CTE among female ice hockey players, where the checking rules are different, remains unknown.
Families and athletes concerned about cognitive or behavioral symptoms that could be signs of CTE are encouraged to visit https://concussionfoundation.org/helpline.
Michael Silverman can be reached at michael.silverman@globe.com.