To investigate the relationship between years of ice hockey play and risk for CTE neuropathology at autopsy.

Chronic traumatic encephalopathy (CTE) is a neurodegenerative disease associated with exposure to repetitive head impacts (RHI) including from contact sports and military service. Previous work showed a dose-response relationship between CTE risk and severity and years of American football play. A similar dose-response relationship for ice hockey has not been investigated.

74 consecutive brain donors who played ice hockey from the Veterans Affairs-Boston University-Concussion Legacy Foundation and Framingham Heart Study Brain Banks [age range: 13-91; highest level of play: 7 (9%) youth, 25 (34%) high school, 22 (30%) juniors/college, 19 (26%) professional (1 unknown); 34 (46%) played an additional contact sport, including 32 (43%) who played American football] were assessed for CTE diagnosis, stage (0-IV) and cumulative neurofibrillary tangle burden across 11 brain regions commonly affected by CTE (range: 0-33). We estimated the association of duration of ice hockey play in years with each neuropathological outcome in linear models adjusted for age at death and duration of football play.

40 donors were diagnosed with CTE (54%). A dose-response relationship was observed between duration of ice hockey play and each outcome. Each additional year of play corresponded to a 23% increase in odds for having CTE (95% CI: 11%-36%; p<0.01), a 15% increase in odds for increasing one CTE stage (95% CI: 8%-22%; p<0.01), and a 0.03 SD increase in cumulative NFT burden (95% CI: 0.01-0.05; p<0.01). When limited to those who played hockey as their primary source of exposure (n=56), results remained similar.

This is the first study to find a dose-response relationship between years of ice hockey play and CTE risk and severity. Increasing ice hockey play may pose an increasing risk for CTE in a similar manner as American football play.