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. 2024 Dec 2;7(12):e2449106.
doi: 10.1001/jamanetworkopen.2024.49106.

Duration of Ice Hockey Play and Chronic Traumatic Encephalopathy

Bobak Abdolmohammadi  1   2 , Fatima Tuz-Zahra  3 , Madeline Uretsky  1   2 , Raymond Nicks  1   2   4   5 , Sydney Mosaheb  1   2 , Jacob Labonte  1   2 , Eukyung Yhang  3 , Shruti Durape  1   2   6 , Brett Martin  7 , Joseph Palmisano  7 , Christopher Nowinski  1   2   8 , Jonathan D Cherry  1   2   4   9 , Victor E Alvarez  1   2   4   5   6 , Bertrand R Huber  1   2   4   5   10 , Kristen Dams-O'Connor  11   12 , John Crary  12   13 , Brigid Dwyer  1   2   10   14 , Daniel H Daneshvar  15 , Lee E Goldstein  1   2   16   17   18 , Rhoda Au  1   2   6   10   19   20 , Douglas I Katz  1   2   10   14 , Neil W Kowall  1   2   4   10 , Robert C Cantu  1   2   21   22 , Robert A Stern  1   2   10   19   20   22 , Michael L Alosco  1   2   10 , Thor D Stein  1   2   4   5   6   9 , Yorghos Tripodis  1   2   3   6 , Ann C McKee  1   2   4   5   6   9   10 , Jesse Mez  1   2   6   10
Affiliations

Duration of Ice Hockey Play and Chronic Traumatic Encephalopathy

Bobak Abdolmohammadi et al. JAMA Netw Open. .

Abstract

Importance: Chronic traumatic encephalopathy (CTE) is a neurodegenerative tauopathy associated with repetitive head impacts (RHIs). Prior research suggests a dose-response association between American football play duration and CTE risk and severity, but this association has not been studied for ice hockey.

Objective: To investigate associations of duration of ice hockey play with CTE diagnosis and severity, functional status, and dementia.

Design, setting, and participants: This cross-sectional study was conducted among male brain donors in the Understanding Neurological Injury and Traumatic Encephalopathy and Framingham Heart Study Brain Banks whose primary RHI exposure was from ice hockey. Donors died, brains were donated, and data were collected between July 1997 and January 2023. Data analysis was conducted from January 2023 to May 2024.

Exposures: Ice hockey years played as an RHI proxy.

Main outcomes and measures: CTE neuropathological diagnosis, cumulative phosphorylated tau (ptau) burden across 11 brain regions commonly affected in CTE, informant-reported Functional Activities Questionnaire (FAQ) score at death, and consensus dementia diagnosis were assessed.

Results: Among 77 male donors (median [IQR] age, 51 [33-73] years), 42 individuals (54.5%) had CTE, including 27 of 28 professional players (96.4%). CTE was found in 5 of 26 donors (19.2%) who played fewer than 13 years, 14 of 27 donors (51.9%) who played 13 to 23 years, and 23 of 24 donors (95.8%) who played more than 23 years of hockey. Increased years played was associated with increased odds for CTE (odds ratio [OR] per 1-year increase, 1.34; 95% CI, 1.15-1.55; P < .001) and with increased ptau burden (SD increase per 1-year increase = 0.037; 95% CI, 0.017-0.057; P < .001) after adjusting for age at death, other contact sports played, age of first hockey exposure, concussion count, and hockey position. Simulation demonstrated that years played remained associated with CTE when years played and CTE were both associated with brain bank selection across widely ranging scenarios (median [full range] OR across all simulations, 1.34 [1.29-1.40]). Increased ptau burden was associated with FAQ score (βstandardized = 0.045; 95% CI, 0.021-0.070; P < .001) and dementia (OR per SD increase, 1.12; 95% CI, 1.01-1.26; P = .04) after adjusting for age at death, other contact sports played, hockey years played, enforcer status, age of first hockey exposure, concussion count, and hockey position.

Conclusions and relevance: In this study of male former ice hockey players, a dose-response association was observed between hockey years played and risk and severity of CTE. Simulation suggested that brain bank selection may not bias the magnitude of outcomes in the association.

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Conflict of interest statement

Conflict of Interest Disclosures: Dr Nowinski reported serving as a volunteer member of the Mackey-White Committee of the National Football League (NFL) Players Association, for which he receives travel support, and an advisor and options-holder with Oxeia Biopharmaceuticals, LLC, and StataDx; receiving travel support from the NFL, NFL Players Association, World Rugby, World Wrestling Entertainment (WWE), and All Elite Wrestling (AEW); serving as an expert witness in cases related to concussion and chronic traumatic encephalopathy (CTE) and receiving compensation for speaking appearances and serving on the Players Advocacy Committee for the NFL Concussion Settlement; and being employed by the Concussion Legacy Foundation, a 501(c)(3) nonprofit which receives charitable donations. Dr Dams-O’Connor reported receiving personal fees from various law firms outside the submitted work. Dr Daneshvar reported receiving personal fees for providing expert testimony related to traumatic brain injury and spinal cord injury and serving as a medical advisor and options holder for StataDx outside the submitted work. Dr Au reported receiving personal fees from Signant Health, Novo Nordisk, and Davos Alzheimer’s collaborative nonprofit organization outside the submitted work. Dr Stern reported receiving personal fees from Eisai outside the submitted work and royalties for published neuropsychological tests from Psychological Assessment Resources, Inc; owning stock options as a member of Board of Directors for King-Devick Technologies, Inc; receiving grants from the National Institutes of Health (NIH), Life Molecular Imaging Inc, and Rainwater Charitable Foundation Inc during the conduct of the study; and receiving an honorarium from the Michael J. Fox Foundation unrelated to this work and royalties from Oxford University Press Inc outside the submitted work. Dr Tripodis reported receiving personal fees from the American Medical Association outside the submitted work. Dr Mez reported receiving grants from the NIH outside the submitted work. No other disclosures were reported.

Figures

Figure 1.
Figure 1.. Distribution of Duration of Ice Hockey Play and Chronic Traumatic Encephalopathy (CTE) Photomontage
A, Violin plots display the distribution of duration of ice hockey play stratified by CTE diagnosis. B, The photomontage of stage II CTE shows hemispheric 50-μm tissue sections immunostained with AT8. Positive phosphorylated tau (ptau) immunostaining appears dark brown, showing a large CTE lesion in the left frontal lobe and right anterior frontal lobe. Pathognomonic CTE lesions (arrows) consisting of ptau neurofibrillary tangles and neurites around a central vessel are shown. Magnification is ×200.
Figure 2.
Figure 2.. Evaluating Linearity Assumption
A, The bar graph shows 2 + the log odds of the probability of chronic traumatic encephalopathy (CTE) by duration of hockey played in 3-year intervals. For durations of 0 to 6 years and 25 or more years, the log odds of CTE probability could not be calculated because no donors had CTE (for 0-6 years) or all donors had CTE (≥25 years). For the figure, log odds were calculated with probabilities of 1 of 7 CTE cases for durations of 0 to 6 years and 18 of 19 CTE cases for durations of 25 or more years. There were 0 of 6 donors, 4 of 11 donors (36.4%), 1 of 10 donors (10.0%), 5 of 14 donors (35.7%), 3 of 5 donors (60.0%), 4 of 5 donors (80.0%), 6 of 7 donors (85.7%), and 19 of 19 donors (100%) with CTE at 0 to 6, 7 to 9, 10 to 12, 13 to 15, 16 to 18, 19 to 21, 22 to 24, and 25 or more years of duration, respectively. B, The locally estimated scatterplot smoothing (LOESS) regression plot shows cumulative phosphorylated tau (ptau) burden by duration played.
See this image and copyright information in PMC

References

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