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Association of Concussion Symptoms With Testosterone Levels and Erectile Dysfunction in Former Professional US-Style Football Players

Educational Objective
To determine whether professional US-style football players with a history of multiple concussion symptoms are more likely to report indicators of low testosterone levels or erectile dysfunction.
1 Credit CME
Key Points

Question  Are professional US-style football players with a history of multiple concussion symptoms more likely to report indicators of low testosterone levels or erectile dysfunction (ED)?

Findings  In this cross-sectional study of 3409 former players, a monotonically increasing association was found between the number of concussion symptoms and the odds of reporting an indicator of low testosterone level and ED.

Meaning  Concussion symptoms among former football players were associated with low testosterone levels and ED indicators, suggesting that men with a history of head injury may benefit from discussions with their health care clinicians regarding these treatable outcomes.


Importance  Small studies suggest that head trauma in men may be associated with low testosterone levels and sexual dysfunction through mechanisms that likely include hypopituitarism secondary to ischemic injury and pituitary axonal tract damage. Athletes in contact sports may be at risk for pituitary insufficiencies or erectile dysfunction (ED) because of the high number of head traumas experienced during their careers. Whether multiple symptomatic concussive events are associated with later indicators of low testosterone levels and ED is unknown.

Objective  To explore the associations between concussion symptom history and participant-reported indicators of low testosterone levels and ED.

Design, Setting, and Participants  This cross-sectional study of former professional US-style football players was conducted in Boston, Massachusetts, from January 2015 to March 2017. Surveys on past football exposures, demographic factors, and current health conditions were sent via electronic and postal mail to participants within and outside of the United States. Analyses were conducted in Boston, Massachusetts; the data analysis began in March 2018 and additional analyses were performed through June 2019. Of the 13 720 male former players eligible to enroll who were contacted, 3506 (25.6%) responded.

Exposures  Concussion symptom score was calculated by summing the frequency with which participants reported 10 symptoms, such as loss of consciousness, disorientation, nausea, memory problems, and dizziness, at the time of football-related head injury.

Main Outcomes and Measures  Self-reported recommendations or prescriptions for low testosterone or ED medication served as indicators for testosterone insufficiency and ED.

Results  In 3409 former players (mean [SD] age, 52.5 [14.1] years), the prevalence of indicators of low testosterone levels and ED was 18.3% and 22.7%, respectively. The odds of reporting low testosterone levels or ED indicators were elevated for previously established risk factors (eg, diabetes, sleep apnea, and mood disorders). Models adjusted for demographic characteristics, football exposures, and current health factors showed a significant monotonically increasing association of concussion symptom score with the odds of reporting the low testosterone indicator (highest vs lowest quartile, odds ratio, 2.39; 95% CI, 1.79-3.19; P < .001). The ED indicator showed a similar association (highest quartile vs lowest, odds ratio, 1.72; 95% CI, 1.30-2.27; P < .001).

Conclusions and Relevance  Concussion symptoms at the time of injury among former football players were associated with current participant-reported low testosterone levels and ED indicators. These findings suggest that men with a history of head injury may benefit from discussions with their health care clinicians regarding testosterone deficiency and sexual dysfunction.

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Article Information

Accepted for Publication: June 21, 2019.

Corresponding Author: Rachel Grashow, PhD, MS, Department of Environmental Health, Harvard T. H. Chan School of Public Health, 655 Huntington Ave, Bldg 1, Ste 1402, Boston, MA 02215 (

Published Online: August 26, 2019. doi:10.1001/jamaneurol.2019.2664

Open Access: This is an open access article distributed under the terms of the CC-BY License. © 2019 Grashow R et al. JAMA Neurology.

Author Contributions: Dr Grashow had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Concept and design: Grashow, Weisskopf, Miller, Nathan, Zafonte, Speizer, Pascal-Leone, Roberts.

Acquisition, analysis, or interpretation of data: Grashow, Weisskopf, Miller, Zafonte, Speizer, Courtney, Baggish, Taylor, Pascal-Leone, Nadler, Roberts.

Drafting of the manuscript: Grashow, Miller, Zafonte, Baggish, Roberts.

Critical revision of the manuscript for important intellectual content: All authors.

Statistical analysis: Grashow, Weisskopf, Roberts.

Obtained funding: Zafonte, Courtney, Taylor, Pascal-Leone.

Administrative, technical, or material support: Grashow, Nathan, Courtney, Taylor, Pascal-Leone.

Supervision: Weisskopf, Miller, Nathan, Zafonte, Baggish, Pascal-Leone, Nadler, Roberts.

Other - design of data collection instruments and supervision of data acquisition: Speizer.

Conflict of Interest Disclosures: Drs Grashow, Miller, and Roberts reported grants from the NFL Players Association (NFLPA) during the conduct of the study. Dr Weisskopf reported grants from the NFLPA during the conduct of the study and personal fees from Partners Health Care. Dr Zafonte reported receiving royalties from Oakstone and Demos (serving as coeditor of the text Brain Injury Medicine) and serves on the scientific advisory boards of Oxeia Biopharma, Biodirection, ElMINDA, and Myomo. He was partially supported by grants from the National Institute on Disability, Independent Living, and Rehabilitation Research (90DP0039-03-00, 90SI5007-02-04, 90DP0060); US Army Medical Research & Development Command (W81XWH-112-0210); the National Institutes of Health (4 U01NS086090-04, 5R24HD082302-02, and 5U01NS091951-03), and the Football Players Health Study at Harvard University, which is funded by the NFLPA. Dr Zafonte also evaluates patients for the MGH Brain and Body TRUST center sponsored in part by the NFLPA and serves on the Mackey White health committee. Dr Courtney reported grant support from the NFLPA and the Football Players Health Study at Harvard University, which was in turn sponsored by the NFLPA during the development, submission and revision of the manuscript. Dr Baggish reported receiving funding from the National Institutes of Health/National Heart, Lung, and Blood Institute, the NFLPA, the American Heart Association, the American Society of Echocardiography, and the US Department of Defense. He serves as an associate editor for Medicine Science in Sports & Exercise and is on the editorial board for Circulation. He receives compensation for his role as team cardiologist from US Soccer, US Rowing, the New England Patriots, the Boston Bruins, the New England Revolution, and Harvard University. Dr Pascal-Leone reported personal fees from Neosync, Neuroelectrics, Starlab, Constant Therapy, and Cognito outside the submitted work. He serves as associate editor for Annals of Neurology. No other disclosures were reported.

Funding/Support: This study was partly supported by the Sidney R. Baer Jr Foundation, the National Institutes of Health (grants R01MH100186, R21AG051846, R01MH111875, R01MH115949, R01 MH117063, R24AG06142, and P01 AG031720), the National Science Foundation, DARPA, the Football Players Health Study at Harvard University, and Harvard Catalyst/The Harvard Clinical and Translational Science Center (National Center for Research Resources and the National Center for Advancing Translational Studies National Institutes of Health grant UL1 RR025758; Dr Pascual Leone) as well as the NFLPA.

Role of the Funder/Sponsor: The NFLPA had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

Disclaimer: All of the information and materials in this manuscript are original.

Additional Contributions: We thank the study participants, advisors, and staff of the Football Players Health Study. The staff received compensation for their contributions.

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