Rachel Grashow PhD Research Associate Department of Environmental Health Football Players Health Study at Harvard University Harvard T.H. Chan

Concussions Linked to Risk of Low Testosterone and Erectile Dysfunction

MedicalResearch.com Interview with:

Rachel Grashow PhD Research Associate Department of Environmental Health Football Players Health Study at Harvard University Harvard T.H. Chan

Dr. Grashow

Rachel Grashow PhD
Research Associate
Department of Environmental Health
Football Players Health Study at Harvard University
Harvard T.H. Chan 

MedicalResearch.com: What is the background for this study?

Response: It has been previously shown in small studies of boxers and military personnel that traumatic brain injuries can damage the pituitary gland, which serves as the “master controller” of hormone function in the brain. These studies on individuals at risk for repeated head injury found that hits on the head caused deficiencies in certain hormones, such as growth hormone and testosterone, which could have downstream effects on sexual function. Only one large study was conducted that used Taiwanese health insurance data and looked at single traumatic brain injuries and risk of erectile function (ED). In that study, men who experienced a single severe TBI were more than twice as like to report ED after their injury. In light of these findings, important questions remain regarding whether multiple head injuries are associated with pituitary or sexual dysfunction in a large population with other ED-related health issues. The Football Players Health Study at Harvard University asked former NFL players to fill out a questionnaire that interrogated demographic factors, football-related exposures and current health conditions. Specifically, we asked participants to self-report the frequency of ten different concussion symptoms experienced during professional play, as well as whether a clinician had ever recommended or prescribed medication for low testosterone or ED.  

MedicalResearch.com: What are the main findings?

Response: We found  that men who reported the highest number of concussion symptoms were two and a half times more likely to report receiving either a recommendation for medication or to be currently taking medication for low testosterone, compared to men who reported the fewest concussion symptoms. Men with the most concussion symptoms were nearly two times more likely to report receiving a recommendation to take ED medication or to be currently taking ED medication than those reporting the fewest symptoms. Players who reported losing consciousness following head injury had an elevated risk for ED even in the absence of other concussion-related symptoms. Interestingly, even former players with relatively few concussion symptoms had an elevated risk for low testosterone, suggesting that there may be no safe threshold for head trauma. 

MedicalResearch.com: What should readers take away from your report?

Response: We are hoping that these findings motivate clinicians to speak openly about sexual function with their brain-injured patients, since previous studies have shown that even a single head injury may result in sexual dysfunction symptoms. Furthermore, we are hoping that these results encourage former football players and others with repeated head injuries to speak to their doctors about any low testosterone or ED symptoms they are experiencing. ED can also be a sign of systemic illness, so we encourage any man experiencing ED to speak to their healthcare provider.

MedicalResearch.com: What recommendations do you have for future research as a result of this work? 

Response: We need longitudinal studies that follow individuals exposed to head trauma over time to better understand the relationship between head injury and hormone insufficiencies and erectile dysfunction. We hope that studies on hormonal dysfunction can also be conducted on female athletes, as well as hockey players, soccer players and others.   

MedicalResearch.com: Is there anything else you would like to add? 

Response: We are grateful to the Football Players Health Study participants and staff for all their help on this project.


All  authors named on this study are or were either partially or fully supported by the Football Players Health Study at Harvard University which is in turn sponsored by the NFL Players Association. Please note that 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. Other authors report no potential or actual conflicts of interest. 


Grashow R, Weisskopf MG, Miller KK, et al. Association of Concussion Symptoms With Testosterone Levels and Erectile Dysfunction in Former Professional US-Style Football Players. JAMA Neurol. Published online August 26, 2019. doi:10.1001/jamaneurol.2019.2664


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Last Updated on August 26, 2019 by Marie Benz MD FAAD