Concussion symptoms at the time of injury among football players may increase the risk of low testosterone levels and erectile dysfunction (ED), a cross-sectional study of former professional football players suggests.

The study included 3409 participants in the Football Players’ Health Study who played for the National Football League (NFL) after 1960. The prevalence of indicators of low testosterone and ED (a self-reported history of a medical provider’s recommendation or prescription for medications to treat these conditions) was 18.3% and 22.7%, respectively. The risk of having indicators of low testosterone and ED increased with each successive quartile of concussion symptom score. Compared with players in the first quartile (reference), those in the second, third, and fourth quartiles had significant 1.4-, 1.5-, and 2.4-fold increased odds of low testosterone levels, respectively, and 1.3-, 1.6-, and 1.9-fold increased odds of ED, respectively, in fully adjusted models.

“This study’s data suggest that concussion symptoms experienced during playing years may place NFL players at risk of low testosterone levels and ED decades later,” a team led by Rachel Grashow, PhD, MS, of the Harvard T.H. Chan School of Public Health in Boston, concluded in a paper published in JAMA Neurology. “These findings have implications for civilians and veterans who have experienced head injury, as well as for participants in combative and contact sports (eg, mixed martial arts, hockey, boxing, and soccer) who may experience repeated head trauma.”

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For the study, participants were asked, “While playing or practicing football, did you experience a blow to the head, neck, or upper body followed by any of the following: headaches, nausea, dizziness, loss of consciousness, memory problems, disorientation, confusion, seizure, visual problems, or feeling unsteady on your feet?” Response options were: none, once, 2 to 5 times, 6 to 10 times, or 11 times or more for each symptom. Respondents also were asked if a medical provider ever recommended or prescribed medication for low testosterone or ED. An affirmative answer served as an indicator of a history of low testosterone or ED, respectively. Investigators created concussion symptom scores by coding concussion symptom frequency responses of none, once, 2 to 5 times, 6 to 10 times, or 11 or more times as 0, 1, 3.5, 8, and 13, respectively, and then adding the numbers to arrive at a sum.

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Trauma-induced pituitary damage is among the hypothesized mechanisms that could explain the link between concussions and low testosterone and ED. The authors explained that the pituitary gland is perfused by long portal vessels branching off the internal carotid artery and, therefore, is susceptible to mechanical trauma, low cerebral blood flow, and increased intracranial pressure associated with head injury. “Acceleration and deceleration forces can shear axonal tracts that connect the pituitary to the hypothalamus,” Dr Grashow’s team wrote. “Thus, the combination of intracranial pressure, reduced blood flow, and diffuse axonal injury between the pituitary and the hypothalamus could cause diminished pituitary function, leading to low testosterone levels and ED.”


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 [published online August 26, 2019]. JAMA Neurol. doi:10.1001/jamaneurol.2019.2664