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The Science of How Getting Hit in the Head Stops Your Dick From Working

Scientists recently uncovered a link between concussion and erectile dysfunction — and they’ve got some theories as to why it happens

To many, professional football players are the ultimate example of male virility — strong, athletic, powerful and just plain manly. But as it turns out, they could be quietly dealing with yet another side effect from the multiple concussions they’ve received that, um, softens this image somewhat: Their dicks might not work.

According to a Harvard Medical School study published last month, football players who had experienced concussive symptoms after a head injury were more likely to experience erectile dysfunction or low testosterone. The study doesn’t conclusively state that head injuries are a cause of erectile dysfunction, nor does it explain exactly why the statistical correlation exists; however, even when accounting for variables that can typically contribute to ED (age, heart disease, depression, etc.) the statistical correlation remained. 

“There have been a few studies published on ED and head trauma that hinted to us that we might find a connection between the two in our population of former football players,” says Rachel Grashow, a research scientist with the Football Players Health Study at Harvard University and the lead author of the study. “First, a few small studies in boxers and military men had shown that repeated head trauma led to the types of hormone dysfunction that can lead to ED. But these studies were small, with only about 40 men in each.” 

This new study, which surveyed more than 3,400 former NFL players, is the first to look at the effects of multiple head traumas among a larger group. “That’s important because you need a lot of participants to adequately control for all the other reasons a man might report ED. So we could say, even if we take all these other ED causes into account, do we still see a link between head injuries and ED or low testosterone? And in our case, the answer was yes,” explains Grashow. 

The large participant pool also allowed the researchers to measure whether the extent of head injuries correlated with the extent of ED symptoms experienced. Sure enough, they found that higher numbers of concussion symptoms resulted in higher risk of ED or low testosterone. 

Despite not publishing a conclusive answer as to why this link exists, Grashow and her team do have a possible theory. “We believe that the underlying biological mechanism that accounts for our results is called ‘post-traumatic hypopituitarism,’” she says. “The pituitary gland is the ‘master hormone controller’ in the brain. It’s shaped like a bulb — actually a lot like a testicle! — and it hangs down in the middle of the brain. It’s connected to the rest of the brain by thin tissue that contains blood vessels and neurons that communicate with the rest of the brain. This anatomy makes the pituitary very susceptible to head hits.” 

In simpler terms, because head trauma results in damaged blood vessels and neuronal connections, the pituitary gland’s blood supply is reduced. The gland then can’t initiate the reactions necessary to produce testosterone, and without that, you can’t have proper erectile function. 

But is this only likely to be a problem for the pros, or is it something that should worry the average guy who only plays football on Thanksgiving, too? According to a previous study of Taiwanese men’s erectile function following a single head injury, one bad concussion (resulting in a hospital visit) can indeed impair your sexual health. And according to Grashow, the more head trauma a man experiences, the more likely he is to have ED. 

Grashow admits that more research still needs to be done, but she hopes her recent study could open the door to it. “We know that hockey players, boxers, mixed martial artists and soccer players all can experience head injuries during their careers,” she says. “It’s my hope that if elite athletes experiencing sexual dysfunction are able to tie their symptoms to their activity on the field, as opposed to a personal failure or reflection of their masculinity, that they will be more likely to speak to their doctors about these very treatable conditions.” 

It’s also worth pointing out that for guys who aren’t being tackled for a living, ED is likely a sign of more serious problems than low testosterone. Not only can ED be the result of mental health issues like anxiety and depression, it’s often linked to cardiovascular disease and diabetes. So seeking treatment for erectile dysfunction isn’t just a matter of keeping your dick working — it’s a matter of keeping those more trivial organs like your heart functional, too.