Stress turns hair gray by triggering the body’s fight-or-flight response
It turns out stress does turn hair gray, and now researchers know how. Stress triggers the body’s fight-or-flight response, which in turn causes pigment-producing cells that give hair its color to go into a frenzy and dwindle in number, researchers report online January 22 in Nature. As these pigment cells disappear, so does the color. Gray hair has been linked to stress for centuries — think of U.S. presidents before and after holding office. But scientists didn’t understand how stress makes hair go gray. “It was satisfying to question a popular assumption … [and] to identify the mechanisms that now open up new areas of work,” says Ya-Chieh Hsu, a stem cell biologist at Harvard University. Hsu and her colleagues stressed mice by injecting them with a compound closely related to capsaicin, the active ingredient in chili peppers. Within five days, the rodents’ hair turned white. After eliminating the immune system and the...