- Stress can trigger the flight or fi
ght response of the body and cause the pigment-producing cells to dwindle
- Signaling from the sympathetic nervous system, which plays a role in the body’s fight or flight response, is linked to stress-induced graying of hair
- The body does not replenish pigment-producing stem cells, so when they dwindle, it depletes the hair’s reservoir of color
Former US President Barack Obama previously blamed stress for his graying hair. A new study now shows that stress can indeed turn the hair gray.
In a new study, researchers found that stress can trigger the flight or fi
ght response of the body and cause the pigment producing cells responsible for giving hair its color to dwindle. The declining number of the pigment cells then causes the hair’s natural color to disappear.
For the study, stem cell biologist Ya-Chieh Hsu, from Harvard University and colleagues, stressed mice by injecting them with a compound closely related to capsaicin, which is naturally found in chili peppers.
They observed that within five days, the rodents’ hair turned white. When they eliminated other factors such as the stress hormone cortisol for the graying of the hair, the researchers found that signaling from the sympathetic nervous system, which plays a role in the body’s fight or flight response, is linked to stress-induced graying.
The sympathetic nerves release chemicals known as norepinephrine in response to stress, and this causes pigment producing stem cells to activate prematurely.
The body does not replenish stem cells so when the norepinephrine overactivates the reservoir of pigment-producing stem cells, it causes the latter to activate prematurely. This rapidly uses up the stem cell supply, which in turn depletes the hair’s reservoir of color.
“When we started to study this, I expected that stress was bad for the body — but the detrimental impact of stress that we discovered was beyond what I imagined,” Hsu said. “After just a few days, all of the melanocyte stem cells were lost. Once they’re gone, you can’t regenerate pigments anymore. The damage is permanent.”
The findings of the new study were published in the journal Nature on Jan. 22.