By Phillip Schneider | Waking Times
Is it true that stress can cause our hair to turn gray? For decades, scientists could not figure out how this happens, often theorizing that stress hormones such as cortisol must play some role in the process.
However, researchers have finally discovered where graying comes from, and the answer lies in hair cells called melanocytes. Melanocytes are a type of cell that determine the amount of melanin in a given hair follicle. These cells define our hair color and are derived from melanocyte stem cells (MeSC), which are located in a part of each hair called the bulge.
As we age, the number of MeSC’s gradually deplete, leaving us with increasingly less color until all MeSC’s are gone, turning our hair completely gray, then white. There are other ways our hair can turn gray besides aging, including malnutrition, disorders like vitiligo, but the most common reason is stress.
In a study published by the journal Nature, Bing Zhang, et al. discovered that our sympathetic nervous system (SNS), which is responsible for the “fight-or-flight” mechanism, is the key to understanding how stress causes our hair to cahnge color.
As the SNS releases high amounts of noradrenaline in response to stress, the hormone agitates MeSC cells, accelerating their depletion. In contrast, suppression of noradrenaline from the SNS of mice prevented whitening under stress.
“Here we report that, in mice, acute stress leads to hair greying through the fast depletion of melanocyte stem cells…hair greying results from activation of the sympathetic nerves that innervate the melanocyte stem-cell niche.” – Bing Zhang, et al.
Unfortunately, after all MeSC’s have depleted from a hair follicle, they never come back. “And once they’re gone, pigment cannot be generated anymore,” says Ya-Chieh Hsu, a professor of stem cell and regenerative biology at Harvard.
Now that we understand what causes our hair to turn gray, it’s likely that companies will jump on this discovery in an attempt to sell products that claim to prevent hair graying.
