Science has proven what we’ve known anecdotally for years—stress does indeed cause premature hair-graying. When we see a silver strand sprout up, it's easy to blame the kids, your spouse, your career, or the state of the world. Thanks to a study entitled Hyperactivation of sympathetic nerves drives depletion of melanocyte stem cells, those accusations finally have merit.

Hair follicles contain pigment cells that make melanin called melanocytes which determine the natural color of our hair. Over time, they stop doing their job, leading canities. Pronounced kenishees, canities is the medical term for hair-graying, or rather "the diminishing of pigment in hair producing a range of colors from normal to white that is perceived as gray."

Age, genes, and environmental factors such as stress all play a part in determining when our melanocytes stop producing color. Every decade after 30, your chances of going gray increase by 10-20%. Mom and Dad also play a part—scientists have discovered that the IRF4 gene variant accounts for about 30 percent of gray hair. According to the Library of Congress, "genes regulate the exhaustion of the pigmentary potential of each individual hair follicle. This occurs at different rates in different hair follicles. For some people it occurs rapidly, while in others it occurs slowly over several decades." Now, in the first scientific link between stress and hair graying, researchers from the Universities of Sao Paulo and Harvard found that stressful events can be responsible for damaging pigment-producing stem cells.

A new study led by postdoctoral fellow Bing Zhang used mice to connect the dots between stress, fight or flight, stem-cell depletion, and premature graying. Hsu and her colleagues exposed to three types of stress involving mild, short-term pain, psychological stress, and restricted movement. For instance, they injected mice with a capsaicin-like compound, which is the active ingredient in chili peppers. The results? The rodents’ fur turned white within five days’ time. As the BBC explains, “Pain in mice triggered the release of adrenaline and cortisol, making their hearts beat faster and blood pressure rise, affecting the nervous system and causing acute stress.”

So how could the scientists know what exactly was causing the rodents sudden Marie Antoinette syndrome? As Science News reports, “After eliminating the immune system and the stress hormone cortisol as causes of the color change, the team discovered that part of the animals’ nervous system was depleting pigment cells from hair.”

Stress triggers the body’s fight-or-flight response, which is driven by the sympathetic nervous system. According to livescience.com, the body quickly and involuntary responds to dangerous or stressful situations by increasing your “blood pressure, breathing rate, and hormone flow.” Sympathetic nerves branch out into each hair follicle. Stress triggers the activation of these sympathetic nerves, which according to the study, leads to a burst release of the neurotransmitter noradrenaline. Also known as norepinephrine, noradrenaline causes the stem cells to activate excessively. As BBC observes, stressing the mice out "sped up the depletion of stem cells that produced melanin in hair follicles."

In other words, pigment-producing cells plummet. No pigment cells mean no color. “Stress makes the stem cells differentiate faster, exhausting their number and resulting in strands that are more likely to be transparentgray," according to the New York Times.

The damage is permanent. Dr. Zhang points out that “Acute stress, particularly the fight-or-flight response, has been traditionally viewed to be beneficial for an animal’s survival. But in this case, acute stress causes permanent depletion of stem cells.” As Science News says, “The body can’t replenish the stem cells, so as these cells are used up, color vanishes.”

Stress leads to many reactions we can’t see, including high blood pressure, heart attacks, anxiety, and depression. But this study opens the door to investigating how our tissues and stem cells change under stress. Learning more could eventually lead researches to “create treatments that can halt or reverse its detrimental impact,” Dr. Hsu said. Someday, we may even be able to modify or block the damaging effects of stress, like gray hairs!

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