What is associated with the appearance of "stress" gray hair?

It turns out that stressful nerve impulses cause depletion of the resources of stem cells involved in the formation of pigment hair structures.

It is known that with a strong fright or nervous shock, hair can quickly turn gray. But how is this possible and why does it happen?

Often, people who are often nervous and worried go gray faster than others. But it is not always clear where to look for the root cause of early graying - in stress, age-related changes, diseases or hereditary predisposition.

Through a series of studies, scientists from Harvard University have proven that stress alone is enough to cause early graying. Hair color depends on the number of melanocyte cells, which accumulate the pigment melanin. The melanocytes themselves are formed from certain stem cells that are localized directly in the hair follicle. In young people, they are periodically renewed, but over the years their number decreases, and the hair gradually turns gray.

Through experiments with rodents, scientists were able to discover that such regular irritants as pain, being pinched in something, and difficult psychological situations lead to a decrease in the number of stem cells in the follicle and, as a consequence, to the appearance of gray hair.

Initially, it was assumed that the hair follicle is exposed to the stress hormone corticosterone. There was another theory: the body's immune defense mistakenly attacks the corresponding stem cells under stress. However, it turned out that there is another main reason. The fact is that melanocyte stem cells have endings sensitive to norepinephrine, which is involved in the stress mechanism. Thus, it helps create neural circuits that "decide" what the reaction to stress will be. When such receptors were "switched off", stress-related graying of hair ceased in rodents.

But what is the purpose of gray hair due to stress? Experts explain that for many animals – for example, monkeys – gray hair is a sign of maturity, experience and strength. This means that, for example, a gray male is always more respected and can even lead a pack. However, this is just an assumption, and it is quite possible that gray hair does not carry any evolutionary load.

Presumably, melanocyte stem cells are not the only structures that react to stress. Similar processes are observed with blood stem cells: as a result of the “shake-up”, they leave their zones in the bone marrow and stop renewing. Perhaps frequent or severe stress has a negative effect on other types of stem cells as well. This could explain a lot – for example, why the immune defense weakens against the background of stress, and age-related changes occur faster.

The information is presented on the pages of the Nature publication