Those annoying grey hair that tend to crop up with age really are signs of stress, according to a new study. The research, published in the journal Nature, found that stress activates nerves that are part of the fight-or-flight response, which in turn cause permanent damage to pigment-regenerating stem cells in hair follicles.
Sympathetic nerves branch out into each hair follicle on the skin. The researchers found that stress causes these nerves to release the chemical norepinephrine, which gets taken up by nearby pigment-regenerating stem cells.In the hair follicle, certain stem cells act as a reservoir of pigment-producing cells.
When hair regenerates, some of the stem cells convert into pigment-producing cells that colour the hair.Researchers found that the norepinephrine from sympathetic nerves causes the stem cells to activate excessively. The stem cells all convert into pigment-producing cells, prematurely depleting the reservoir.