We have heard of stories like Marie Antoniette where stress caused an almost instant graying of hair. But the science behind this phenomenon was still unclear. A recent study by Harvard University may have finally shed some light on this occurrence. According to an animal study, published in the journal Nature, stress activates certain nerves that cause permanent damage to the pigment-carrying cells in hair follicles.
Since stress affects the whole body, the scientists had to narrow down the system responsible for this occurrence. The initial hypothesis was that stress affects the immune system, spiking cortisol levels which attack the pigment cells. To test this, the team removed the adrenal glad which produced the cortisol hormone. However, this made no difference. The team eliminated different probabilities in the same manner until they narrowed down to the sympathetic nervous system.
Further experiments revealed that the sympathetic nerves release the chemical norepinephrine, which affects the pigment-regenerating stem cells in the hair follicles. The stem cells go into overdrive, depleting the reservoir of pigment. With continued stress, the pigment-regenerating cells were lost permanently.