The Psychology of Gray Hair

The study by Zhang et al. (2020) provided evidence for the long-held belief that stress can lead to hair graying. They demonstrated that stress induces the release of noradrenaline from sympathetic nerves, which depletes melanocyte stem cells (MeSCs) in hair follicles, responsible for hair pigmentation. The researchers used black-coated C57BL/6J mice and subjected them to various stressors, finding that pain was the most potent in causing hair graying. They showed that stress did not affect differentiated melanocytes but significantly reduced the number of MeSCs. By modulating sympathetic nerve activity, they confirmed that noradrenaline release was necessary and sufficient for MeSC depletion. Pharmacological and genetic interventions that suppressed MeSC proliferation preserved hair pigmentation under stress, supporting the hypothesis that stress-induced noradrenaline release leads to MeSC depletion and hair graying. This study not only explains how stress can cause hair to gray but also opens up questions about the role of MeSCs in human skin and potential treatments for pigmentation disorders and cancer.