Age-related graying of the hair — a brief summary of potential mechanisms

Graying of the hair is one of the most eye-catching phenotypic changes related to the chronological aging. During the last decades, scientists have engaged in research that has increased our understanding of different mechanisms of aging of a hair follicle, however many aspects of this process remain unclear. Progressive hypopigmentation of the hair shaft has been associated with decrease in number of melanocytes and tyrosinase hypoactivity in the hair bulb along with the depletion of melanocyte stem cells (MSCs) in the bulge area. Pathogenesis of graying may involve oxidative damage and incompetent MSCs maintenance. Moreover, other factors such as defective melanosomal transfer as well as insufficient neuroendocrine stimulation of MSCs and melanogenesis are hypothesized to play an important role.