Graying of hair is related to psychological stress but may be reversible.

www.scientificamerican.com

The loss of hair pigmentation (graying) is a hallmark of aging. Although it typically begins during a person’s twenties, the timing and extent of graying vary according to genetics and interactions between biological and psychological factors. Graying is generally considered irreversible, but findings from a recent study demonstrate that graying is not necessarily a linear process and may be reversible.

One of the primary drivers of graying is oxidative stress, which damages the pigment-producing region of the hair shaft. Oxidative stress occurs during the process of oxidative phosphorylation (the generation of energy) in mitochondria and can be reflective of exposures to both physical and psychological stressors. Evidence suggests that depigmented hairs may exhibit altered mitochondrial energy metabolism. Interestingly, case and anecdotal reports suggest that hair re-pigmentation can occur, causing bicolor hairs.

The authors of the study collected dark, depigmented, and bicolor hairs from 14 healthy young adults (average age, 35 years) who did not color, bleach, or chemically treat their hair. The authors digitally mapped pigmentation patterns in the hairs over time and assessed protein content in the hair shafts. Some of the participants completed a retrospective stress assessment questionnaire using a life event calendar, in which they recorded major events over a given time. Then the authors overlaid the hair pigmentation patterns on the participants' life events.

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The authors found that depigmentation and re-pigmentation events corresponded with specific moments in the participants' lives, with depigmentation linked to stressful events (such as marital discord) and re-pigmentation linked with non-stressful events (such as a vacation). The authors also found that depigmented hairs contained more proteins linked to mitochondrial function and energy use, suggesting that mitochondria and metabolism are involved in the graying process.

These findings suggest that graying of hair is a more malleable process than once thought and indicate that studying changes in hair color may provide insights into how psychological stressors influence health.