It is intuitive to think that stress can accelerate aging, what is surprising is that according to a recent study, hair color can be restored if stress is eliminated (Rosenberg et al., 2021).
The authors compare a person’s hair to the rings on the stem of a tree: just as these contain information about past decades in the life of a tree, hair contains information about a person’s biological history: when the hairs are still under the skin as follicles, they are subject to the influence of stress hormones and other things happening in the mind and body. Once hairs grow out of the scalp, they permanently crystallize these exposures into a stable form.
Because it is important?
Understanding the mechanisms that allow “aged” (gray) hairs to return to their “young” (pigmented) states could yield new clues about the malleability of human aging in general and how it is influenced by stress. The results of this research add to a growing body of evidence demonstrating that human aging is not a fixed and linear biological process, but can, at least in part, be stopped or even temporarily reversed.
Methodology
The researchers used a novel method of dividing hair to document its pigmentation and capturing highly detailed images of small cuts of human hair to quantify the degree of pigment loss (graying) in each portion (each slice, approximately 1/20 of a millimeter wide, represents approximately one hour of hair growth). By examining these portions under a high-resolution scanner it is possible to see and measure small, subtle color variations.
In the study, individual hairs of 14 volunteers were analyzed, who in turn kept stress diaries.
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Findings
The authors immediately noticed that some gray hairs naturally recovered their original color. This had never been quantitatively documented.
By aligning hair with stress diaries they found surprising associations between stress and hair graying and, in some cases, a reversal of graying with the cessation of stress.
To understand how stress causes gray hair, researchers also measured the levels of thousands of proteins in hairs and how they changed along the length of each hair.
Changes in 300 proteins occurred when hair color changed, and the researchers developed a mathematical model that suggests that stress-induced changes in mitochondria may explain how stress turns hair gray. They explained that mitochondria are like small antennas inside the cell that respond to a number of different signals, including psychological stress.
The mitochondrial connection between stress and hair color differs from that discovered in a recent study in mice, which found that stress-induced aging was caused by an irreversible loss of stem cells in the hair follicle. With this foundation, the authors understand that aging in people involves a different mechanism, and this may be a case where the findings in mice do not translate well to people.
Finally, they warn that while reducing stress is a good life goal, it won’t necessarily turn your hair from gray to your natural color. “We believe hair must reach a threshold before it turns gray. In middle age, when hair is close to that threshold due to biological age and other factors, stress will push it over the threshold and go gray. But we don’t believe that reducing stress in a 70-year-old who has had gray hair for years will darken her hair or that increasing stress in a 10-year-old girl will be enough to tip her hair over the gray threshold.”
Bibliographic reference: Rosenberg, AM, Rausser, S., Ren, J., Mosharov, EV, Sturm, G., Ogden, RT, Patel, P., Kumar Soni, R., Lacefield, C., Tobin, DJ, Paus, R. ., & Picard, M. (2021). Quantitative mapping of human hair graying and reversal in relation to life stress. eLife, 10. https://doi.org/
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