How stress causes gray hair

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FOR a long time, anecdotes have connected stressful experiences with the phenomenon of hair graying. Now, for the first time, Harvard University scientists have discovered exactly how the process plays out: stress activates nerves that are part of the fight-or-flight response, which in turn cause permanent damage to pigment-regenerating stem cells in hair follicles.

The study, published in Nature, advances scientists’ knowledge of how stress can impact the body.

To connect stress with hair graying, the researchers started with a whole-body response and progressively zoomed into individual organ systems, cell-to-cell interaction and, eventually, all the way down to molecular dynamics. The process required a variety of research tools along the way, including methods to manipulate organs, nerves, and cell receptors.

“We know that peripheral neurons powerfully regulate organ function, blood vessels, and immunity, but less is known about how they regulate stem cells,” said Isaac Chiu, assistant professor of immunology at Harvard Medical School.

“With this study, we now know that neurons can control stem cells and their function, and can explain how they interact at the cellular and molecular level to link stress with hair graying.”

The findings can help illuminate the broader effects of stress on various organs and tissues. This understanding will pave the way for new studies that seek to modify or block the damaging effects of stress.

“By understanding precisely how stress affects stem cells that regenerate pigment, we’ve laid the groundwork for understanding how stress affects other tissues and organs in the body,” Hsu said. “Understanding how our tissues change under stress is the first critical step towards eventual treatment that can halt or revert the detrimental impact of stress. We still have a lot to learn in this area.”