In a new study from Columbia University, researchers found quantitative evidence linking psychological stress to graying hair in people.
And while it may seem intuitive that stress can accelerate graying, the researchers were surprised to discover that hair color can be restored when stress is eliminated.
They say that understanding the mechanisms that allow ‘old’ 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 findings add to a growing body of evidence demonstrating that human aging is not a linear, fixed biological process, but may, at least in part, be halted or even temporarily reversed.
Though people have long believed that psychological stress can accelerate gray hair, scientists have debated the connection due to the lack of sensitive methods.
In the study, the team developed a new method for capturing highly detailed images of tiny slices of human hairs to quantify the extent of pigment loss (graying) in each of those slices.
They analyzed individual hairs from 14 volunteers. The results were compared with each volunteer’s stress diary, in which individuals were asked to review their calendars and rate each week’s level of stress.
The team immediately noticed that some gray hairs naturally regain their original color.
When hairs were aligned with stress diaries, striking associations between stress and hair graying were revealed, and in some cases, a reversal of graying with the lifting of stress.
For example, there was one individual who went on vacation, and five hairs on that person’s head reverted back to dark during the vacation, synchronized in time.
To better understand how stress causes gray hair, the researchers also measured levels of thousands of proteins in the hairs and how protein levels changed over the length of each hair.
They found stress-induced changes in mitochondria (the powerhouses of the cell) may explain how stress turns hair gray.
Based on the team’s mathematical modeling, they think hair needs to reach a threshold before it turns gray. In middle age, when the hair is near that threshold because of biological age and other factors, stress will push it over the threshold and it transitions to gray.
For more information about hair health, please see recent studies about a new method to make hair regrow and results showing that scientists discover drug that could treat hair loss effectively.
The study is published in eLife. One author of the study is Martin Picard, Ph.D.
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