“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,” said senior author Martin Picard, Ph.D., associate professor of behavioral medicine at Columbia. “Our data 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.”
“When hairs are still under the skin as follicles, they are subject to the influence of stress hormones and other things happening in our mind and body. Once hairs grow out of the scalp, they harden and permanently crystallize these exposures into a stable form,” Picard said.
First author Ayelet Rosenberg developed a new method for capturing highly detailed images of small slices of human hairs. This quantifies the extent of graying in each slice.
“If you use your eyes to look at a hair, it will seem like it’s the same color throughout unless there is a major transition,” Picard said. “Under a high-resolution scanner, you see small, subtle variations in color, and that’s what we’re measuring.”
Researchers evaluated hairs from 14 volunteers. They were asked to rate their weekly stress level in a diary. Scientists compared hair results to the participant’s diary. When researchers aligned stress hairs with the diary, they noticed a connection to stress and graying hair. Some cases showed graying reversed with stress lifting. Scientists observed some gray hairs naturally regained their original color.
“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,” Picard said.
But not everyone will regain their original hair color.
“Based on our mathematical modeling, we think hair needs to reach a threshold before it turns gray,” Picard said. “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.
“But we don’t think that reducing stress in a 70-year-old who’s been gray for years will darken their hair or increasing stress in a 10-year-old will be enough to tip their hair over the gray threshold.”
Kiersten Willis is a Georgia-born native specialist for the revenue content team with The Atlanta Journal-Constitution. Responsible for helping to fulfill sponsorships, she also works on advertorial content and manages the Aging in Atlanta special print section. She's a graduate of the University of Georgia.