It seems that people have known for a long time, and research has suggested that stress can cause hair to turn gray. Now scientists have confirmed that psychological stress can promote the growth of gray hair. Contrary to other recent research, the work also indicated that this change may be reversible if the stress is eliminated. These findings have been reported in eLife.
In this study, this investigation assessed hair samples from fourteen volunteers, who reviewed their calendars and rated stress levels each week. First study author Ayelet Rosenberg developed a technique for quantifying how much gray there was in tiny slices of the hair samples.
"Just as the rings in a tree trunk hold information about past decades in the life of a tree, our hair contains information about our biological history," explained senior study author Martin Picard, Ph.D., an associate professor of behavioral medicine at Columbia University Vagelos College of Physicians and Surgeons. "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."
The scientists found that some gray hairs regained their original color. The team used the self-reported volunteer data to reveal links between stress ratings and hair graying. In some cases, graying reversed as stress was relieved.
"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. Under a high-resolution scanner, you see small, subtle variations in color, and that's what we're measuring," said Picard.
"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," he noted.
The study authors suggested that we may gain some insight into how stress affects aging on a physiological level from this research, and that it may be possible to halt or maybe reverse aging in some cases.
The researchers also analyzed the levels of proteins in through the length of various hairs. They found that as hair color changed, there were alterations in the levels of 300 different proteins, and made a model that could explain how stress induced mitochondrial changes that could explain graying hair.
"We often hear that the mitochondria are the powerhouses of the cell, but that's not the only role they play," Picard said. "Mitochondria are actually like little antennas inside the cell that respond to a number of different signals, including psychological stress."
Picard suggested that their models indicated that there is some threshold hair has to reach before turning 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," said Picard. "But we don't think that reducing stress in a seventy-year-old who's been gray for years will darken their hair or increasing stress in a ten-year-old will be enough to tip their hair over the gray threshold."