July 7, 2021 -- Gray hair, jokingly referred to as stress highlights, is a visible sign of aging that has long been tied to personal pressure, but the theory is difficult to prove. Now, researchers say they can measure what is happening when hair grays, and provide early evidence that it can sometimes be reversed.
Before hairs emerge from the scalp, they grow under the skin in follicles that receive chemical and electrical signals, including stress hormones, from the body. Once they emerge, hairs harden, and their molecular structure is preserved and reflected in their pigment.
Using high-resolution scanners, scientists can now detect small color changes in single strands of human hair.
Researchers measured color loss in single strands of human hair from 14 volunteers who kept diaries to document their weekly levels of stress. The results were striking: As the volunteers had more stress, their hair lost pigment. But as the stress eased, their hair regained color, says Martin Picard, PhD, an associate professor of behavioral medicine at Columbia University Vagelos College of Physicians and Surgeons in New York City, who led the research.
Researchers used a method to capture images of hair fragments so tiny, they represent 1 hour's growth. The technique, which allowed the researchers to assess pigment loss, was developed by Ayelet Rosenberg, a research assistant in Picard's laboratory, who is first author on the study.
And when hair color changed, the team saw variations in 300 proteins.
They developed a mathematical model to predict what might happen to human hair over time and suggest there is a point in a person's life when stress can temporarily induce loss of color, but that can be reversed if tensions ease.
These findings add to a growing body of evidence showing that aging is not a linear, fixed biologic process; it can be halted or even temporarily reversed.
With a better understanding of the biologic basis of pigment loss, it's possible that gray hair could one day be reversed with a visit to the doctor's office instead of the hair salon.
The research was funded by grants from the Wharton Fund and the National Institutes of Health.