The appearance of grey hair is one of the clearest indicators of old age. Black, brown, blonde, or red strands lose their young color as we age. Even though this appears to be a permanent alteration, the current study suggests that the greying process can be reversed—at least briefly.
There have been rare case studies in the scientific literature that suggest grey hairs can spontaneously recover color. Stanley Comaish, the late dermatologist, recalled an interaction with a 38-year-old man who had a “very uncommon characteristic” in a 1972 article. Three strands were bright towards the ends but dark near the roots, even though the vast majority of the individual’s hairs were either all black or all white. This indicated a shift in the typical greying process, which starts at the root.
A group of researchers presented the most robust evidence of this occurrence to date in hair from about a dozen people of diverse ages, nationalities, and sexes in a paper published today in eLife. It also links greying and reversal patterns to times of stress, implying that this aging-related process is intimately linked to our psychological well-being.
According to research co-author Ralf Paus, a dermatologist at the University of Miami, these findings imply “that there is a window of opportunity within which greying is probably far more reversible than had been assumed for a long time.”
Martin Picard, a mitochondrial psychobiologist at Columbia University, began thinking about how our cells age in a multistep process, with some showing indications of aging far sooner than others, about four years ago. He saw that this patchwork process was apparent on our heads, where our hairs did not all turn grey at the same time. Picard adds, “It appeared like the hair, in some ways, recapitulated what we know happens at the cellular level.” “Perhaps there’s something there to learn. Perhaps the hairs that turn white first are the weakest or most vulnerable.”
Picard mentioned something in passing while discussing these ideas with his partner: if one could find a hair that was only partially gray—and then calculate how fast that hair was growing—it might be possible to pinpoint the time when the hair started aging and thus ask the question of what happened in the individual’s life to trigger this change. Picard remembers, “I was nearly thinking of this as a fictive idea.” However, his companion unexpectedly turned to him and stated she had seen similar two-colored hairs on her head. “She went to the restroom and plucked a couple,” he recalls, explaining how the effort began.
Picard and his colleagues started looking for additional people with two-colored hairs through classified advertising, social media, and word of mouth. They eventually found 14 persons, men, and women ranging in age from nine to 65, from diverse ethnic origins (although the majority were white). Those people contributed single- and two-colored hair strands from various body regions, including the scalp, face, and pubic area.
The researchers then devised a method for digitizing and quantifying the tiny color variations throughout each strand, which they called hair pigmentation patterns. Surprisingly, these patterns showed the following: Some greying hairs returned to color in ten of the subjects, who ranged in age from nine to 39. The researchers discovered that this happened not just on the head, but also in other parts of the body. Picard adds, “When we observed this in pubic hair, we thought, ‘OK, this is genuine.'” “Not only in one person or on the head, but across the entire body.” He goes on to say that the reversibility is likely confined to particular periods when alterations are still possible because they only showed in select hair follicles.
The majority of people see their first grey hairs in their 30s, while others may notice them as early as their late 20s. According to Paus, this era, when greying has just begun, is when the process is most reversible. Most strands of grey hair have probably reached a “point of no return” in people with a full head of grey hair, but certain hair follicles may still be flexible to change, he adds.
“What was most amazing was that they were able to show clearly that greying is truly reversible at the individual hair level,” says Matt Kaeberlein, a biogerontologist at the University of Washington who was one of the new paper’s editors but was not involved in the research. “What we’re finding is that biological changes that occur with age, not only in hair but in several tissues, are often reversible—this is a good illustration of that.”
The researchers also looked at the link between hair greying and psychological stress, since the previous study suggested that these factors might hasten the aging process of the hair. Anecdotes of such a link may be found throughout history: legend has it that the hair of Marie Antoinette, France’s 18th-century monarch, turned white overnight right before her guillotine death.
The researchers identified regions in single hairs where color alterations in pigmentation patterns occurred in a small group of individuals. Then they used the known average growth rate of human hair, which is about one centimeter each month, to compute the times when the change occurred. These individuals also supplied a timeline of the most stressful situations they had encountered in the previous year.
The moments when greying or reversal occurred coincided with periods of considerable stress or relaxation, according to this study. Five strands of hair in one person, a 35-year-old male with auburn hair, reversed greying over the same period, which coincided with a two-week vacation. Another participant, a 30-year-old black woman, had one strand of hair with a white section that linked to two months of marital separation and relocation—her most stressful period of the year.
This is a “really innovative and well-conceptualized study,” says Eva Peters, a psycho-neuro-immunologist at the University Hospital of Giessen and Marburg in Germany, who was not involved in the research. However, she adds, given the number of instances the researchers were able to examine was limited—particularly in the study’s stress-related section—more research is needed to validate
