Stress can turn hair grey but it is reversible, researchers find

Stress can turn hair grey but it is reversible, researchers find.

Legend has it that Marie Antoinette’s hair turned grey overnight just before her beheading in 1791. Though the legend is inaccurate, hair that has already grown out of the follicle does not change colour, a new study from researchers at Columbia University Vagelos College of Physicians and Surgeons is the first to offer quantitative evidence linking psychological stress to greying hair in people.

And while it may seem intuitive that stress can accelerate greying, the researchers were surprised to discover that hair colour can be restored when stress is eliminated, a finding that contrasts with a recent study in mice that suggested that stressed-induced Gray hairs are permanent.

The study has broader significance than confirming age-old speculation about the effects of stress on hair colour, says the study’s senior author Martin Picard, associate professor of behavioural medicine at Columbia University Vagelos College of Physicians and Surgeons.

“Understanding the mechanisms that allow ‘old’ grey 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,” Picard said

“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.

“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,” Picard says. “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,” he added.

Though people have long believed that psychological stress can accelerate grey hair, scientists have debated the connection due to the lack of sensitive methods that can precisely correlate times of stress with hair pigmentation at a single-follicle level.

Splitting hairs to document hair pigmentation Ayelet Rosenberg, first author on the study and a student in Picard’s laboratory, developed a new method for capturing highly detailed images of tiny slices of human hairs to quantify the extent of pigment loss (greying) in each of those slices. Each slice, about 1/20th of a millimetre wide, represents about an hour of hair growth.

“If you use your eyes to look at a hair, it will seem like it’s the same colour throughout unless there is a major transition. Under a high-resolution scanner, you see small, subtle variations in colour, and that’s what we’re measuring,” Picard said.

The researchers analysed 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 investigators immediately noticed that some grey hairs naturally regain their original colour, which had never been quantitatively documented.

To better understand how stress causes grey hair, the researchers also measured levels of thousands of proteins in the hairs and how protein levels changed over the length of each hair.

Changes in 300 proteins occurred when hair colour changed, and the researchers developed a mathematical model that suggests stress-induced changes in mitochondria may explain how stress turns hair grey.

The mitochondria connection between stress and hair colour differs from that discovered in a recent study of mice, which found that stress-induced greying was caused by an irreversible loss of stem cells in the hair follicle.

Reducing stress in your life is a good goal, but it won’t necessarily turn your hair to a normal colour.

“Based on our mathematical modelling, we 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 grey,” Picard said.

“But we don’t think that reducing stress in a 70-year-old who’s been grey for years will darken their hair or increasing stress in a 10-year-old will be enough to tip their hair over the grey threshold,” he added.

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