Alot of people believe that stress contributes to grey hair. Just look at the various US presidents who left office with many more silvery strands than when they were sworn in.

But if you dig into the available research, you’ll find that few studies on the topic exist. And while some have found associations between premature greying and stress, no research has proved the link.

“There’s still a lot we don’t know,” said Dr Paradi Mirmirani, a dermatologist at Kaiser Permanente Vallejo Medical Center in Northern California, US.

In past studies, researchers have asked participants to fill out questionnaires about their hair colour and stress levels, and then scientists would see if they could link them.

In one study published in 2016, for instance, scientists surveyed more than 1,100 young Turkish adults and found that the 315 who reported prematurely greying hair had higher stress levels than those who didn’t. (Those with premature greying also had histories of alcohol use and chronic disease, and they had parents who went grey at a young age.)

But a study on mice published in 2020 took the research a step forward. In it, researchers stressed mice in various ways, including by injecting them with a chilli-like chemical that induced a fight-or-flight response. This caused them to release the stress hormone norepinephrine, which, in turn depleted the hair follicles of the stem cells involved in adding pigment to mouse fur. The hair then grew in grey.

Researchers demonstrated similar effects of high levels of norepinephrine on human stem cells as well, supporting the idea that the stress hormone is linked with greying in humans, said Ya-Chieh Hsu, a professor of stem cell and regenerative biology at Harvard University, US, and one of the authors of this research.

But studies on this topic are challenging to perform on people because researchers can’t ethically induce artificially high stress responses in humans like they can in animals or cells, Hsu said.

One small human study published in 2021 still advanced the narrative: researchers plucked various strands of hair from 14 volunteers who had at least some greying. Several of the strands were fully grey, some were partially grey, and some hadn’t greyed at all. The scientists then created high-resolution digital images of the hairs and calculated when each strand went grey using estimates of how quickly hair grows.

They also asked the participants to plot out stressful experiences from the past year on a timeline and rank them from least to most distressing. The researchers found that when a strand turned grey frequently corresponded with the most stressful moment of that volunteer’s previous year.

This was the first time a study linked specific stressful events with the exact moment hair began to grey, said Martin Picard, an associate professor of behavioural medicine at Columbia University, US, and an author of the study.

It offered “our first real evidence that maybe stress does, in fact, play a role for some people,” said Dr Victoria Barbosa, associate professor of dermatology at the University of Chicago, US.

If such preliminary research continues to identify stress-related changes that cause hair to go grey, it may one day lead to treatments that can repigment hair, Dr Mirmirani said. But we still need more and larger human studies to confirm the links, Dr Barbosa said.

Future research might also help explain why stress is linked with hair greying in some people but not in others, said Dr Sindhuja Sominidi Damo- daran, a dermatologist at the Mayo Clinic in Rochester, Minnesota, US.

It’s also too soon to know if easing stress could slow or reverse premature greying.

For most people, genetics is the main driver of greying, Dr Barbosa said. If you have a parent who went grey at a young age, you’re likely to as well.

Certain medical conditions can cause hair to lose pigment prematurely, Dr Barbosa said. Those include vitiligo, which causes patches of skin to lose colour, and alopecia areata, a type of hair loss. An over or underactive thyroid and chemotherapy treatments can also contribute to premature greying, Dr Damodaran said. Deficiencies in iron, calcium, and vitamins B12 and D are correlated with going grey early too, she said, as are obesity and smoking.

Dr Barbosa said she likes to use greying as an opportunity to talk with her patients about accepting going grey as a natural part of ageing. This can be especially liberating for women, she said, since “greying has always been socially more acceptable for men”.

NYTNS