Researchers in the United States have found that prematurely greying hair is caused by stress.
Don’t we know that already? Sure, but this is an instance where science has finally caught up with common wisdom – in a study that is the “first to offer quantitative evidence linking psychological stress to greying hair in people”.
But here’s the surprise. Hair colour changes subtly all the time, due in part to fluctuating stress levels.
But in a fascinating experiment from Columbia University, when stress was removed from greying participants (who went on vacation) the follicles that had started producing grey hair reversed course.
And they got your natural colour back.
Now the researchers are wondering: what other signs of ageing can be reversed?
It’s an old story
Every family has a story about an uncle or sister or maybe it was you: After a period of stress, grey hairs started turning up on your head.
The stress continued and, within a year, just about all your natural colour was gone – and you weren’t even that old.
Much of the evidence for this phenomenon has been anecdotal – and some of it has been very public.
In March, 2009, The New York Times reported: “Well, that didn’t take long. Just 44 days into the job, and President Barack Obama is going grey.”
Most of the grey science has been done with mice
One mouse study found that greying hair was caused by an irreversible loss of stem cells in the hair follicle. Once the hair went grey, there was no coming back.
Another study suggested that hair goes grey because the cells that produce melanin – the pigment that largely colours our skin, eyes and hair – also produce hydrogen peroxide, the agent often used for creating bottle-blonde hair.
The chemical is normally broken down by an enzyme called catalase. But the production of catalase drops as we age, and the hydrogen peroxide takes over.
But that’s not how it work for humans
The new research linked stressful episodes with hair going grey in real time – and appears to be a result of signalling from the mitochondria, where cells produce energy.
“We often hear that the mitochondria are the powerhouses of the cell, but that’s not the only role they play,” said senior author Martin Picard, associate professor of behavioural medicine (in psychiatry and neurology) at Columbia University Vagelos College of Physicians and Surgeons.
“Mitochondria are actually like little antennas inside the cell that respond to a number of different signals, including psychological stress.”
What happened in the study?
The researchers analysed individual hairs from 14 volunteers.
For this analysis, the team 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 a 20th of a millimetre wide, represents about an hour of hair growth.
Under a high-resolution scanner, they were able to measure small, subtle variations in colour.
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 scientists found “striking associations between stress and hair greying” and, in some cases, they saw a reversal of greying with the lifting of stress.”
Dr Picard said: “There was one individual who went on vacation, and five hairs on that person’s head reverted back to dark during the vacation, synchronised in time.”
The bigger picture
The researchers believe their study has “broader significance than confirming age-old speculation about the effects of stress on hair colour”.
Understanding the mechanisms that allow ‘old’ grey hairs to return to their ‘young’ pigmented states “could yield new clues about the malleability of human ageing in general and how it is influenced by stress,” said Dr Picard.
He said the study’s findings provide new evidence “demonstrating that human ageing is not a linear, fixed biological process but may, at least in part, be halted or even temporarily reversed”.