Does stress make you gray?

Gray hair is a sign of natural aging processes. But stress can also contribute to graying. (Image: Ekaterina79 / istock)

Stress makes you sick in the long run – and gray, they say. Stressed people get gray hair earlier. But is that also true? Researchers have actually been able to prove this: experiments with mice have shown that the activation of the sympathetic nervous system leads to changes in the pigment-forming cells in the hair follicle and, as a result, to loss of color.

Whether blond curls or dark hair: at some point every hair begins to turn gray. At first it is mostly just individual strands, but over time, more and more hair loses its former color. Because with increasing age, the body produces less melanin. Different variants of this color pigment usually give our hair its characteristic color. How early the graying process begins is a matter of disposition. But external influences should also be able to promote premature graying – for example stress. According to legend, the French Queen Marie Antoinette even went gray overnight when she learned of her impending execution. “It is a common belief that stress makes hair pale. For a long time, however, there was no scientific evidence of this, ”explains Thiago Cunha from Harvard Medical School in Boston. So does the psychological stress really cause gray hair?

Black mice become gray

Cunha and his colleagues around first author Bing Zhang from Harvard University in Cambridge have established that this phenomenon does indeed exist – and what mechanisms it is based on. The starting point of their work was a chance discovery: in experiments with mice, the researchers observed that some of the previously black rodents suddenly got light fur. The exciting thing: These animals were deliberately inflicted pain in the experiment, they had suffered acute stress. “We wanted to investigate whether the color loss was related to the pain-induced stress,” reports Cunha. To do this, he and his colleagues prevented the transmission of signals via the sympathetic nervous system. This part of the autonomic nervous system is responsible, among other things, for our reaction to stress and danger. It controls the so-called fight-or-flight reaction and triggers, for example, the release of stress hormones that make our heart beat faster.

The results revealed that if this influence was inhibited with the help of medication or the removal of sympathetic nerve fibers, the mice actually did not turn gray after the stressful ordeal. “These and other experiments suggested that the sympathetic nervous system is involved in the loss of pigment in the hair and that pain in this case acts as a powerful stressor,” summarizes Cunha. But how exactly do signals transmitted via this system turn hair gray? The scientists finally found an answer to that too. They found that acute stress affects the melanocytes in the hair follicle. “These pigment-producing cells are as undifferentiated as stem cells when they are young, but they mature with increasing age. When this process is complete, they stop producing melanin and migrate, ”explains Cunha.

Norepinephrine release with consequences

Specifically, it was found that when there is physical or psychological stress, sympathetic nerve fibers that end in the hair follicle release more norepinephrine. The melanocyte stem cells in turn have a receptor for this messenger substance – if it is activated, they begin to differentiate. Strong activation of the sympathetic nervous system therefore accelerates the natural aging process of the pigment-producing cells in the hair. If they are lost, there is no more color supply. “The damage is permanent,” says co-author Ya-Chieh Hsu from Harvard University. But there is good news: this stress effect can possibly be prevented. In search of a potential antidote, Cunha and his colleagues investigated how stress changes the gene expression in cells. Particularly noticeable was a section of DNA that contained the building instructions for a protein called CDK – this protein plays an important role in regulating the cell cycle.

As the scientists report, the activity of the CDK gene increased due to stress. But what would happen if this protein were blocked? To find out, the team repeated the pain experiment with the mice, but this time gave them a CDK inhibitor. And indeed: unlike before, there was no premature differentiation of the melanocyte stem cells and the rodents retained their dark coat color. Further experiments with human melanocytes confirmed that a very similar mechanism takes place in humans. “This suggests that CDK could be a point of attack for therapies against graying,” states Cunha. However, it remains unclear whether such a product will one day be available in pharmacies.

Not just hair affected?

All in all, the study once again made it clear what lasting consequences stress can have on our bodies and our health. The fact that this type of exposure affects pigment-producing stem cells in the hair follicle means, according to the researchers, that other tissues and organs could be affected in a similar manner. “We assume that other systems in the organism show comparable reactions to intense stress,” write Cunha and his colleagues.

Source: Bing Zhang (Harvard University, Cambridge) et al., Nature, doi: 10.1038 / s41586-020-1935-3

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