How gray hair is caused by stress. Biological puzzle solved.

hair aging

It is a crisis moment for many when they find that a gray hair has just popped out. There are several myths related to gray hair such as do not pluck them out or people with gray hair don’t become bald. Regardless of this, there is no answer as to why do we get gray hair. More often than not people relate it with stress.

Scientists found evidence that supports popular anecdotes on how stress causes gray hair. The researchers found that in mice, the type of nerve involved in the fight or flight response causes permanent damage to the pigment regenerating stem cells in the hair follicle. The findings advance knowledge of how stress impacts the body and are a first step in blocking its negative effects.

Marie Antoinette captured during the French Revolution, experienced hair aging and it turned white overnight. In the most recent history, John McCain suffered serious injuries as a prisoner of war during the Vietnam War and lost color in his hair.

Man with gray hair
Man with gray hair

For a long time, anecdotes have connected stressful experiences with the phenomenon of gray hair. Now, for the first time, scientists at Harvard University have discovered exactly how the process develops. Stress activates the nerves that are part of the fight or flight response, which in turn causes permanent damage to regenerating stem cells of pigment in the hair follicles.

The study, published in Nature, advances scientists’ knowledge about how stress can affect the body and cause gray hair.

“Everyone has an anecdote to share about how stress affects your body, particularly your skin and hair aging, the only tissues we can see from the outside,” said lead author Ya-Chieh Hsu, associate professor at Harvard atem cell institute.

” Our team wanted to comprehend if this connection is true and, if so, how stress triggers changes in various tissues. Hair pigmentation is such an accessible and manageable system to begin with. And besides, we were very curious to see if stress really leads to gray hair “.

Narrowing the culprit

It is a scientific fact that stress affects the entire body. Because of this, the researchers had to narrow down the analysis unit. This means that first, scientist had to find which body system connected stress with hair color. The team first hypothesized that stress causes an immune attack in pigment-producing cells. However, when mice that lacked immune cells showed gray hair, the researchers turned to the hormone cortisol. But once again, it was a dead end.

“Stress always raises cortisol hormone levels in the body, so we think that cortisol could play a role,” said Hsu. In the experiment,  scientists removed the adrenal gland from mice to avoid the production of cortisol-like hormones yet their hair still changed under stress, turning gray.

After systematically eliminating different possibilities, the researchers focused on the sympathetic nervous system. This system is responsible for the fight or flight response of the body. The sympathetic nerves branch into each of the skin’s hair follicles. The researchers found that stress causes these nerves to release the chemical norepinephrine, nearby pigments absorb it and regenerate stem cells.

Gray hair process in mice
Gray hair process in mice

Gray Hair. Permanent damage

In the hair follicle, certain stem cells act as a reservoir of pigment-producing cells. In the process of hair regeneration, some of the stem cells transform into pigment-producing cells that dye the hair.

The researchers found that norepinephrine from sympathetic nerves causes stem cells to become excessively activated. All stem cells become pigment-producing cells, prematurely depleting the reservoir.

“When we started studying this, I expected stress to be bad for the body, but the detrimental impact of the stress we discovered was beyond what I imagined,” said Hsu. In the case of gray hair, the damage caused by stress is permanent.  A few days after the stress period passed. All the stem cells that regenerate the pigment disappeared and the pigment can no longer be regenerated.

The finding underscores the negative side effects of a protective evolutionary response. “Traditionally, acute stress related to the fight or flight response is considered beneficial for the survival of an animal. But in this case, acute stress also causes the permanent depletion of stem cells,” said postdoctoral fellow Bing Zhang lead author of the study.

Answering a fundamental question

In the process to connect stress with hair aging, researchers followed a series of steps. They began with full-body response to then focus progressively on the response of individual organ systems. Secondly, they analyzed cell-to-cell interaction. Finally, molecular dynamics. This process mandated a series of research tools that included organ, nerves and cellular receptor manipulation methods.

This study’s approach was to conduct the analysis from the highest level to the smallest detail. An interdisciplinary collaboration from a wide range of disciplines provided a combination of different approaches to solve a very fundamental biological issue,” said Zhang.

Professor Ya-Chieh, author of the study on the effects of stress on gray hair
Professor Ya-Chieh, author of the study

Collaborators included Isaac Chiu, an assistant professor of immunology at the Harvard Medical School who studies the interaction between the nervous and immune systems.

” Peripheral neurons regulate the function of organs, blood vessels, and the immune system in a high degree. However, information related to how they regulate stem cells is not abundant,” Chiu said.

This study allows knowing how neurons can control stem cells. Their function and also it can explain how they interact at different levels to relate stress with hair aging.”

The results of this study can bring light to understanding the broader effects of stress on various organs and tissues. This understanding will pave the way for new studies that seek to modify or block the harmful effects of stress.

Why do we fear gray hair?

Gerontophobia is basically an irrational fear of the signs of aging and the natural deterioration of our body. In contemporary times, it has become a sort of trend. The usual expressions of it are a boom to lead a healthy life, to be fit and carry out beauty routines. Social networks and media constantly feature content that overvalues health and physical appearance.

Most people suffering from this condition are women over 50 years old. The usual fear is more related to suffer from degenerative diseases and clumsiness. So far it is not possible to avoid getting older because of this we should think that all stages of life are important. Each one can be enjoyed in its own way and has its own rewards.

Leave a Reply

Your email address will not be published. Required fields are marked *