Recent Study: Gray Hair Can be Caused by Stress

By: Tamar Nicole Soussana  |  February 6, 2020

By Tamar Nicole Soussana, Staff Writer

In my article titled, “Is that a Gray Hair? The Science Behind Pigmentation,” I researched the causes of gray hair and found it was highly probable that this phenomenon is solely due to genetics and general aging, and has no real roots in how stressed a person is. However, according to a study published on January 22, 2020 in the journal Nature, evidence suggests that stress may be an underlying factor in the transformation of hair from colored to gray. 

Prior to the publication of this study, there was little scientific evidence to justify the correlation between stress levels and an abundance of gray hair. A team of researchers from Harvard University successfully conducted experiments on mice in order to conclude whether this was backed by scientific fact. 

In order to decisively state that stress leads to gray hair, the scientists had to outline the mechanism of this process, as stress can affect many parts of our bodies. The first step was to experiment with the body’s immune response. Our immune system responds to any sort of injury, wound, or foreign object in the body. By inserting the chemical capsaicin, an irritating factor of chili peppers, the mice would undergo acute stress and the scientists hypothesized that there would be an immune attack on melanocyte stem cells. Even mice, which lack immune cells, began to gray. 

The next hypothesis was to see if cortisol, a stress hormone, was responsible for causing gray hair. Mice with removed adrenal glands, organs located above the kidneys, and producers of necessary hormones, still produced gray hair under stress. 

Scientists then looked at the sympathetic nervous system. This system is the source of the “fight-or-flight” response to dangerous or stressful circumstances. The researchers found that noradrenaline (or norepinephrine) was released by the sympathetic nervous system and consumed by the melanocyte stem cells during times of stress. These cells proliferated (rapidly increased), became specialized for pigmentation, and then left the follicle permanently. Without a melanocyte, the follicles no longer had a source of color. Therefore, the absence of color, or white, subsumes. 

The scientists also discovered that if they halt the proliferation of stem cells, or block the release of noradrenaline, they can also stop the process of graying hair. It is important to recognize, however, that stress is not the only factor in graying hair, as genetics also plays a role. 

Other than learning about the additional factor which leads to our gray hairs, this study also sheds light on the difficulties and beauties of the scientific discovery process. The researchers had a question about stress and gray hairs, attempted multiple hypotheses, and were left empty-handed. But despite these dead ends, they pursued their research further and came out with a scientific statement never before discovered. This is a great lesson of perseverance which we can take with us, despite the kind of careers for which we may strive. 

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