Why Does Hair Turn Gray? Scientists May Have Found A New Answer

A new study has shed light on the role our immune system could play in our hair turning gray when we deal with stress or illness.

Cells known as melanocytes make up melanin and give our hair its color. Special stem cells then add melanocytes to new follicles when our hair falls out. When these stem cells stop working, our hair loses its pigment. It is this process and its relationship with our immune system’s defenses that scientists at the National Institutes of Health (NIH) and the University of Alabama, Birmingham, (UAB) set out to investigate—in mice.

Our immune system is constantly defending us against viruses and bacteria, prompting cells under attack to produce signaling molecules called interferons. Interferons tell other cells to turn on the gene expression that prevents viruses from replicating, and trigger immune effector cells that protect the body.

For their paper, published in the journal PLOS Biology, the authors studied how the immune system’s response to attacks affects the MITF protein, which helps melanocytes to function. They found that when MITF loses control of the interferon response in melanocyte stem cells, the hair can turn gray. What’s more, mice genetically predisposed to developing gray hair had this response even when the immune response was turned on artificially. Further research is now needed to understand what caused these reactions and also to see if these effects occur in the human body too.