How chronic stress leads to hair loss

NEW YORK: Researchers have identified the biological mechanism by which chronic stress impairs hair follicle stem cells, confirming long-standing observations that stress could lead to hair loss.

In a study on mice, published in the journal Nature, researchers found that a major stress hormone places hair follicle stem cells in a prolonged resting phase, without regenerating the follicle or hair.

Researchers have identified the specific cell type and molecule responsible for transmitting the stress signal to stem cells and have shown that this pathway can be potentially targeted to restore hair growth.

“The skin provides a treatable and accessible system to study this important problem in depth, and in this work we found that stress actually delays stem cell activation and fundamentally changes the frequency with which hair follicle stem cells regenerate tissue, ”said researcher Ya- Chieh Hsu of Harvard University.

The hair follicle goes naturally between growth and rest, a process fueled by stem cells from the hair follicle. During the growth phase, the stem cells of the hair follicle are activated to regenerate the follicle and the hair, and the hairs grow longer every day.

During the resting phase, the stem cells are at rest and the hairs fall out more easily. Hair loss can occur if the hairs fall out and the stem cells remain at rest without regenerating new tissue.

The researchers studied a mouse model of chronic stress and found that hair follicle stem cells remained in the resting phase for a very long time without regenerating tissue.

A major stress hormone produced by the adrenal glands, corticosterone, was upregulated by chronic stress; giving corticosterone to mice mimics the effect of stress on stem cells.

The equivalent hormone in humans is cortisol, often referred to as the “stress hormone”.

Under normal conditions, the regeneration of hair follicles slows down over time – the resting phase lengthens as animals get older.

But when the researchers eliminated the stress hormones, the resting phase of the stem cells became extremely short, and the mice constantly entered the growth phase to regenerate hair follicles throughout their lives, even when they were. elderly.