Scientists discover how stress causes hair loss

Harvard scientists found evidence that links hair to chronic stress suggesting possible ways to restore hair growth. Scientists at Harvard University have identified the biological mechanism by which chronic stress impairs hair follicle stem cells. Many people talk about what happens to their skin and hair when they are stressed. The latest study confirms these long-standing observations suggesting that stress might actually lead to hair loss. 



In a mouse study, the searchers found that a major stress hormone puts hair follicle stem cells into a long resting phase. During this phase, hair follicles are not regenerated. The researchers identified the specific fell type and molecule responsible for relaying the stress signal to the stem cells. They also showed that these can be targeted to restore hair growth. They hair follicle is one of the few mammalian tissues that can undergo rounds of regeneration throughout life. 

During the growth phase, hair follicle stem cells become activated to regenerate the follicle and hair. During the resting phase, hair shed more easily. Hair loss can occur if the hairs shed and the stem cells remain dormant. By studying the skin, researchers found that stress does actually delay stem-cell activation. In a study on a mouse model they found that corticosterone was overproduced by chronic stress. Corticosterone is a major stress hormone produced by the adrenal glands. 

Giving mice corticosternoe reproduced the stress effect on the stem cells. The equivalent hormone in humans in cortisol which is also overproduced under stress and is often referred to as the “stress hormone”. But when researchers removed the source of the stress hormones the stem cells’ resting phase became extremely short. The mice constantly entered the growth phase even when they were old. 


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