A new study found that stress hormone causes hair loss

Can reducing stress be the secret of hair growth?

Generally speaking, a person has three stages of the hair growth cycle: growth, degeneration and rest. In the first stage, the hair is a stem that is continually projected outward, while the hair stops growing and its underside shrinks while remaining in place in the second stage. In the third stage, however, the hair ends up falling out.

Although it has been known for some time that stress is related to hair that prematurely enters the third stage and falls out, as is the general link between hair loss and chronic stress itself, the exact mechanism behind that link has remained a mystery.

What is known is that hair follicle stem cells (HFSCs) play an essential role in hair growth, interpreting internal and external signals. Knowing this, Cho and other researchers tested the role that another area of ​​the body, specifically the stress hormone-producing adrenal gland – played in the cycle. To do this, they removed them from mice by means of surgery.

Without the adrenal glands to produce stress hormones, the “rest” phase of rats in their hair cycles was much shorter, while their hair follicles grew about three times longer than normal. But when fed with the hormone corticosterone, the stress hormone produced by the animals’ adrenal glands, hair growth was suppressed.

So, does corticosterone play a role in hair loss? This is what it implies. HFSCs detect the stress hormone by means of signals, not by detecting the hormone itself. This was determined when the researchers selectively deleted the protein known as glucocorticoid receptors in the dermal papillae. These receptors are the means by which the hormone signals HFSCs.

But how do the dermal papillae transmit the signal? According to the study, this is done by means of another protein, the specific for growth arrest 6 (GAS6). Through this protein, the signal is passed on to HFSC’s through another protein, the AXL receptor.

However, the study warns that several problems still need to be explored in more detail. For example, corticosterone is not the human stress hormone, but is simply considered the rodent equivalent to human cortisol. As such, it is not known whether the process is exactly the same. Second, the phases of the hair cycle have different durations between humans, so it is not clear whether hormones influence the same way. Third, the GAS6 protein is not limited to this particular signal. In fact, the researchers found that it is involved in the expression of several different genes involved with HFSCs. As such, tampering with it can have other unforeseen effects. In particular, it is feared that this could inadvertently lead to the growth of potentially mutating HFSCs.

One of them, known as Trichotillomania, is the condition in which stress, frustration and other negative emotions form an irresistible compulsion to pull out hair, the literal definition of “pull out hair”.

The third way is very different. Known as alopecia areata, this condition is an autoimmune disease and leads to hair loss caused by the body’s own immune system attacking the hair follicles. There are several potential causes for this condition, with high stress being one of them, although, notably, the condition itself is also known to be a cause of significant psychological stress.

However, the study’s findings found valuable links between stress and hair loss, and this could pave the way for future studies that can further explore these links.