A new research study explored how stress affects hair loss, and how the body's response to stress has long-term consequences for the scalp.
The researcher Ya Chieh Hsu, a professor of stem cell and regenerative biology, and her colleagues at Harvard University, found that hair loss results from a two-part reaction and that its mechanism belongs to autoimmune diseases.
Immediate hair loss
The first part, which is the immediate hair loss due to stress, was simple, as Hsu explained, and added that it starts with a natural "fight or flight" reaction due to stress, which secretes the hormone norepinephrine, a neurotransmitter that - among other effects - leads to the death of rapidly proliferating cells in hair follicles when its level is very high.
According to "Medical Express", hair loss under such circumstances is usually temporary.
Hsu said: "In the absence of stem cells in this case, hair follicles can be regenerated, leading to temporary hair loss, but then the stem cells activate to renew new hair."
Immune response and long-term effects
However, imaging conducted by research associate Amalia Pasolli, a biologist specialized in electron microscopy, revealed more comprehensive additional details.
She found that the hair follicles that were killed by norepinephrine "looked as if hydrochloric acid had been poured on them" and died from necrosis.
This startling discovery prompted the research team to closely study the tissues, revealing a secondary reaction.
After the secretion of norepinephrine, the researchers found that the body perceives inflamed or dead tissues as an attacking body, leading in turn to a series of immune responses to activate self-reactive T cells.
T cells
Hsu explained that these T cells, which normally work to protect healthy cells, "now see hair follicles as a foreign body that must be attacked."
This secondary attack may have long-lasting effects, as hyperreactive T cells can launch repeated autoimmune attacks on hair follicles when additional stress factors occur.
This possibility opens up avenues for exploration to understand other autoimmune diseases, such as type 1 diabetes, lupus, and multiple sclerosis.
Researchers said it is exciting to see that the effect of psychological stress resembles the same effect of genes regarding baldness.
