Many people complain of hair loss after experiencing health problems or extreme mental stress. Unlike androgenetic alopecia, which is caused by male hormones, the main cause of alopecia areata or telogen effluvium is known to be stress.
However, it has not been clearly proven how stress specifically causes hair loss or why hair loss recurs even after the stressful situation has been resolved.
A research team at Harvard University in the United States has identified the specific cause and recurrence of stress-related hair loss, which has been shrouded in mystery. It was discovered that stress not only directly destroys hair follicle cells, but also leaves memories in our body’s immune system, leading to chronic recurrence. The results of this study were published in the latest issue of Cell, the world’s most prestigious journal in the field of biology.
According to Harvard University Professor Ya-Chieh Hsu‘s research team, the main culprit of stress-related hair loss was our body’s ‘sympathetic nervous system’. When the body is under extreme stress, it switches to ‘fight or flight’ mode for survival, and at this time, a large amount of the neurotransmitter ‘norepinephrine’ is released from the terminals of activated sympathetic nerves.
The problem is that hair follicle migration amplifying cells (HF-TAC), which play a key role among hair follicle cells that produce hair, are very vulnerable to this substance. Norepinephrine stimulates the receptors of these cells, causing calcium to flow abnormally into the mitochondria, the energy factories within the cells.
Professor Xu explained, “When calcium suddenly pours in, mitochondria break down and eventually ‘necrosis’ occurs, in which cells with broken energy balance burst and die.” Unlike cells that quietly disappear during the normal aging process, this is a phenomenon in which cells are destroyed as if they explode due to external shock.
When the research team artificially subjected mice to extreme stress by injecting them with resiniferatoxin, a component similar to capsaicin, it was confirmed that 30% of the mice’s hair follicle cells died through necrosis in just 24 hours. A strong inflammatory response occurred around the necrotic hair follicle cells, and immune cells began to attack the hair follicle cells. This led to an autoimmune reaction that destroyed hair follicles in the area, or ‘alopecia areata’.
Immune cells remember hair loss
More importantly, the mouse’s immune system remembered this. Even though the research team gave only very weak inflammatory signals to mice that had recovered from hair loss due to stress, the immune cells attacked the hair follicles again and hair loss recurred.
On the other hand, rats with no experience of stress showed no response to the same stimulus. In other words, it has been confirmed that once hair loss occurs due to stress, hair loss recurs even with mild stimulation.
In fact, about 40% of patients with alopecia areata experience great psychological pain due to recurrence of hair loss even after treatment. Telogen effluvium also often becomes chronic or recurs periodically.
Professor Xu predicted, “This study shows that stress leaves permanent memories in the immune system, which can lead to chronic diseases. Blocking signals from the sympathetic nerves or preventing calcium from entering the mitochondria could be a new direction for treatment.”
