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Scientists say findings may explain initiation of alopecia
Vishwam SankaranThursday 27 November 2025 08:58 GMTComments
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A single stressful life event may be enough to lead to recurrent hair loss, a new study suggests.
Researchers from Harvard University found that when hair follicles died during a stressful event, the body's immune system was primed to attack more hair follicles during future events of a similar nature.
It is well known that stress affects health, including the functioning of the immune system.
However, the exact ways in which a single stressful experience can damage different tissues remain poorly understood.
In particular, it remains unclear whether an acute stress episode can leave lasting effects.
Some previous research has hinted that stress could have both immediate and long-term effects on hair follicles.
Now scientists say that stress in mice can trigger hair loss and rapidly trigger the immune system’s T cells to cause recurrent hair loss in the future.
A doctor makes hairline markings on the scalp of a hair transplant patient (AFP via Getty)Researchers say that strong acute stress hyperactivates the mouse sympathetic nervous system, responsible for increased heartbeat and muscle strength for a "fight-or-flight" response.
This then activates the mouse immune system’s CD8+ T cells, which are capable of attacking hair follicles.
Even after the initial stress subsides, these T cells can drive recurrent hair loss upon subsequent inflammation, researchers say.
“Our findings show that a single acute stress episode causes immediate damage and, in doing so, activates and expands rare autoreactive CD8+ T cells, priming the tissue for future immune attack,” they write in the study published in the journal Cell.
“Thus, a single acute stress episode can cause immediate harm and, in doing so, predispose the same tissue for future damage.”
This kind of immune response may be a way in which bodies sacrifice metabolically costly but replaceable cells to preserve essential stem cells, scientists suspect.
By sacrificing some hair follicles when under threat, they say mice bodies could be preserving stem cells that regenerate tissue once the threat has passed.
This may represent a “strategic compromise to conserve limited resources for critical stress responses”.
“In summary, our study reveals how stress damages tissues both acutely and over time. These mechanisms may help explain the initiation of alopecia areata and its frequent association with stress,” they conclude.
The findings may also help better understand conditions like multiple sclerosis, type 1 diabetes, and lupus, where the causes remain complex, scientists say.
Scientists hope further research on stress-induced hair loss in human tissues can help better unravel the complex causes behind these conditions.
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