In a recent study from Harvard University, scientists have uncovered an important cause of grey hair: stress.
The research team found that stress activates nerves associated with the fight-or-flight response, causing permanent damage to pigment-regenerating stem cells in hair follicles. This discovery sheds light on how stress can impact the body in significant ways.
The study, conducted by Ya-Chieh Hsu and colleagues, was published in the journal Nature. The researchers aimed to investigate the widely held belief that stress leads to grey hair and to understand the underlying mechanisms.
Since stress affects the entire body, they first needed to pinpoint which body system links stress to hair color changes.
Initially, the researchers hypothesized that stress might trigger an immune attack on pigment-producing cells. However, when they observed that mice lacking immune cells still experienced hair graying, they ruled out the immune system’s involvement.
Through a process of elimination, the team focused on the sympathetic nervous system, which governs the fight-or-flight response.
The sympathetic nerves extend into each hair follicle on the skin. The researchers discovered that stress prompts these nerves to release norepinephrine, a chemical that is absorbed by nearby pigment-regenerating stem cells.
These stem cells usually serve as a reserve for producing pigment-producing cells when hair regenerates, giving hair its color.
The study revealed that norepinephrine causes these stem cells to become hyperactive, leading them all to convert into pigment-producing cells. This excessive activation depletes the stem cell reservoir prematurely, resulting in the loss of hair color and the onset of grey hair.
This finding highlights a downside of the body’s evolutionary response to stress.
The researchers demonstrated that stress-induced graying starts with a whole-body response and narrows down to specific organ systems, cell interactions, and molecular dynamics. Their approach involved various research tools to manipulate organs, nerves, and cell receptors.
Understanding this connection between stress and grey hair can help scientists explore the broader effects of stress on different organs and tissues.
This knowledge could pave the way for new studies aimed at modifying or blocking the harmful effects of stress, potentially leading to new treatments or preventative measures.
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