Turns out Stress Really Does Turn Hair Gray, Scientists Confirm

Harvard University researchers looked at the nervous system and stem cells to notice how stress affects hair pigment.
Fabienne Lang

The old adage that stress causes hair to turn gray has now been confirmed by Harvard University scientists. 

The reason the French Queen, Marie Antoinette's, hair turned gray after she was captured during the French Revolution may have been because her pigment-regenerating stem cells that color hair follicles "switched off."

Their findings were published in the journal Nature on Wednesday.


Different reasons for stress

"Everyone has an anecdote to share about how stress affects their body, particularly in their skin and hair - the only tissues we can see from the outside," said Dr. Ya-Chieh Hsu, senior author of the study and associate professor of Stem Cell and Regenerative Biology at Harvard University.

Elaborate sympathetic innervation (magenta) around melanocyte stem cells (yellow), Source: Hsu Laboratory/Harvard University

"We wanted to understand if this connection is true, and if so, how stress leads to changes in diverse tissues. We were genuinely curious to see if stress indeed leads to hair graying," continued Dr. Hsu

By process of elimination, the team of scientists was able to get to the root of the problem. 

Initially, the team believed the immune system could be at fault, going haywire over extreme periods of stress and attacking pigment cells. However, in the mice without immune systems that the scientists observed, their hair still turned gray. 

Next, they looked at whether the stress hormone cortisol was to blame, but mice without adrenal glands' hair still turned gray regardless.

Finally, the team looked into the body's fight-or-flight response system, the sympathetic nervous system. These nerves branch out into hair follicles on our skin. The researchers discovered that when stressed, these nerves released a chemical called norepinephrine.

This chemical causes the stem cells to overact and overwork, releasing too much pigment and ultimately running out of their color reservoir. 

Infographic depicting how stem cells are depleted in response to stress, causing hair to turn gray in mice, Source: Judy Blomquist/Harvard University

Once hair turns gray, there's no going back

Unfortunately, once that reservoir is depleted there's no going back. Hence, gray, uncolored, hair. As Dr. Hsu confirmed "After just a few days, all of the pigment-regenerating stem cells were lost. Once they're gone, you can't regenerate pigment anymore. The damage is permanent."

Senior author Ya-Chieh Hsu shows off a diagram of a hair follicle — complete with a helpful test mouse, Source: Jon Chase/Harvard University

The scientists hope that their research will help illuminate the wider effects of stress on different organs and tissues and clear the path for the creation of drugs that can counter this graying effect.

Dr. Hsu commented "Understanding how our tissues change under stress is the first critical step towards eventual treatment that can halt or revert the detrimental impact of stress. We still have a lot to learn in this area."