For centuries, stories have been told of people whose hair turned prematurely white from harrowing stress. Now, Harvard researchers have found a scientific explanation.
"Marie Antoinette syndrome" is the term commonly used to for the rapid, premature graying, because legend has it that the French queen's hair turned white the night before she faced the guillotine.
Mice get "Marie Antoinette syndrome" when they're highly stressed, too, so Harvard researchers studied them to figure out how stress can induce a permanent loss of hair pigment.
"We started by thinking maybe the immune system is involved," says Harvard stem cell scientist Ya-Chieh Hsu. The hypothesis was that under stress, the immune system attacks the stem cells that generate hair pigment cells.
But when the researchers tested it in mice with defective immune systems that couldn't attack, "They still got gray hairs under stress — so that's incorrect," Hsu says.
Next hypothesis: that the stress hormone cortisol was killing the pigment stem cells. The research team tried removing the adrenal glands that make cortisol, but the mice still developed gray hair.
"So we know that cortisol is not involved," Hsu says.
Finally, the research team focused on the sympathetic nervous system — the network of nerves best known for the "fight-or-flight" response to danger. Hsu says it just didn't seem like a likely candidate, even though it gets activated by stress, because the fight-or-flight response is temporary.
But now it's clear that "a very transient fight-or flight response can lead to permanent changes in stem cells," she says. "That is a much bigger effect than what we would initially anticipate."
The research finds that during stress, the sympathetic nervous system over-activates and so depletes the stem cells that make pigment cells. No more pigment cells — no more hair color.
The paper is just out in the journal Nature.
William Lowry, a biology professor at the University of California, Los Angeles who studies hair follicles, says we've long known there's a connection between stress and graying hair, but not what it was.
"This paper really nails that, in the sense of figuring out what different types of systems in your body come together" to produce the effect, he says.
And that mechanism could apply to more than hair, Lowry says.
"Is this happening in different organs? Is this the canary in the coal mine?" he asks. "I think — sure. There's no reason to think that this is a one-off."
Ya-Chieh Hsu at Harvard says the hope is that understanding how stress harms stem cells could lead to ways to block that harm.
Also --- it's not clear whether the stress mechanism that turns hair white is the same as the normal graying that comes with age, but if it is, there could be a way to block that, too.