The notion that stress can cause hair to turn gray isn’t entirely a myth: at least when it comes to genetic stress applied to laboratory mice. That’s what researchers found when they damaged mice’s DNA with ionizing radiation, according to a study published in the journal Cell.
Scientists already knew that cells known as melanocyte stem cells were responsible for youthful hair color. Each of these cells divides into two cells: One that replaces itself and another that differentiates into a pigment-producing daughter cell called a melanocyte, which imbues hair with its browns, reds and blacks. Earlier research has suggested that the depletion of these stem cells was to blame for grayness. But how exactly these stem cells disappeared was mysterious. With no more stem cells around to produce melanocytes, hair turns gray [Science News].
When the researchers inundated the mice with radiation that damaged the animals’ DNA, the mice’s fur turned from brown to gray (see photo). The researchers found that the damage caused the stem cells to mature, so that the stem cells of the irradiated mice stopped copying themselves [Bloomberg]. Scientists say that this effect may be due a protective mechanism in the body. Maturing melanocyte stem cells may be a way of preventing cells whose DNA has been damaged by toxins from becoming cancerous…. “Graying may actually be a safety mechanism, that’s a cool twist” [Bloomberg], comments dermatology researcher David Fisher, who wasn’t involved in the current research.
The results might help explain why people with the rare neurodegenerative disorder known as Ataxia telangiectasia have gray hair at an early age. The syndrome is caused by a mutation in a gene called ATM. In their study, [the researchers] found the ATM “caretaker” gene serves as a checks and measures system to stop melanocyte stem cells going awry [BBC]. A mutated version of the ATM gene might be overzealous in maturing melanocyte stem cells, researchers suggest.
However, the new study does not support the still-unproven common claim that emotional stress causes graying–at least not yet, says Fisher. “With this mechanistic insight,” he notes, “we might finally be able to look at questions like that one” [ScienceNOW Daily News].
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DISCOVER: How Our Hair Turns Gray
Image: Inomata et al./Cell 2009
June 15th, 2009 at 2:10 pm
I don’t want to cause a panic, but, does this mean that people of my generation who grew up in the 1980′s, in the UK, with “salt & pepper” hair (going grey since I was 21 may I add) – are indeed half baked from the fallout from Chernobyl?
June 15th, 2009 at 2:15 pm
…or Microwaved foods…
June 15th, 2009 at 3:34 pm
what about baldness? At least you can dye your hair.
June 15th, 2009 at 5:55 pm
So that’s why gray sideburns were considered distinguished in the 50′s-they signified exposure to radiation and therefore prosperity.
June 16th, 2009 at 11:02 am
I hope this new research helps to debunk the (scientifically propagated) myth that gray hair is just white hair thrown in among dark hair. (IOW gray is just a variety of salt and pepper). That’s the version I’ve heard somewhere in some reporting of scientific work. If it’s true that a single strand of gray hair also produces no pigment at all, then there must be some structural change when the hair turns white from gray that makes it look white.
BTW the Baltic people (at least the ones who don’t start out very blond) don’t go white until they pass about 100. My dad was merely gray salt and pepper at 90, my dad’s cousin had dark brunette hair at 80 (don’t know now tho), my grandma had gray hair at 100 (very white when she died at 104 tho and the other grandma turned white before 103). Don’t know about the g-g-…uncle who died at 120 in 1826 and who fathered kids at 92. (BTW the gerontologists ought to study the people from along the border of Latvia and Lithuania; from my genealogical research, every year in the decades between 1840 and 1860, about 1% of the people (including babies) who died that year were centenarians and a few (like that gg..uncle) were super-centenarians.)
August 20th, 2009 at 12:15 pm
Hi , I live in iran , i want to know , are you a method or drug for reversing gray hair ?
December 23rd, 2009 at 9:52 am
Some people go gray at a young age – as early as when they are in high school or college – whereas others may be in their 30s or 40s before they see that first gray hair. This means that most of us will start having gray hairs around the same age that our parents or grandparents first did.