Can stress really make hair (or fur?) turn gray?

It seems like common knowledge or conventional wisdom: stress can turn your hair gray.

Whether it’s the kids, your spouse, your job, or something else, people with gray hair have been blaming stress for centuries.

The example of Barack Obama is often cited: his hair was quite dark when first elected president, but by the time he’d completed his second term, it was much grayer. Clearly it was the stress of his job, right?

Not so fast! As I wrote in a previous post, the notion that stress makes you gray may be largely myth. Certainly, there are factors other than stress that lead to graying, not the least of which are genetics and age. And plenty of people under significant stress never go gray.

Keep in mind that an individual strand of hair does not change color (unless it’s dyed). When we see someone going gray, it’s usually because strands of hair with color (pigment) have fallen out and hairs without pigment have grown in their place. When a large enough number of unpigmented hairs grow in, the change is noticeable, and a head of hair appears to turn gray. Typically, this happens because pigment-producing cells within hair follicles produce less color over time. While graying commonly starts during middle age, genetics plays a role in when it begins.

What is stress anyway?

While it’s a popular and well-accepted notion that stress is bad for your health, if you’re facing a charging tiger, the body’s response to this sudden (acute) stress can be lifesaving. Your heart races, blood pressure and blood sugar rise, blood vessels in your muscles dilate, along with other physiologic reactions that prepare you to fight or flee (and in this case, I’d recommend the latter).

And while chronic stress may have negative health consequences, different people respond to the same stressors differently. In fact, it can be hard to define stress: what one person finds terrifying and unpleasant (for example, public speaking) another person may find exciting and energizing.

Maybe it’s true after all: A new study finds stress can turn hair gray

You may have seen news reports about a new study suggesting that stress can turn hair gray and sorts out how it happens. But there’s one important caveat: the study was performed in mice whose fur turned gray within a few days of their being injected with resiniferatoxin (a substance similar to the active, irritating ingredient in chili peppers). Whether the findings apply to humans is not yet known, but this research does provide a scientifically plausible explanation of how it might happen.

In the January 22, 2020, edition of Nature, researchers describe a series of experiments suggesting that in mice, sudden stress leads to the following sequence of events:

• Stimulation of nerves causes the adrenal gland to increase production and release of norepinephrine, a close cousin of epinephrine (also called adrenaline).
• Norepinephrine causes certain cells in the skin’s hair follicles (called melanocyte stem cells) to rapidly divide and turn into pigment-producing cells.
• This depletes the melanocyte stem cells in the hair follicles, leading to loss of pigment in the hair shafts; when a large number of individual hair shafts lack pigment, the fur appears gray.

If these events also occur in humans, these findings could lead to treatments that prevent graying. Indeed, when researchers prevented melanocyte stem cells from dividing rapidly in the mice, their fur did not turn gray.

So what?

Media reports regarding this study suggest it cracks the code on the connection between stress and graying hair, and affirms that notion that work or family stress is turning you gray.

But, that’s not what this research showed! In fact, there are a number of reasons to be skeptical about how important these results are:

• Mice and humans are different. Often medical studies in animals turn out to be impossible to replicate in people.
• There’s a big difference between acute and long-term (chronic) stress. The acute stress experienced by the mice in this study is not the type of chronic stress most people think of when explaining gray hair. Of course, it’s not easy to design a mouse study that simulates chronic human stress such as daily traffic jams, a challenging job, or relationship trouble.
• Not all acute stress is the same. It’s not at all clear that the acute stress mice experienced after being injected with resiniferatoxin and their fur graying within a few days is applicable to the way humans experience stress or go gray.

The bottom line

The findings of this study are intriguing and potentially important, to explain changes in hair color and advance our understanding of how stress affects other parts of the body.

These findings have made me rethink the idea that stress-induced gray hair is a myth. Maybe it can happen, but only rarely. Or, perhaps stress is responsible for most or all of the gray hair in the world. One thing’s for sure: we’ll need a lot more research to know which of these is true.

If your hair is turning gray, you can blame your kids, your boss, or other sources of stress in your life. And you can point to this new study to support your perspective. But, until there is evidence that the findings of this study apply to people, I think it’s still more appropriate to blame your parents — and Father Time.

Follow me on Twitter @RobShmerling