Water drop on hairWater drop on hair. Adapted from Rodrigo Menezes / Wikimedia CC BY-SA 4.0

The shade of one’s locks may reflect the state of one’s mind

Jodie Nicotra

At first glance, Martin Picard, who is 37, has a full head of dark auburn hair. But he leans closer to the camera to point out some (still invisible) graying at the temples.

“I have a lot more than I did five years ago,” he says, laughing.

Picard is corresponding author on a recent study that maps how human hair grays in response to stress. It seems that not only can single hairs lose pigmentation in response to stressful events – they can also regain their hair color after the stress is relieved.

The research was done by an interdisciplinary team that included Picard and members of his lab at Columbia University’s Department of Psychiatry, as well as hair experts from Dublin and Miami.

Hair growth over time
Diagram illustrating hair growth over time, method of hair collection, digitization, and hair pigmentation pattern.
Image courtesy eLife. CC BY 4.0

But while their discovery may get attention from an aging-obsessed public, the hair graying study interests Picard and his team for reasons that go beyond vanity.

The researchers found that changes in patterns of melatonin – the pigment that gives hair its color, in response to stress – can be digitally mapped at the molecular level and analyzed. What’s more, the patterns seen in the hair correspond to what the person has experienced during that time.

Hair, Picard explains, is somewhat akin to tree rings.

At its base, where it pops out of the body, hair is a living thing. Hair cells get chemical and electrical signals, including from stress hormones. It is possible that these signals change the proteins and other molecules that get laid down in the hair shaft.

“Hair is in the body at some point and can respond to the stressors; but then it crystallizes into this hard dead stuff and grows outside of the body, and we’re left with a record of our biological history,” Picard said.

Mapping stress through hair

Natural age-related changes in hair
Dark, white, and hairs undergoing natural age-related changes from the younger dark state to the older white state — seen at macroscopic and microscopic resolutions. Image courtesy eLife. CC BY 4.0

To study changes in hair color patterns, the research team first plucked a number of hairs from various body parts of 14 volunteers. They tried to get hairs from each head that were partly gray, as well as some that were all gray and all pigmented.

Next, they pulled the individual hairs completely straight (even ironing the curly ones) and digitally scanned them at a very high resolution – so high that one pixel on the resulting image corresponded to the length a hair grows in an hour of human life. Then they compared the pigmentation patterns of the hair.

Rather than a flat line, Picard said, the images looked more like EEG waves. “What we saw were oscillations that were nonrandom.”

Though those results aren’t in this paper, Picard said that the team did a parallel study to try to more closely map the relation between stress hormones and hair pigmentation patterns. First, they shaved a small amount of hair from an individual who agreed to take part in the study. Two weeks later (and then two weeks after that) they measured each hair as it grew back to find out how fast it grew.

At the same time, this “very compliant participant” collected samples of their own saliva four times a day for two months. The samples were analyzed for stress hormones, and a mathematical model showed a real-time correspondence between stressful events and hair pigmentation patterns – confirming the lab’s suspicions.

Of mind and mitochondria

Examples of hair color reversal
(A) Examples illustrating the reversal of graying along the length of hair shafts in the scalp, (B) pubis, (C), and beard. (F) Diagram illustrating the progression over time of a single dark hair turning gray first, then reverting to its original color. Image courtesy eLife. CC BY 4.0

The hair study was a first for Picard’s Mitochondrial PsychoBiology Lab, which articulates its goal as first uncovering the “bioenergetic mechanisms of brain-body communication” – in other words, understanding through the mitochondria how life events affect us on a biological level. Mitochondria are the powerhouses of human cells. They are actually descendants of bacteria that found their way into a cell and never got out.

“Intrinsically, we care to understand how mind and body are connected,” said Picard. “Our guiding hypothesis is that there’s sort of a mind-mitochondria connection. What we experience in our mind trickles down, or is directly connected, to the molecular stuff that’s happening in the mitochondria.”

The lab’s work forms the foundation of a potential new field in health – what Picard calls “mitochondrial psychobiology.”

Examples of hair shafts graying and reversing
(D) Example of segmental hair shaft with double transitions, including temporary graying and (E) temporary reversal — as seen in an adult and a child, respectively. (G) Closely occurring events of graying and reversal, resulting in hair shafts showing double transitions in color. Image courtesy eLife. CC BY 4.0

Ultimately, studying the mind-mitochondria connection might change the persistent focus on disease that Western medicine has had for much of its history.

“Fundamentally, we know very little about what health is,” said Picard. “All the research that gets funded by the National Institute of Health is centered around disease. As a result, the way we practice medicine and the way we teach doctors is a reactive kind of approach. You have to wait until a disease shows up on a scan until we can do something about your health. And that’s a problem.”

The lab hopes to change this disease-focused model to a more proactive one that focuses on understanding and fostering health. For Picard, the hair color study, which showed that psychobiological states show up in the hair, is a powerful demonstration that mind and body are connected, and that mitochondria might be involved.

Martin Picard
Lead researcher Martin Picard says his work has made him aware what gives him energy and what doesn’t. Pic courtesy Columbia University

Picard imagines a future in which doctors could use digital mapping of hair to decode their patients’ health experiences. They could pull a couple of hairs, scan and analyze them, and ask patients about specific stressful events reflected in their hair.

“It could be really powerful in helping people make decisions, when they know that this affects their biology, to see it as a time series on a continuum,” he said.

So how has studying life processes at the molecular level changed his own approach to life? Picard says that it’s made him not only more aware of how stress affects his body, but more generally what gives him energy and what doesn’t.

“Maybe I’m better than I used to be about engaging with things that inspire me and make me feel energetic,” he said. “And I’m better at saying no to things that are soul-crushing.”

Hair graying and reversal from bulb to tip of a single human hair shaft. Video courtesy eLife. CC BY 4.0
Jodie Nicotra

Jodie Nicotra writes about science and technology. She has taught science writing and many other types of writing at the University of Idaho.

The original report appeared in eLife.

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