The process of hair going grey is a topic that has always fascinated me. Mainly because I cannot remember a time in my life where my Dad's hair was entirely dark. In my earliest memories, where he was a young thirty-something-year-old, I can recall giggling at what he vehemently swore were little droplets of wisdom on his head (gotitas de sabidurÃa). I am now an early thirty-something-year-old, and let me tell you… Karma exists. I have been steadily greying since around my mid-twenties, which is a tragedy in and of itself, but my resolve for writing this article was actually borne out of an entirely separate observation. In the last few months, I've been noticing an exponential increase in greying hair especially in younger, college-aged students doing the hybrid learning shuffle. So, if it's not simply a matter of aging, what's making us grey?
To answer that question, we first need to know how hair gets its color. Pigmentation is dependent on specific cells living in the hair root, known as melanocytes. These melanocytes develop from melanocyte stem cells (MeSCs), a group of cells that are inactive, suspended in metabolic limbo until they're needed, living in an area called the hair bulge. Their purpose is to migrate to the bottom of the hair follicle once an old strand falls out, and divide in a process called proliferation. Once there, they undergo differentiation, where they change into their final melanocyte form. These melanocytes then create the pigment melanin (the same that determines the color of your skin) and incorporate it into the growing hair. Now, hair grows on a three-phase cycle: hair follicle regeneration (anagen), degeneration (catagen), and rest (telogen). Melanocytes proliferate and differentiate during anagen. They age, as all cells do, and die during the catagen phase. As with all stem cell populations, the MeSC population slowly dwindles as we age. That is why our hair eventually turns grey. However, in some cases, these stem cell populations die off years before they are meant to.
Premature greying of hair (PGH) is a phenomenon where there is a considerable whitening of hair at an early age. The age cut-off for what is considered “prematurely grey†has been roughly estimated by ethnicity, ranging from 20-30 years. In this interval, the former corresponds to those with less total melanin content (lighter skin tones) and the latter for those with more melanin (darker skin tones). There are many causes for premature greying. These include genetics, dietary deficiencies, disorders such as vitiligo, certain types of medication, and stress. If I were to take a guess on why young people are turning grey within the last year, I would probably attribute it to, I don't know, the pressures of trying to survive during a global pandemic, a.k.a. stress. As it turns out, our anxiety can not only throw off our sleep cycles and job performance, but it can actually alter how our cells work.
Melanocyte maintenance and survival are dependent on genes, such as the melanogenesis-associated transcription factor (MITF). Studies have shown that when this MITF gene is turned off or blocked, melanocytes do not survive in the hair bulge and eventually die off, leading to patches of grey hair. However, in the absence of this issue, there are still instances of premature greying. When studied further, it was discovered that melanocytes are sensitive to the hormone noradrenaline, which is released from your sympathetic nervous system. The sympathetic nervous system is the network of neurons that coordinate your body's response to dangerous situations, otherwise known as your fight-or-flight response. Noradrenaline does not only make your stomach flutter and your muscles contract, but it sends your melanocytes into a frenzy. When the sensors on the MeSCs encounter noradrenaline, it causes them to proliferate wildly, exhausting the remaining pool and leaving fewer potential cells for the next round of hair growth.
If you're one of the many who have fallen prey to stress-induced greying, I have good news and bad news. The good news is your hair is actually magical, as the white color we perceive is actually an illusion of light refracting inside the hair shaft (kind of like polar bears!). The bad news is that, short of coloring your hair, it is likely that the lack of color is there to stay. To add to your stresses, greys also require more maintenance, as they are not only more coarsely textured than healthy colored hair, but their growth rates are faster, are able to grow longer, and are more resistant to permanent dyes. This is because melanocytes normally work closely with keratinocytes–the cells that make hair fibers–through the exchange of molecules. When there are no more melanocytes in the hair follicle, the lack of their chemical communication leads to a change in hair structure. Additionally, greys are more sensitive to UV light, heat, and other types of physical stress than the rest of your hair, so they require more heat and sun protectants. Sure, the balance of positives and negatives might seem skewed, but the fact of the matter is grey hair happens to all of us fortunate enough to age. So, thank your lucky stars you've been able to make it this far, during a global pandemic, and rock the silver fox look (and, maybe invest in some stress-relieving hobbies).
About the Author
Ph.D. student in the Department of Physiology and Pharmacology at the University of Georgia, studying strategies for skeletal muscle rehabilitation and regeneration following injury or disease. Interests include mitochondrial physiology, orthopedics, and hugs. Outside of lab, I enjoy reading, listening to true crime podcasts, and griping about the cold like a true Puerto Rico native. You can reach me at jm08293@uga.edu or follow me on Twitter @jey_at_lab.
