Link Between Stress and Gray Hair

If you watch the career of any politician then you will notice a curious thing happen to them over the course of their time in office – their hair starts to turn gray. Politicians aren't the only people who experience this either – and it seems that any position of stress and worry can cause our hairs to rapidly turn silver (if we don't pull them out first) and there is enough anecdotal evidence of this that most of us assume there is indeed a scientific link between stress and gray hair. But is this the case?

The Science of Gray Hair

Interestingly, while there are plenty of examples out there of stress turning people gray, there is as yet no actual scientific evidence. Here's what we know so far:

For men, usually the first gray hair arrives at around the age of 30, but for women it's 35. This varies greatly however and in some cases can start before a teenager has left high school or conversely much later. Before you see the graying hair it will begin within the sunken pits of the scalp where the hairs grow called 'follicles'. Each of us has around 100,000 follicles and each is capable of sprouting several hairs in their lifetime. At the bottom is a collection of cells responsible for assembling the hairs and these include keratinocytes (epidermal cells) which stack on top of each other and they die leaving behind keratin which gives our hair its strength and texture. Keratin is also key in our nails as well as in the hooves, claws and horns of animals.

Meanwhile while all this is going on, nearby cells called melanocytes create pigment called melanin – the same substance that gives our eyes color and which give us our tans (an albino is someone born with no melanin). Hair melanin is either 'eumelanin' (brown or black) or 'pheomelanin' (yellow) and the various shades and hues of human hair come from differing balances of these substances.

At any point 80-90% of a person's hair is in the active growth stage which lasts around two to seven years before the hair falls out due to the apoptosis (cell death) of the keratinocytes and the melanocytes. Now the head will want to begin building new hair and that's when the cells need to start building again. New keratinocytes and melanocytes are created from satellite stem cells that exist at the bottom of the follicle and the process begins anew. The key point here is that keratinocytes have more longevity than melanocytes – and you basically 'run out' of melanocyte stem cells first resulting in gray hairs sprouting due to keratin with a lack of melanin.

How Stress Could Intervene

While there is as yet no complete theory and no clear link for how stress could lead to gray hair, it would have to occur through the depletion of the melanocyte store in the follicles. One possible theory that has been postulated is that stress leads to an increase in free radicals through reduced immune system function. However this seems somewhat unlikely as otherwise other causes of reduced immune function would also be linked to graying hair (which they are not).

Another possibility is that stress hormones intercept the signals that instruct the melanocytes to deliver melanin to the keratinocytes. This seems like a more likely theory and is backed up evidence showing that local expression of stress hormones can indeed mediate these signals. Some longitudinal studies have also seemed to suggest that this is the case, with people who reported being stressed for 2-3 years also reporting going gray earlier in their lives.

Meanwhile in very rare cases it is possible to lose the color in your hair as a result of illness. For instance in the very rare autoimmune disease 'alopecia areata', the immune system attacks pigmented hairs causing them to fall out and leaving behind only white hairs. This could well have been what caused Marie Antoinette's hair to turn white the night before she was guillotined as according to legend.

Confounding Factors

While it is possible then that stress might reduce the effectiveness of the melanocytes, there are many other factors that contribute to the age at which we go gray. Hair color, gender and genetics for instance would all have an effect and it's more likely that the environmental factor of stress would have a bigger impact on those who were already genetically predisposed to gray hair. Even then, for this to have an effect it would take several years before it started to take effect – at least until the death of their current colored hair.

In conclusion then there is no simple or clear connection between stress and gray hair, and there are many factors that play a role. However a small amount of scientific evidence, along with a wealth of anecdotal evidence, seems to suggest that stress can indeed hasten the graying process. So that's one more reason to go on holiday this year...