It is a well known fact that “stress” causes premature greying of the hair. Rapid greying of hair is called Marie Antoinette syndrome named after Queen Marie Antoinette of France, whose hair allegedly turned white overnight before her last walk to the guillotine during the French Revolution. She must have been “stressed” the night before her beheading would be an understatement. It is no surprise that famous heads of states around the world exhibit rapid greying after taking office. Well, does “stress” really cause greying of hair? Scientists may have finally found the truth.

Ya-Chieh Hsu from Harvard University and her team have figured out the biological reason why stress causes greying of the hair. Published in Nature, the team used experiments with mice to look at how stress affects stem cells in hair follicles. Most people have about 100,000 hair follicles on their head. The follicles are responsible for making melanocytes, the cells that give hair its natural color. As a normal part of the ageing process as people age, melanocyte production is reduced. This causes a person’s hair to begin turning grey naturally.

To make the connection between stress and greying of hair, the researchers suspected that an immune attack caused by a stressful event might be targeting the melanocyte stem cells. That theory, however, turned out to be false. The mice lacking immune cells still showed signs of greying hair.

Next, the team also thought the hormone cortisol, which always increases in the body during times of stress, might be a likely cause. However, when researchers removed the gland (adrenalectomy) that produces the cortisol hormones, the hair of mice still turned grey.

The team then focussed on the sympathetic nervous system. The sympathetic nervous system is key to all of the critical body processes that automatically happens in our body—our heart rate, our breathing, as well as things like digesting food and fighting off germs. It is also responsible for the” fight-or-flight response” which enables us to recognize and respond to threats before we really have time to think about and process them. In their experiments, when the mice were subjected to short-term pain or placed in stressful laboratory conditions, the SNS released a chemical called norepinephrine. Norepinerphrine then flowed through the stem cells up into the hair follicles where melanocytes are located. The researchers found that when the norepinephrine was released, all the melanocyte stem cells were highly activated and changed into pigment-producing cells. This overproduction process resulted in depletion of color-producing cells. Once the cells are gone they cannot be regenerated. So these experiments prove that stress is bad. If this is the effect it has on our hair follicles we can only imagine the damage it causes to all other cellular processes in the body. This research is promising because understanding the impact of stress on tissues can eventually lead to therapeutic innovations, which, might one day reverse or halt its detrimental effects.