It is already believed that stress can promote the appearance of gray hair. Although the graying of hair is usually permanent, in a new study, however, scientists have shown that this process is reversible if it is caused by stress.
It is well-documented that stress causes the graying of hair. This common assumption was verified in mice in a 2020 study published in Nature. The depigmentation of the hair is due to the disappearance of melanocytes, the cells that carry melanin, which gives color to the hair.
Hair is born from the bulb, the living part, which is very energy intensive. Outside the bulb, the hair is considered dead, frozen in the state in which it left the bulb. A bit like the rings of a tree that preserve the traces of its environment. So a stressful situation could change the pigmentation of the hair, as would drought in the case of tree rings.
An international team of researchers developed a technique to accurately analyze depigmentation patterns in human hair. They then observed an amazing phenomenon: depigmented hair can regain its color! They published their work in eLife.
Gray hair can get its color back
The study was conducted on volunteers of all ages, genders, and ethnicities. The scientists took hair from the scalp, from roots to tips, and scanned it with a scanner to analyze color variations. Using this technique, they were able to determine that the depigmentation coincided with a period of stress as reported by the participants, and conversely, when the stress subsided, the hair regained its color. Thus, hair depigmentation is reversible.
The scientists also studied the proteins present in the pigmented and depigmented parts of the hair. They found that the white parts contained more proteins involved in energy production in the mitochondria responsible for hair growth. Other proteins associated with aging were also over-represented. Conversely, the depigmented parts contain less keratin. There also appears to be a stress threshold above which hair temporarily loses its color.
Scientists have not yet figured out the nature of this aging of the hair and in which cells of the hair bulb it occurs.
References
Quantitative mapping of human hair greying and reversal in relation to life stress
