Hair rightly called the crown of the body, plays an instrumental role in maintaining a positive societal and self-perception of an individual. Gray hair is usually associated with physiological aging and is often seen as a sign of senescence. For this reason, graying of hair prematurely can adversely affect the self-esteem of young individuals, especially the ones with darker hair types due to the easy visibility of gray hair because of high contrast, where few gray strands tend to be immediately noticeable.
Hair graying is either physiological or pathological, the latter being premature most of the time. There is a definite racial variation in the occurrence of physiological aging. The traditional 50/50/50 rule of hair graying says that by the age of 50 years, 50% of the population will have 50% black hair. In a more recent large survey, however, Panhard et al. reported that only 6–23% of people have 50% hair by the age of 50 years.
The term premature hair graying (PHG) is generally used in different literature reviews when the onset of graying is before the age of 20–25 years in Caucasians, 25–30 years in Asians including Indians, and late 30’s in Blacks. PHG is determined by genetic factors, i.e., hypothesized to be inherited as an autosomally dominant trait environmental factors, and can also be seen in nutritional disorders, or pathological conditions such as osteopenia, and cardiac disorders among others. Quite a few genetic, acquired, and autoimmune disorders are also associated with canities.
Even with the increasing understanding of pathogenesis and ultrastructure of graying hair, the exact underlying cause for its premature onset is not very well understood, and hence a satisfactory treatment for its reversal as of today seems elusive.