Diagnosis: Gray hair associated with normal aging

A sign of normal aging, gray, silver, or white hair is simply hair that is lacking pigmentation and might even be considered transparent. The graying process generally begins at about age 30 in males and age 35 in females; by age 75, any hair a person has is mainly gray.

The development and amount of gray hair does not correlate with overall health. Degrees of graying, baldness, and facial wrinkles were not predictive of a shorter life span in 20,000 men and women in the Copenhagen City Heart Study.1

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Clinical presentation ranges from a few inconspicuous gray hairs to salt-and-pepper hair to silver-gray hair to lusterless hair. It may take 10-20 years for all the hair of a dark-haired person to turn gray. The most common treatment is hair dye.

Several pathologic states can result in gray hair. Alopecia areata (AA) can selectively lead to the loss of pigmented hairs such that salt-and-pepper hair turns gray overnight when loss of pigmented hairs leaves behind only gray and silver hairs. This may happen during periods of stress. In telogen effluvium (TE) (e.g., alopecia in stable hairs resulting from stress due to chemotherapy, severe illness, childbirth, high fever, medication use, or iron deficiency, particularly in women), hair that falls out can grow back gray.

A Talmudic figure in the Passover Haggadahs is said to have turned gray overnight before assuming high office, giving him an older, more serious appearance. The transformation was probably due to stress-related AA. The hair of Sir Thomas More and Marie Antoinette turned silver overnight. It is unclear if they had TE or AA. Sometimes in TE- and AA-induced graying, the pigment returns. Some reports have noted that TE-induced gray hairs grew back pigmented after completion of chemotherapy.

Imatinib mesylate (Gleevec), which affects tyrosine kinases important in pigment production, can turn hair gray and skin white. The flag sign (hair with bands of gray) results from nutritional deficiencies or certain medications. Most drug-induced changes result in lighter hair color, although p-aminobenzoic acid and some chemotherapy regimens have darkened hair.

Hair color results from different types of melanin (eumelanin for brown or black hair and pheomelanin for yellow or red hair) that is made in melanocytes. Functional melanocytes arise from colorless melanocyte stem cells. The melanin is stored in melanosomes and then transferred—first to hair-making keratinocytes and then to the hair. The graying process involves multiple defects in this process, including melanocyte depletion and malfunction.

Researchers have yet to come up with a unified theory for graying. A gross evaluation of graying patients revealed fewer hairs, fewer melanocytes, and smaller melanosomes. Some experts think free radicals damage the pigment-producing cells. The authors of one study linked graying to the gradual dying off of stem cell melanocytes or transformation of those cells to “pigment cells that position themselves in the wrong part of the hair follicle, thus leading to a loss of pigmentation.”2 Stem cell depletion also causes diminished hues. Another report notes that graying may be one consequence of depletion of bulb and outer root sheath melanocytes. 

Some researchers have found that gray-hair follicles still contain melanocytes and melanosomes but no melanin. One scientist has reported that dormant melanocytes and melanosomes can be tricked into making melanin again, but this development has yet to transform the hair-coloring industry.

We told our patient that it was perfectly acceptable from a medical standpoint to dye her hair.

Dr. Scheinfeld is assistant clinical professor of dermatology at Columbia University in New York City, where he has a private practice.

1. Schnohr P, Lange P, Nyboe J, et al. Gray hair, baldness, and wrinkles in relation to myocardial infarction: the Copenhagen City Heart Study. Am Heart J. 1995;130:1003-1010.
2. Nishimura EK, Granter SR, Fisher DE. Mechanisms of hair graying: incomplete melanocyte stem cell maintenance in the niche. Science. 2005;307:720-724.