Gray
hair and age
The first onset of gray hair and the speed at which people go gray
varies considerably from person to person. Most people actually
start going gray in their late 20s but they don't notice it immediately.
Premature graying is defined as gray hair onset before late teens
for Caucasians and before age 30 in Africans and Asians, or alternatively
50% or more gray scalp hair before age 50. Very occasionally, a
few gray hairs can develop in children as young as 8 years and yet
it indicates nothing other than an early onset of the gray hair
that we all develop with increasing age. Typical gray hair first
develops at age 34.2 +/- 9.6 years in Caucasians while for Black
people the average age of onset is 43.9 +/-10.3 years (Keogh 1965).
As a rough guide, 50% of the population in the US and Europe have
50% gray hair by age 50.
The most common areas on the scalp in which to first see gray hair
development are above the ears and/or at the temples. This first
gray hair may spread around the sides and to the crown with time.
Gray hair development in the beard and mustache may also start quite
early, while gray hair on the chest and pubic region generally only
occurs some years after onset of gray hair on the scalp.
Gray hair is caused by the gradual reduction of melanin production
over time within the affected hair follicle. The melanocytes in
the hair follicles produce less and less melanin, and the result
is a loss of hair fiber color strength. What we call gray hair is
not gray at all if you look at the individual hair fibers. Some
hair fibers will contain some color while others are virtually white.
What we describe as gray comes about from our perception of the
overall scalp hair color. The contrast between the hair with more
color and the white hair causes the appearance we call gray hair.
Thus two people with gray hair, standing side by side, may have
different shades of gray. Blondes are most likely to develop a completely
white head of hair in old age because their hair fiber has a very
low density of pigment in it to start with.
The time and speed of gray hair onset is due in part to genetics.
Certainly early onset gray hair development can run in families.
In my own family women are invariably affected by early and rapid
onset gray hair while men have a more typical gray hair development.
This difference in gray hair development in my family might suggest
that at least some of the genes that promote early gray hair onset
are located on the X chromosome. However, there are most likely
many genes that determine the time and speed of gray hair development
located on several human chromosomes. What genes determine gray
hair is not known and much research needs to be done in this area.
The environment may also potentially modify gray hair development
but there is effectively no research on this subject.
Gray
hair and age references
- Tobin DJ,
Paus R. Graying: gerontobiology of the hair follicle pigmentary
unit. Exp Gerontol. 2001 Jan;36(1):29-54.
- Nagl W. Different growth rates of pigmented and
white hair in the beard: differentiation vs. proliferation? Br
J Dermatol. 1995 Jan;132(1):94-7.
- Takada K, Sugiyama K, Yamamoto I, Oba K,
Takeuchi T. Presence of amelanotic melanocytes within the outer
root sheath in senile white hair. J Invest Dermatol. 1992 Nov;99(5):629-33.
- Nanninga PB, Ghanem GE, Lejeune FJ, Bos
JD, Westerhof W. Evidence for alpha-MSH binding sites on human
scalp hair follicles: preliminary results. Pigment Cell Res. 1991
Oct;4(4):193-8.
- Thomas J, Prabhavathy D, Augustine SM,
Muthuswami TC. Absence of graying of pinnal hairs. Arch Dermatol.
1989 Nov;125(11):1589.
- Ortonne JP, Thivolet J, Guillet R.Graying
of hair with age and sympathectomy. Arch Dermatol. 1982 Nov;118(11):876-7.
- Stankler L, Bewsher PD. Rapid whitening
of scalp hair. A manifestation of localized ageing in a healthy
man. Practitioner. 1980 Nov;224(1349):1168-70.
- Leguebe A, Twiesselmann F. [Variations
of hair color according to age] Z Morphol Anthropol. 1976 May;67(2):168-80.
- Meyer-Konig L. [Age changes in eye and
hair color, a longitudinal study]. Anthropol Anz. 1975 Oct;35(1):24-41.
- Ronchese F. A comment
on uneven whitening of senile hair. Int J Dermatol. 1974 Mar-Apr;13(2):84-5.
- Shubert S. Premature
greying of the hair. Lancet. 1972 Nov 4;2(7784):979.
- Naruse N, Fujita T. Changes in the physical
properties of human hair with age. J Am Geriatr Soc. 1971 Apr;19(4):308-14.
- Flugel B. [The graying of hair as a criterion
of biological age] Z Alternsforsch. 1971;23(4):397-400.
- Herzberg J, Gusek W. [The greying of hair.
Histochemical and electronmicroscopical investigations] Arch Klin
Exp Dermatol. 1970;236(4):368-84.
- Orfanos C, Ruska H, Mahrle G. [White hair
in older people. IV. Fine structure of human hair]. Arch Klin
Exp Dermatol. 1970;236(4):395-405.
- Keogh EV, Walsh RJ. Rate of greying of
human hair. Nature. 1965 Aug 21;207(999):877-8.
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