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Gray Hair Signals Battered DNA

from ScienceNOW Daily News

If you've ever blamed your gray hair on stress, you weren't far from the truth. Genotoxic stress--the kind that can damage a cell's DNA--causes hair to whiten over time, according to a new study.

The results challenge accepted ideas about how stem cells age and may eventually lead to new ways to prevent graying and treat the more serious conditions caused by genotoxic stress, such as cancer.

For hair, life is simple. A strand grows for several years, then rests for 2 to 3 months before eventually dying and falling out. In 2004, Emi Nishimura, a dermatologist now with the Tokyo Medical and Dental University in Japan, linked this process to the hair follicle's melanocyte stem cells.