"Androgenetic alopecia, a hereditary androgen-dependent disorder, is characterized by progressive thinning of the scalp hair defined by various patterns," the authors write as background information in the article. "It is the most common type of hair loss in men." Although risk for the condition is largely genetic, some environmental factors also may play a role.

Lin-Hui Su, M.D., M.Sc., of the Far Eastern Memorial Hospital, and Tony Hsiu-Hsi Chen, D.D.S., Ph.D., of National Taiwan University, Taipei, surveyed 740 Taiwanese men age 40 to 91 (average age 65) in 2005.
 

At an in-person interview, the men reported About smoking, other risk factors for hair loss and if they had alopecia, the age at which they began losing their hair. Clinical classifications were used to assess their degree of hair loss, their height and weight were measured and blood samples were provided for analysis.

The men's risk for hair loss increased with advancing age, but remained lower than the average risk among white men. "After controlling for age and family history, statistically significant positive associations were noted between moderate or severe androgenetic alopecia and smoking status, current cigarette smoking of 20 cigarettes or more per day and smoking intensity," the authors write.

This association could be caused by several mechanisms, they note. Smoking may destroy hair follicles, damage the papilla that circulate blood and hormones to stimulate hair growth or increase production of the hormone estrogen, which may counter the effects of androgen.

"Patients with early-onset androgenetic alopecia should receive advice early to prevent more advanced progression," the authors conclude.

Journal reference: Arch Dermatol. 2007;143(11):1401-1406.

Adapted from materials provided by JAMA and Archives Journals.

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