Twin study identifies factors associated with skin aging

Long-term exposure to the sun causes physical and structural changes to the skin, resulting in photodamage, according to background information in the article. Unlike typical skin aging, which is characterized by the development of fine wrinkles and skin growths, photodamage includes characteristics such as coarsely wrinkled skin, spots of extra pigment or lost pigment and dilated blood vessels on the face. Sun damage also has been associated with the development of cancerous growths. Up to 40 percent of aging-related changes are due to non-genetic factors.

To identify some of these environmental factors, Kathryn J. Martires, B.A., of Case Western Reserve School of Medicine, Cleveland, and colleagues studied 65 pairs of twins attending the 2002 annual Twin Days Festival in Twinsburg, Ohio. A total of 130 individuals completed surveys collecting information about skin type, history of skin cancer, smoking and drinking habits and weight. Clinicians assigned each participant a photodamage score, graded by such characteristics as wrinkling and change in pigmentation.

Photodamage scores were highly correlated among both monozygotic (identical) and dizygotic (fraternal) twins. Other factors associated with higher levels of photodamage included a history of skin cancer, heavier weight and smoking, whereas alcohol consumption was associated with lower photodamage scores.

"The Twins Days Festival provides a rare opportunity to study a large number of twin pairs to control for genetic susceptibility. Among the most important results is that a history of skin cancer and photodamage are highly associated in a population that shares genetic commonalities," the authors conclude. "The relationships found between smoking, weight, sunscreen use, skin cancer and photodamage in these twin pairs may help to motivate the reduction of risky behaviors."