Is skin ageing in the elderly caused by sun exposure or smoking?

BACKGROUND: There is little clear evidence of a strong association between cumulative sun exposure and skin wrinkling. Contradictory findings also exist on the association between facial wrinkling and smoking status. OBJECTIVES: To identify the significant determinants of skin wrinkling in a cohort of older subjects and to assess whether skin wrinkling can be used as an objective measure of cumulative sun exposure. METHODS: This study was carried out in the South Glamorgan health district, Wales, U.K., between 1988 and 1991. A random sample of 792 older subjects (60 years and over) was obtained from the Health Authority register of patients registered with general practitioners. A range of phenotypic and environmental data was collected during a home visit by interview and examination by an experienced dermatology research fellow. Skin wrinkling/ageing was assessed by examining the face, neck and dorsum of the hand and scored on a 10-point ordinal scale. Cumulative sun exposure was assessed by asking subjects to estimate their average outdoor time during each of three periods of adult life. This measure showed acceptable repeatability (r = 0.64 for estimates obtained 1.4 years apart). RESULTS: The response rate was 71% and the mean age of participants was 71 years. The mean +/- SD skin ageing score was 5.5 +/- 1.5. In multiple logistic regression models only age and daily cigarette consumption were significantly associated with skin ageing. Cumulative sun exposure was significant on univariable analysis but this effect was removed by adjusting for age. Smoking 20 cigarettes per day was equivalent in effect to almost 10 years of chronological ageing. CONCLUSIONS: Smoking is an important determinant of macroscopic skin ageing/wrinkling in older subjects. This evidence suggests that skin ageing does not clearly provide an objective measure of cumulative ultraviolet exposure, and caution should be exercised before it is used in this way. The association between smoking and wrinkling provides important information for potential use in education campaigns to reduce smoking prevalence among young people.