108 JOURNAL OF COSMETIC SCIENCE TtlE VEXING PROBLEM OF DRY SKIN Amy Zimmerman, Albert Kligman, Ph.D., and Fleming Anderson, Ph.D. Access Business Group, Ada, MI We all know what dry skin is ... don't we? Xerosis, "winter itch", rough, dry, cracked, scaly, itchy, frown lines of the forehead, laugh lines around the comers of the eyes, purse strings around the mouth. This common and annoying condition is caused quite simply when the skin cannot retain water. One of the most common symptoms of dry skin is itching or puritus, an unpleasant sensation that elicits a compelling desire to scratch. But WHY is dryness so common when we humans are almost 70% water? Why are young people as well as the elderly plagued with this problem? A comprehensive clinical evaluation to study the underlying causes and condition of dry skin was investigated, including the effects of both chronological and photoaging on xerotic skin. This study evaluated three distinctly different populations young, normal skin individuals ages 25-45, young xerotics and elderly xerotics ages 65 - 80 +. Clinical evaluations included visual grading, vascular responsiveness, susceptibility to chemical irritants, skin luminance, skin color, stratum comeum thickness, hydration, dansyl chloride extinction and photography. Visual grading was combined with a questionnaire, end evaluated scaling, roughness, visual dryness, and itching of the lower legs. The elderly had the worst scores for all measured parameters but most especially for itching. Vascular responsiveness was measured using methyl nicotinate (0.5%) and Laser Doppler. This provided an indication of the responsiveness of the microvasaculature and an indirect estimate of barrier function. The elderly showed a marked decline in Laser Doppler, while the young xerotic and normal were quite similar. Erythema induced as a asc u lar R esp o n siv en ess Laser Doppler Scan 450 400 350 300 •'= .... • 200 iso 10o 5 0 '• .... 0 "• B a selin e Young, Baseline Young, Baseline Elderly, Norm al X erosis X erosis result of the methyl nicotinate was most pronounced in the young xerotics. The xerotic elderly showed almost no response at all. Susceptibility to chemical irritation was measured several ways 24 hour patch tests with SLS and DMSO (dimethyl sulfoxide), clinical grading, TEWL, Comeometer, and Novameter. The results showed an overall reduction in reactivity to irritants and a decrease in TEWL with increasing age.

2002 ANNUAL SCIENTIFIC MEETING 109 Skin luminance and skin color were evaluated using a Chromameter. Redness, often a sign of inflammation was a measurement oferythema. There were no differences found between the three groups. There were unexpectedly high values in brightness with the young xerotics. The surface of their skin was uniformly covered with fine white scales. The elderly by contrast, was patchy and uneven yielding a low brightness value. Stratum corneum thickness was evaluated via shave biopsy. The horny layer was thickened in both xerotic groups. Average thickness in the elderly was 30+ layers, the young xerotics averaged 24 layers and the young normal have 18 or fewer layers. Skin hydration was measured via Corneometer, Novameter and via TEWL. The drier the skin the lower the Corneometer, and Novameter readings. The outer most corneocytes ofxerotic skin regardless of age are dried out, less hydrated and hold less water. They are brittle instead of soft and flexible. Dansyl chloride extinction of florescence results showed the elderly to be the first group to reach the point of patchy florescence, due to the large thick scales found on their skin. However the elderly were the last to reach final florescence extinction, due to the significantly slower rate of cell renewal. D a n sy 1 C h 1o rid e E x tin c tio n P a tte rn 30-• •ffilll P atc h y F Iou rescen ce l$ 1C om plete E xtin ction of Fluorescence 2 0 I 5 •.•:i ß ß ...., .. .:...:.........: .,:•. •... o ¾ o u n g, IN o rm a I ¾ o u n g, X erosis EIderly, X erosis This study helped to explain the biophysical differences ofxerotic skin with the young and elderly. Xerotic skin regardless of age showed little or no increase in redness when measured visually or with the chromamz.:er. This lack of redness indicates xerotic skin is not age dependant and is not an inflammatory condition. Laser Doppler studies showed a significant decline in the elderly. This decline is attributed to a reduction in blood vessels in the elderly. Fewer blood vessels result in a general lack of responsiveness to chemical irritants. Skin thickness increases with increasing age, clinically demonstrated by both a decrease in water loss as measured by TEWL and reduced reactivity to topical applied irritants. The elderly and the young xerotics showed and a decrease in skin hydration. Skin of both elderly and young xerotic groups was dried in appearanc, e and less hydrated•il'h a reduc, erl ahility to hold water• The harder function is compromised by the xerotic state regardless of age. Complete Dansyl Chloride extinction was slower for the young and old xerotics. This slower extinction rate indicates a thickening of the xerotic skin. The elderly rate however was much longer, attributable to the slower rate of cell renewal seen with age. Dry skin will continue as a vexing problem, but with continued studies such as this one, cosmetic chemists will be better able to provide long term effective relief.