The effect of age on skin color and color heterogeneity in four ethnic groups.

BACKGROUND: Few comparative data are available on age-related changes in skin color among different ethnic groups. The aim of the study was to measure and analyze the skin color and color heterogeneity in four different ethnic groups living in the same local environment and to determine the effects of age on these skin color characteristics. METHODS: Female volunteers (385) from four ethnic populations (African-American, Caucasian, Chinese and Mexicans) living in the same city were enrolled after informed consent. Skin color was measured on two facial areas, forehead and cheek. The subjects were further divided into six age ranges: 19-30, 31-40, 41-50, 51-60, 61-70 and 71-87 years to determine any age-related effects on the skin color and color heterogeneity in both areas. RESULTS: According to the L(*)a(*)b(*) CIE system, clarity (fairness/lightness) was found to be lower in the African-American group whereas the hue was lower in Caucasians, which means more red skin. A clear, statistically significant darkening of the skin with age was observed in all ethnic groups, while evidence of yellowing of the skin was shown in the Chinese volunteers. Overall, the skin color of the face of African-Americans was more heterogeneous than in the other ethnic groups, but showed the least increase with age. CONCLUSION: Our study revealed interesting differences in skin color and color heterogeneity with respect to ethnicity and age-related alterations. Data obtained are very useful in improving our knowledge about the skin of people of different origins and helps in the development of specific cosmetic products that are well adapted to all these populations.

Skin from various ethnic origins and aging: an in vivo cross-sectional multimodality imaging study.

BACKGROUND: Ethnic differences in skin structural features have not been thoroughly investigated, and the few reported studies are contradictory. Thus, we have carried out a set of in vivo measurements on the skin of about 400 volunteers from various ethnic origins living in the same environment. METHODS: Female subjects were distributed into four ethnic groups: African Americans, Mexicans, Caucasians, and Chinese. Inter- and intra-ethnic skin structural differences, according to age and anatomic site, were investigated using three non-invasive skin-imaging methods: ultrasound (US) at 25 and 150 MHz, and optical coherence tomography (OCT). RESULTS: The thickness of the skin is higher on the cheek compared with the dorsal and ventral forearm, with no ethnic or age-related specificity. We confirm that the sub-epidermal non-echogenic band is a sensitive marker of skin aging, and reveal for the first time that it is less pronounced in African Americans. From OCT images, we bring out evidence that the thickness of the dermal-epidermal junction (DEJ) decreased with age, and was higher in African Americans than in Caucasians. Finally, by comparing US images at 150 MHz with OCT images, we show that papillary dermis thickness can be measured and appears to be quite constant irrespective of age or ethnic group. CONCLUSION: Our study confirms that skin imaging is very attractive to further our knowledge of the morphology of skin from various ethnic origins. Regarding age effects, quantitative parameters have shown that they would be delayed in African Americans compared with all other ethnic populations.

Comparative study of the hydration of the stratum corneum between four ethnic groups: influence of age.

BACKGROUND: Several recent overviews have reported that significant work remains to be performed to understand and quantify the ethnic differences in skin properties. In this way, we have carried out a set of in vivo biophysical experiments on the skin of American women from different ethnic populations living in the same environment. Inter- and intraethnic skin micro relief results were already published, skin hydration differences are now reported here. METHODS: The skin water content was evaluated taking advantage of the new skin capacitance imaging technique which allows to study stratum corneum hydration without suffering of the influence of the skin micro-relief and hair on the measurement. Three hundred and eleven American women from four ethnic groups were enrolled in this study. The investigation was performed during the summer season of 2004 on the major relatively distinct ethnic groups of Chicago, which is to say: African American, Chinese, Caucasian and Mexican. The hydration of the skin was investigated on the dorsal and ventral forearm sites as a function of ethnicity and age. RESULTS: Skin dryness is higher on sun exposed sites for lighter skin tones, such as in Chinese and Caucasian women, than on sites that are primarily out of the sun; while, no skin dryness differences are seen on either site for African American and Mexican women whose skin is darker. The skin dryness does not change as a function of ethnicity for the younger group for either the ventral and dorsal site of the forearm. With age, however, the dryness of the skin is higher for African American and Caucasian women than for the two other ethnic groups, with a higher percentage increase in Caucasian women. CONCLUSIONS: This study has revealed that the hydration of the skin is different according to ethnicity and that the age effects are influenced by ethnicity, suggesting anatomical or physiological property differences in ethnic skin. This study has also pointed out that the SkinChip seems to be a convenient and fast way to investigate both the micro relief as previously published and the dryness of the skin on a large number of subjects, and in this way will be very useful to improve our knowledge about skin of people from different ethnic groups and helping to develop specific products that are customized to all these populations.

Development and validation of a new Skin Color Chart.

BACKGROUND: Age-induced skin color variations are of great importance and incite increasing demand for cosmetic products to improve the appearance. The evaluation by clinicians or estheticians of the efficacy of skin care products is particularly difficult and requires the help of color charts. PURPOSE: To standardize this kind of evaluation, we have developed a new Skin Color Chart. In contrast to other color charts, this new one represents true skin color without metamerism and covers almost all skin colors encountered around the world. This new instrument has been validated for both Asian and Caucasian skin complexion and sun spot color. METHOD: The new device used to record skin color, the Chromasphere, developed by L'Oréal, is briefly presented. All skin color measurements and the validation of each selected Color were performed under identical conditions, and then, absorption spectra of both skin and chart were compared using severe criteria. The first use and the validation of this Skin Color Chart were performed by dermatologists (two in China and one in France) in groups of about 40 women on sunspots and complexion color. RESULTS: Regarding repeatability (intraobserver agreement), the new Skin Color Chart showed very good statistical validation on complexion and sunspot color. The agreement between dermatologists, the reproducibility criterion, although not as good remained high. An example of the evaluation of the efficacy of a whitening product is given in order to illustrate the 'sensitivity' of this new device to evaluate very weak color variations. CONCLUSIONS: The new Skin Color Chart appears to be very useful and easy to use even by clinicians without training in color evaluation.