Photoaging's portrait: the road map towards its photoprotection.

Abstract

To summarize key research published by the author's group, dealing with skin photoaging and its photoprotection. Two methodologies (standard photographs and selfies imaging) resulting from referential skin aging atlases were applied on 2487 subjects of different ancestries, ages, and gender. These aimed at first to best assess and grade the variable severities of some facial signs (texture/wrinkles, pigmentary spots, sagging, vascular disorders) that occur progressively during the photoaging process. Second, such methodologies were used to record the benefits brought by a photoprotective regimen (671 women and men). In all studied ancestries, each facial sign show an increase severity along decades, at its own pace, some showing a linear like progression whereas some plateau at early ages. These changes differed according to skin innate color (phototype) and with individual behaviors vis à vis sun exposures, more so among European women than North-East Asian women. An effect of gender (less severe alterations) was observed on Chinese men, as compared to Chinese women. Pigmentary disorders were found hallmarks of photo-aged North-East Asian women. Globally photoaging impact the apparent age of the different subjects. The counteracting effects of strong topical Photoprotective regimens were evidenced along a 6-month seasonality in Chinese and Caucasian women or 1-year period in Brazilian women with phototypes II to VI. Photoprotection led to a more even skin complexion among Indian subjects with pigment irregularities. Two factors clearly hamper a better assessment of the efficiency of photoprotection of the sun-induced cutaneous aging: short durations (months) of the studies with regard the global fate of photoaging by decades and the number of studied subjects, limited to hundreds for practical reasons. The methodology based on the automatic analysis of facial signs through selfies images could theoretically by-pass both factors, allowing thousands of subjects to be studied along years.