The effects of continuous application of sunscreen on photoaged skin in Japanese elderly people – the relationship with the usage

Abstract

Since photoaging of skin is caused by chronic sun exposure, it is well-recognized that regular sunscreen use can help prevent photoaging of skin in fair-skinned people. Therefore, application of sunscreen is recommended for the prevention of photoaging in many countries. However, the relationship between UV exposure and photoaging has rarely been investigated in clinical studies in Japan. In addition, there have been almost no long-term interventional studies in Japanese people. We have previously conducted a study where Japanese actinic keratosis patients were instructed to continuously apply sunscreen. The results indicated that long-term application of sunscreen is effective in suppressing actinic keratosis progression and generation. In the present study, we investigated the effects of sunscreen on photoaged skin in 14 elderly Japanese people. Skin conditions such as water content, transepidermal water loss, the number of spots, wrinkles, and skin color tone uniformity were measured and compared before and after the study. A statistically significant difference was observed only in skin surface hydration. There were large inter-individual differences in amount of sunscreen used throughout the study. The changes in the number of spots and skin color tone uniformity during the 18 months showed good correlation with amount of sunscreen being used. These results suggest an increase in the number of spots and deterioration in skin color tone uniformity in the 18-month non-sunscreen application period, and that such skin conditions improved with increasing use of sunscreen. In this study, we suggested an inhibitory effect on photoaging symptoms such as spots and skin color tone non-uniformity, by application of the appropriate amount of sunscreen over a long period of time in Japanese people, similar to Caucasians.

Photoaging's portrait: The road map towards its photoprotection

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Defining skin aging and its risk factors: a systematic review and meta-analysis

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Awareness of sun exposure risks and photoprotection for preventing pigmentary disorders in Asian populations: Survey results from three Asian countries and expert panel recommendations

“…The effect of broad‐spectrum UVA and UVB sunscreen (SPF 30, PF 8) on photoaged skin was investigated in a 18‐month, single‐arm interventional study in 14 Japanese (7 men and 7 women) aged 62–91 years with FST II–III 71 . Despite receiving instructions on how to apply the sunscreen, large inter‐individual differences were observed in the amount of sunscreen used, ranging from 6.47 g/month to 63.7 g/month 71 . Improvements in uneven skin tone, area, and number of pigment spots showed a good correlation with amount of sunscreen used 71 .…”