QUANTITATIVE-EVALUATION OF CHRONOLOGICAL AGING AND PHOTOAGEING IN-VIVO - STUDIES ON SKIN ECHOGENICITY AND THICKNESS

Skin ageing is divided into chronological ageing and photoageing due t o the cumulative effects of solar ultraviolet radiation. It is, howeve r, difficult to measure the degree of photoageing and chronological ag eing in humans in vivo. Here, we have evaluated the usefulness of ultr asonography for measurement of chronological ageing and photoageing in vivo. Twenty megahertz ultrasonography was performed in 90 individual s (29 men, 61 women, age 18-94) to describe age-related changes in sun -exposed regions with different levels of sun exposure (dorsal and ven tral forearm, forehead, ankle) and non-exposed buttock skin. Skin thic kness and skin echogenicity in different layers of the dermis were mea sured in ultrasound images. Additionally cutaneous photodamage was sco red clinically. Age-related changes were dependent on body site as wel l as layer of the dermis. A progressive, age-related decrease in echog enicity of the upper dermis was found in sun-exposed regions (dorsal f orearm, forehead), but not in moderately exposed regions (ventral fore arm, ankle). In the buttock. an increase in echogenicity was observed. The echogenicity of the lower dermis increased in all examined sites. Skin thickness increased with age in the forehead and buttock, but de creased in the extremity skin. Our findings show that photoageing caus es a decrease in echogenicity in the upper dermis. In contrast, chrono logical ageing is associated with an increase in echogenicity in the l ower dermis. Although both increases and decreases in skin thickness w ere observed in different anatomical regions, there was no general rel ationship between skin thickness and age. Dermal echogenicity was deem ed valuable for in vivo study of chronological ageing and photoageing.