Skin Aging: A Brief Summary of Characteristic Changes

Abstract

Life expectancy in industrialized countries has consistently increased in the last few decades and is predicted to be a continuing process. Like any other organ, the human skin ages and undergoes clearly distinguishable changes due to aging. In aging skin, cell replacement is continuously declining, the barrier function and mechanical protection are compromised, wound healing and immune responses are delayed, thermoregulation is impaired, and sweat and sebum production are decreased. It is evident that environmental factors as well as genetic programs contribute substantially to the processes involved. The long-term exposure of skin to solar UV radiation leads to “photoaging” or “extrinsic” aging and clinically manifests as rough skin textures, wrinkles, laxity, atrophy, pigmentary changes or blotchy dyspigmentation, elastosis, telangiectasia, and precancerous lesions such as actinic keratosis and malignant tumors. In contrast, “intrinsic” aging is genetically determined and characterized by fine wrinkles, a thin and transparent appearance, loss of underlying fat leading to hollowed cheeks and eye sockets, dry and itchy skin, and inability to perspire sufficiently, hair graying, hair loss or hirsutism, and thinning of nail plates. However, both processes may overlap, and the underlying mechanism of both processes is increased oxidative stress, which is probably the single most harmful contributor to skin aging.