Dry skin, barrier function, and irritant contact dermatitis in the elderly.

Dry skin is characterized by a decreased lipid content and a delayed reconstitution of the epidermal barrier after skin irritation. These are problems of high relevance in the aged population, especially in the development of irritant contact dermatitis. Asteatotic and perineal irritant dermatitis are the most important subtypes of irritant contact dermatitis in the elderly. This contribution presents a compressed survey on these subtypes and elucidates their relation to an impaired barrier function. Typical irritants affecting aged individuals are explained and compared with irritants that seem to be more significant in younger people. Results of biophysical investigations, such as measurement of transepidermal water loss, are discussed regarding their age-dependence. Transepidermal water loss decreases with age, which was formerly interpreted as an indication of a decreased sensitivity. Today, we know that reconstitution of the epidermal barrier after irritation is delayed once it has been impaired. Reasons are decreased activities of enzymes involved in lipid synthesis and processing, a changed cytokine profile, a reduced acidification of aged skin, and alterations in the function of epidermal stem cells. Owing to these new insights, a reevaluation of the sensitivity of aged skin has to be initiated, especially with regard to occupational dermatology.