Physiologic changes in older skin

Clearly, like all other organ systems, the skin undergoes physiologic decline with advancing age. In the elderly, the stratum corneum may not be as capable of acting as a barrier. Once noxious substances penetrate, they are less likely to be rapidly cleared and often will not provoke integumental reactions or pain sensations that would serve as warning signals to the aged. Thus older individuals are not only more vulnerable to environmental insults but also fail to recognize that they are being adversely affected. As a result, these substances may accumulate following repeated exposure to the point that the threshold for clinical display is exceeded, whereas the threshold would never be reached in younger individuals. Thus it is not surprising that many of the common problems of the elderly are likely to represent subtle, chronic irritant dermatitis. Then, too, because cellular turnover and repair are much slower, the time to recover from such damaging insults is prolonged. In conclusion, I would like to stress that one of the most important observations to come out of our studies is that there exist cutaneous clues to an individual's physiologic age. It is generally appreciated that some elderly individuals seem to be much more youthful and other much older than their stated ages, suggesting that there may be a wide gap between chronologic and physiologic age. Indeed, one of the central concerns of gerontology is to develop methods by which physiologic aging can be monitored. We are certainly not the first to realize that the skin and its appendages may furnish useful markers of physiologic age. In fact, DuNuoy, who was the first to formalize the concept of physiologic age, did so on the basis of age-associated differences in cutaneous healing. By far the most comprehensive ongoing longitudinal study of human aging is that being conducted by the National Institute on Aging Gerontology Research Center at the Baltimore City Hospital. Although the integument was regretfully ignored, a saving grace of this study was the inclusion of a visual estimate of apparent age by the examining physician. This made it possible to determine whether individuals who looked older than their chronologic age were older physiologically. On 19 of the 24 tests, individuals in the subgroup who looked oldest for their age were physiologically older as well. Even more important was the finding that the subjects who had died since the start of the study were also apparently and physiologically older.(ABSTRACT TRUNCATED AT 400 WORDS)