PRICE OF ADAPTATION - ALLOSTATIC LOAD AND ITS HEALTH CONSEQUENCES - MACARTHUR STUDIES OF SUCCESSFUL AGING

Background: Exponential growth in the population of older adults prese nts clinicians with special concerns about factors affecting risks for declines in cognitive and physical functioning. Objectives: To examin e the hypothesis that risks for such declines and for disease outcomes , such as cardiovascular disease, are related to differences in allost atic load, the cumulative physiologic toll exacted on the body over ti me by efforts to adapt to life experiences. To present an operational definition of allostatic load, along with preliminary evidence of its predictive validity in relation to salient outcomes of aging. Methods: Data from a longitudinal, community-based study of successful aging w ere used to develop a measure of allostatic load based on 10 parameter s reflecting levels of physiologic activity across a range of importan t regulatory systems. Allostatic load is the sum of the number of para meters for which the subject was rated in the highest-risk quartile. R esults: Higher allostatic load scores were associated with poorer cogn itive and physical functioning and predicted larger decrements in cogn itive and physical functioning as well as being associated with an inc reased risk for the incidence of cardiovascular disease, independent o f sociodemographic and health status risk factors. Conclusions: Findin gs are consistent with the conceptualization of allostatic load as an index of wear and tear on the body, with elevations in allostatic load predicting an increased risk for a decline in cognitive and physical functioning as well as cardiovascular disease in a cohort of older men and women. From a clinical perspective, the concept of allostatic loa d may provide the basis for a more comprehensive assessment of major r isks in the aging process.