Physiological system markers of aging.

Superficially physiological measurements and processes would appear to be excellent candidates to serve as biomarkers of aging. A considered analysis reveals that the validation of them as biomarkers of aging is difficult. The available evidence indicates that the concept of physiological age does not appear to be of much value. Although physiological measurements can serve as predictors of the future occurrence of age-associated diseases and as predictors of impending mortality, such predictors may be of little value as markers of the aging processes. It seems likely that physiological markers of aging can be validated only through the appropriate use of maximum life span and the knowledge base that must be obtained to do so is discussed.