Cohen, Gene D. Formerly, National Institute on Aging, National Institutes of Health, Bethesda, Maryland.
Last reviewed:June 2019
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- Aging versus illness
- Theories of aging
- Life extension
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An age-contingent reduction in physiological function and activity, with a concomitant increase in mortality rate and a diminution in reproductive rate. Aging is the process of becoming older, which is influenced by genetic and environmental factors. However, definitions of aging differ between biologists and behavioral scientists. Biologists regard aging as reflecting the sum of multiple and typical biological decrements occurring after sexual maturation; in contrast, behavioral scientists view it as reflecting regular and expected changes occurring in genetically representative organisms advancing through the life cycle under normal environmental conditions. It is difficult to define normal aging because many changes observed in older adults and perceived as concomitants of normal aging are effects of disease in later life. The behavioral science view allows for incremental as well as decremental changes with aging. Senescence is not always equated with aging; it is viewed as the increasing vulnerability or decreasing capacity of an organism to maintain homeostasis as it progresses through its life span, leading to death (Fig. 1). Gerontology refers to the study of aging. Geriatrics refers to the clinical science that is concerned with health and illness in the elderly. See also: Cell (biology); Cell senescence; Death; Genetic influences on aging; Genetics; Human genetics
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