rics, drug development, and drug use policy. The committee met twice during the course of the 10-month study and held a scientific workshop at Xavier University of Louisiana College of Pharmacy in April 1997. This report highlights the workshop presentations and summarizes the committee's conclusions regarding future research directions.

DEFINITIONS

A starting point in most discussions on aging populations is the definition of the terms aging and elderly. In cellular and animal models, aging is measured by replicative senescence or chronology (e.g., 40–50 replications of fibroblasts; 24–28 months of age in rats; 3–4 years in rabbits; and 8–10 years in dogs). Although gerontologists view human aging as a continuous process, no two individuals age in exactly the same manner; consequently there is considerable heterogeneity2 in the elderly population, with wide variance in physical health and cognitive function. However, for societal, demographic, and measurement purposes, there is a need to define the term elderly based on chronological age. Geriatricians and gerontologists often use the following construct to subdivide the population:

20–39 years

adult,

40–59 years

middle age,

60–74 years

young old,

75–85 years

old old, and

>85 years

very old or oldest old.

Diverse levels of physical health and overall well-being make it difficult to categorize what constitutes “normal aging.” Within each of the subgroups of people over 60 years of age, individual biological responses to aging are affected by a range of physiological, genetic, socioeconomic, and environmental factors including nutrition, access to medical care, smoking, and weight. Further, the over-60 subgroups vary widely in physical, emotional, and mental health, social function, activity levels, and overall vitality.

Definitional issues also surround the terms race and ethnicity. Although this report discusses aging issues related to race and ethnicity, particularly in elderly African-American populations, the committee acknowledges the complexities and limitations of racial categories. Individuals may be categorized into a particular group for purposes of identifying a study population; however, there may

2  

The elderly population encompasses a range of people including those who have aged successfully, those with few health conditions and risk factors, and those with health conditions and disability (Wenger, 1993).



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