Observing the onset of disability in older adults.

One of the greatest threats to the ability of older adults to live independently is the onset of disability in activities adults perform in their daily lives, such as dressing, eating, toileting, managing one's money, preparing meals and so on. This article examines the onset of disability in older adult Americans using three waves of the Asset and Health Dynamics Among the Oldest Old (AHEAD) survey (1993, 1995, 1998; n=4228). We use medical/demographic factors (arthritis, heart disease, diabetes; age, gender, race/ethnicity, wealth), baseline characteristics (affect, cognition, health behaviors, medical insurance), and time-varying covariates (changes in chronic conditions and baseline characteristics) to predict the onset of activities of daily living (ADLs) and instrumental activities of daily living (IADLs) disability, individually and in the aggregate, over time. We find the onset of ADL and IADL disability is a complex process, suggesting important roles for medical, demographic, social, psychological, and behavioral triggers, specifically negative affect, higher body weight, and by the lack of vigorous exercise. We also find that individual ADL and IADL impairments are predicted by a variety of different factors, suggesting that summary measures of disability may be masking a wealth of potentially useful interventions. In general, public health efforts in the area of controlling obesity and treating depressive symptoms should be supported.