Objective: To examine the separate and combined effects of depression and diabetes on the incidence of adverse health outcomes among older Mexican Americans.
Research design and methods: Longitudinal data from the Hispanic Established Population for the Epidemiologic Study of the Elderly (EPESE) survey were used to examine the main effects and interaction effects of diabetes and depressive symptoms (measured with the Center for Epidemiologic Study of Depression) or clinical diagnostic criteria (measured with the Composite International Diagnostic Interview Depression Module) on the development of macrovascular complications (including cardiovascular disease, stroke, and kidney disease), microvascular complications (including nephropathy, neuropathy, retinopathy, and amputations), functional disability, and mortality over 7 years in a sample of 2,830 Mexican Americans aged >or=65 years.
Results: The interaction of diabetes and depression was found to be synergistic, predicting greater mortality, greater incidence of both macro- and microvascular complications, and greater incidence of disability in activities of daily living, even when controlling for sociodemographic characteristics such as sex, age, education, acculturation, and marital status. Importantly, this interaction was found to predict not only greater incidence but also earlier incidence of adverse events in older adults.
Conclusions: Whether a marker for underlying disease severity, an indicator of diminished self-care motivation, or the result of physiologic changes, the interaction of depression and diabetes has a synergistic effect on the health of older Mexican Americans, increasing the risk for poor outcomes. This is of particular clinical importance because although depression is often underrecognized in older adults, effective treatment is available and can result in improved medical outcomes.