Depression and disability in late life: directions for future research.

The author reviews evidence from epidemiologic and clinical studies suggesting a reciprocal, potentially spiraling, relationship between depression and disability in older adults. The discussion outlines possible methodological and conceptual explanations for this evidence and poses avenues for future research. An underlying theme is the impact of how disability and depression are measured on the nature of empirical evidence and its interpretation. Measures and corresponding analytic strategies that capture the complexity of depression, disability, and their relationship are expected to lead to the most fruitful approaches to reducing the burden of depression and disability in the lives of older adults.