State-of-the-art in longitudinal studies on aging: an overview of the supplement.

The articles in this supplement are based on a conference held in January 2008 sponsored by a grant from the Robert Wood Johnson Foundation. The purpose of the conference was to summarize major findings and methodological issues in previous and ongoing longitudinal studies on aging and to identify potentially fruitful areas for future research. This article is a review and synthesis of the articles in this supplement. Each of the articles makes important contributions to summarizing existing research, identifying challenging methodological issues, or proposing areas that should be explored in future research. Three themes were identified: general improvement in the health status of the population aged 65 and older in the United States, a shift in longitudinal research on aging from a focus on the endpoints of disease to a focus on the preclinical stage and underlying mechanisms of these diseases, and contemporary developments in longitudinal research methodology. A number of practical suggestions were also drawn from the articles reviewed.