Review of selected databases of longitudinal aging studies.

One of the recommendations of the 2010 Leon Thal Symposium, organized to develop strategies to prevent Alzheimer's disease, was to build a global database of longitudinal aging studies. Although several databases of longitudinal aging studies exist, none of these are comprehensive or complete. In this article, we review selected databases of longitudinal aging studies. We also make recommendations on future steps to create a comprehensive database. Additionally, we discuss issues related to data harmonization.