The study is sponsored by the National Institute on Aging and is being conducted at the Roskamp Institute in Tampa, FL; the Veterans Affairs Puget Sound Health Care System with the University of Washington, in Seattle, WA; Boston University School of Medicine, in Boston, MA; the Johns Hopkins Medical Institutions, in Baltimore, MD; Sun Health Research Institute, in Phoenix, AZ; and the University of Rochester, in Rochester, NY. At each of these six sites, the goal is the enroll approximately 700 men and women, totalling 2,625 participants. Participants must be 70 years of age or older, have a parent, brother, or sister who has, or had, serious age-related memory loss, senility, dementia, or Alzheimer's disease.