1. From the Departments of Neurology (K.A.W., R.F.G.) and Epidemiology (R.F.G., A.W., A.L.G., E.S.), Johns Hopkins University, Baltimore, MD; Department of Neurology (D.S.K.), Mayo Clinic, Rochester, MN; Department of Medicine (T.H.M., B.G.W.), Division of Geriatrics, University of Mississippi Medical Center, Jackson.