1. From the Department of Epidemiology and Preventive Medicine (L.R.M., B.D.M.), University of Maryland School of Medicine, Baltimore, Md; the Centers for Disease Control and Prevention (W.G.), Atlanta, Ga; the VA Maryland Health Care System (J.C., M.W., S.J.K.), Baltimore, Md; the Department of Neurology (J.C., M.W., B.S., S.J.K.), University of Maryland School of Medicine, Baltimore, Md; and the Department of Medicine (B.D.M.), University of Maryland School of Medicine, Baltimore, Md.