1. From the Department of Neurology (S.D., A.B., R.A., J.J.H., M.K.-H., J.R.R., C.S.K., P.A.W., S.S.), Boston University School of Medicine, Boston, Mass; the Framingham Heart Study (S.D., A.B., R.A., J.J.H., M.K.-H., J.R.R., C.S.K., P.A.W., S.S.) and the Department of Biostatistics (A.B., J.J.H.), Boston University School of Public Health, Boston, Mass; and the University of California at Davis (C.D.), Sacramento, Calif.