1. Department of Neurology (Y.H., Y.K., M.I.), National Cerebral and Cardiovascular Center, Japan.
2. Department of Preventive Medicine and Epidemiology (E.K., S.O., K.N.), National Cerebral and Cardiovascular Center, Japan.
3. Turku PET Centre, University of Turku and Turku University Hospital, Finland (H.I.).