Details of cohort selection, risk factor assessment, and outcome determination in the 6 studies have been reported previously (Appendix, Section 1). Briefly, the AGES-Reykjavik Study is a single center prospective continuation of the Reykjavik Study, which included persons born 1907–1935 and living in Reykjavik, Iceland in 1967, when the study was started. In 2002–2006, 5764 participants from the cohort were reexamined as a part of the AGES-Reykjavik Study.9 The ARIC study enrolled adults aged 45 and 64 years, from 4 U.S. communities (N=15,792, including 11,478 whites). The baseline examination was in 1987–1989.10 The ASPS enrolled 2007 inhabitants of Graz, Austria who lacked neuropsychiatric disease. Between 1991–1994 and 1999–2003, an extended diagnostic work-up including neuroimaging was done in a subset of participants aged 45 to 85 years.11,12 The CHS enrolled adults who were 65 years or older and from 4 U.S. communities (N=5,888 including 4,925 whites). The baseline examination was either in 1989–90 or 1992–93.13 The FHS is a U.S.-based single-site study that comprises 3 generations of participants. Members of the Original cohort followed since 1948 (N=5,209)14,15 and the Offspring cohort
