This cohort consists of 1091 relatively healthy individuals assessed on cognitive and medical traits at about 70 years of age. They were all born in 1936 and most took part at age 11 in the Scottish Mental Survey of 1947. They were Caucasian and almost all lived independently in the Lothian region (Edinburgh city and surrounding area) of Scotland. A full description of participant recruitment and testing can be found elsewhere (Deary et al., 2007). Genomic DNA was isolated from 1071 participants by standard procedure at the Wellcome Trust Clinical Research Facility (WTCRF) Genetics Core, Western General Hospital, Edinburgh. Twenty-nine samples failed quality control preceding the genotyping procedure. A reduced sample of 992 individuals had both genotype and phenotype data; their mean age was 69.55 years (SD = .84, range = 67.6–71.3 years) at data collection.
