All 1091 subjects were interviewed and tested individually by a trained psychologist and a research nurse at the Wellcome Trust Clinical Research Facility at the Western General Hospital, Edinburgh. The interview, which included cognitive, physical and other tests, took place in a single visit to the Facility. The assessments that each subject undertook are now described in the order in which they were administered. There was a break of at least 15 minutes for refreshments. According to staff availability, the position of the physical testing section was varied for some subjects.
