The LBC1921 is a longitudinal study of cognitive ageing. All participants were born in 1921 and completed the Moray House Test (MHT) No. 12 assessment of general intelligence in the Scottish Mental Survey 1932 at a mean age of 11 years14,18. Their recruitment and re-testing in old age has been described previously14,15. Relatively healthy surviving participants of the Scottish Mental Survey 1932 were identified within Edinburgh and its surrounding area, the Lothians. A total of 550 individuals (234 men and 316 women) were recruited and tested at a mean age of 79.1 years (SD = 0.6)15. The LBC1921 participants were tested individually and completed a battery of cognitive tests: The Moray House Test No. 12 (MHT)18, Raven’s Standard Progressive Matrices19, Verbal Fluency20, and Logical Memory21. Participants also completed the National Adult Reading Test (NART)22. Following informed consent, venesected whole blood was collected for DNA extraction. Ethical approval for all projects was obtained from the Lothian Research Ethics Committee.
