The Aberdeen Birth Cohort 1936 (ABC1936) is a longitudinal study of cognitive ageing. All participants were born in 1936 and had completed a version of the MHT test of general intelligence in the Scottish Mental Survey 1947 at mean age 11 years14,23. Their recruitment and re-testing in old age has been described previously14,15. A total of 498 relatively healthy participants (243 men, 255 women) was traced and tested at mean age 64.6 years (SD = 0.9). The cognitive tests carried out were: the NART22, Raven’s Standard Progressive Matrices19, the Rey Auditory Verbal Learning Test20, Digit Symbol and Block Design sub-tests of the Wechsler Adult Intelligence Scale-Revised25, and the Uses of Common Objects Test22. Following informed consent, venesected whole blood was collected for DNA extraction. Ethical approval for all projects was obtained from the Grampian Research Ethics Committee.
