Covariates included age at last assessment, sex, birth cohort, and the first 10 genetic ancestry principal components (PC1-10) in all analyses. Birth cohort was dummy coded using the generational cohort scheme from Bourdon et al. (2020): silent [b. prior to 1945]; baby boomer [b. 1946 to 1964]; generation X [b. 1965 to 1980]; and millennial [b. 1981 to 1996], with baby boomer set as reference.
