We used the Health and Retirement Study27 (HRS) and the National Longitudinal Study of Adolescent to Adult Health (Add Health) as our prediction cohorts. We applied the same SNP filters as in the main MTAG analyses. Additionally, we restricted the set of SNPs used to construct the scores to HapMap3 SNPs for comparability across the two prediction cohorts. We calculated the SNP weights using the software package LDpred, assuming a fraction of causal SNPs equal to 1. The scores were constructed in PLINK using genotype probabilities obtained from 1000 Genomes imputation.
