Mendelian randomization analysis of the effect of plasma homocysteine on AD risk using individual participant data (plasma homocysteine polygenic score association study). Estimates for the effect of 1-standard deviation increase in plasma homocysteine polygenic score on AD risk (OR and 95% CI) while accounting for the effects of age, sex, and APOE ε4 allele status are demonstrated for each study/imputation batch (dark blue). The overall result from the mega-analysis is shown in black. Abbreviations: AD, Alzheimer’s disease; CI, confidence interval; CN, cognitively normal; OR, odds ratio.