Introduction: Observational studies have reported inconsistent results on the relationship between age-related macular degeneration (AMD) and Alzheimer's disease (AD). Therefore, we aimed to determine whether there is a causal association between AMD and AD.
Methods: This two-sample bidirectional Mendelian randomization (MR) study evaluated causal associations between advanced AMD and AD using summary data from large genome-wide association studies.
Results: Genetic liability for advanced AMD showed no statistical causal association with AD risk (odds ratio [OR] = 0.999, 95% confidence interval [CI]: 0.955-1.044, P = .948). Reverse MR analysis provided little support for a causal effect of AD on advanced AMD (OR = 0.973, 95%CI: 0.938-1.008, P = .133).
Discussion: This MR study found no evidence to support a bidirectional causality between advanced AMD and AD.
Highlights: We evaluated the bidirectional causal relationship between advanced AMD and AD. Advanced AMD showed no statistical causal association with risk of AD. We found no evidence to support a causal effect of AD on advanced AMD risk. The associations observed in epidemiological studies should not be considered causal.
Keywords: Alzheimer's disease; Mendelian randomization; age-related macular degeneration.
© 2022 the Alzheimer's Association.