Abstract
Background: Crohn's disease has been associated with the formation of Alzheimer's disease. In this study, we investigated the bidirectional causal relationship between Crohn's disease and Alzheimer's disease using a Mendelian randomization analysis.
Methods: A two-sample bidirectional Mendelian randomization analysis between Crohn's disease and Alzheimer's disease was performed using MR Egger, weighted median, simple mode, weighted mode, and inverse variance weighted regression algorithms. We focused on theinverse variance weighted analytical method. Subsequent sensitivity analyses were performed via a heterogeneity test, a pleiotropy test, and the leave-one-out method.
Results: The forward Mendelian randomization results revealed that Crohn's disease was causallyrelated to Alzheimer's disease (p = 0.0194), and Crohn's disease was a risk factor for Alzheimer's disease (b = 0.0109). There was no causal relationship between Alzheimer's disease and Crohn's disease based on the inverse variance weighted method applied to a reverse Mendelian randomization analysis, nor with the remaining four methods. The reliability of the results was confirmed the by the sensitivity analysis.
Conclusion: Our study supported a causal relationship between Crohn's disease and Alzheimer's disease. Crohn's disease was a risk factor for Alzheimer's disease without the influence of reverse causality. This study provides new ideas for further exploring the relationship between Crohn's disease and Alzheimer's disease. The information is relevant to the prevention of Alzheimer's disease.