The causal association between the new gut microbiota and Alzheimer's disease: A Mendelian randomization study

Apr 3, 2026Journal of Alzheimer's disease reports

Possible links between new gut bacteria and Alzheimer's disease

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Abstract

Fourteen specific gut microbiota are associated with the risk of Alzheimer's disease.

Certain gut bacteria may reduce the risk of Alzheimer's disease.
Other gut bacteria could increase the risk of Alzheimer's disease.
The analysis utilized genetic data from 473 gut microbiota species linked to Alzheimer's disease.
No horizontal pleiotropy was detected, indicating stable associations.
Findings contribute to understanding the gut-brain connection related to Alzheimer's disease.

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BACKGROUND: There is a need for more studies to validate the role of gut microbiota in Alzheimer's disease (AD).

OBJECTIVE: This study aims to explore the causal association between new gut microbiota and AD using .

METHODS: Using genome-wide association study (GWAS) of 473 gut microbiota species and AD in IEU Open GWAS database, independent genetic loci related to gut microbiota were extracted as instrumental variables. The inverse variance weighting method was employed as the main indicator for evaluation. The stability and reliability of the results were further verified by heterogeneity test, outlier detection, horizontal pleiotropy test and leave-one-out analysis.

RESULTS: Following a thorough screening process, a total of 14 intestinal microbiota were included in the final analyses. The elevated abundance of,,,,, andcan reduce the risk of AD. Higher abundance of,,,,,,, andcould increase the risk of AD. The MR-Egger analyses at 14 "genus" levels showed no horizontal pleiotropy and the p values were all more than 0.05. The leave-one-out analysis showed that results were relatively stable. Agathobacter Citrobacter A Clostridium E sporosphaeroides Eubacterium R Megamonas funiformis Pseudomonas aeruginosa Bifidobacterium Holdemania massiliensis Hydrogenophaga Intestinimonas massiliensis Megasphaera Paenibacillus J Prevotella Raoultella

CONCLUSIONS: This study revealed a causal relationship between 14 specific gut microbiota and the risk of AD occurrence. Some bacteria are protective, while others increase the risk of AD. These findings are of clinical significance for the treatment and prevention strategies in clinical practice, and it also provides new perspectives for related research on the "".

Key numbers

Causal Relationship Count

Total gut microbiota analyzed for association with AD

111,326 AD patients

Sample Size for AD Analysis

Number of Alzheimer's disease patients in the GWAS study

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The causal association between the new gut microbiota and Alzheimer's disease: A Mendelian randomization study

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