Alzheimer's & dementia : the journal of the Alzheimer's AssociationJul 3, 2025

Gut bacteria types and functions linked to Alzheimer's disease changes

Alzheimers & Treatments Weekly Brief ↗PubMed ↗DOI ↗OA ↗

Updated Jan 3, 2026

Abstract

Gut microbiome composition and function differ between individuals with Alzheimer's disease (AD) dementia and those who are cognitively unimpaired.

Distinct gut microbiome features were identified between AD dementia patients and cognitively unimpaired individuals.
The differences in gut microbiome composition were confirmed in a larger independent cohort.
Certain gut microbes showed varying abundance in relation to amyloid status and apolipoprotein E (APOE) ε4 status.
Differentially abundant gut microbiome features are associated with cerebrospinal fluid biomarkers linked to AD and related pathologies.

Simplified

BACKGROUND: The gut microbiome is a potentially modifiable risk factor for Alzheimer's disease (AD); however, understanding of its composition and function regarding AD pathology is limited.

METHODS: Shallow-shotgun metagenomics was used to analyze the fecal microbiome of participants in the Wisconsin Microbiome in Alzheimer's Risk Study, leveraging clinical data and cerebrospinal fluid () biomarkers. and ordinary least squares regression analyses were performed to find differentially abundant gut microbiome features and their associations with CSF biomarkers of AD and related pathologies.

RESULTS: Gut microbiome composition and function differed between individuals with and without AD dementia. The compositional difference was replicated in an independent cohort. Differentially abundant gut microbiome features were associated with CSF biomarkers of AD and related pathologies.

DISCUSSION: These findings enhance our understanding of alterations in gut microbial composition and function in AD, and suggest that gut microbes and their pathways are linked to AD pathology.

HIGHLIGHTS: Gut microbiome composition and function differ between people with Alzheimer's disease (AD) dementia and cognitively unimpaired (CU) individuals. Co-occurring gut microbes show differential abundance across AD-related groups (AD vs CU, amyloid status+ vs amyloid status-, and apolipoprotein E (APOE) ε4 status+ vs APOE ε4 status-). Gut microbiome composition also differs between people with AD dementia and CU individuals in a larger validation cohort. Differentially abundant gut microbiome composition and function between AD and CU groups are correlated with cerebrospinal fluid biomarkers for AD and related pathologies.

Key numbers

232

Participants in study

Total number of participants recruited for microbiome analysis.

448

Independent cohort size for validation

Number of participants in the independent cohort for validation.

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Gut bacteria types and functions linked to Alzheimer's disease changes

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