Abstract Details

Title The Role of the Microbiome Across Neurological and Neurodegenerative Disorders: A Quantitative Systematic Review

Topic General Neurology

Presentation(s) P8 - Poster Session 8 (11:45 AM-12:45 PM)

Poster/Presentation
Number 7-003

Objective

Evaluate clinical associations between microbiome features and neurological disorders and test whether directional taxonomic shifts are consistent within and across diseases, emphasizing Alzheimer’s disease (AD) and Parkinson’s disease (PD).

Background The human microbiome influences metabolism, immunity, and brain health. Dysbiosis has been linked to neurologic conditions, but the consistency of clinical associations and taxon-level enrichment or depletion across diseases remains unclear.

Design/Methods We conducted an umbrella review of 63 studies (past 10 years; PRISMA). From each study we extracted specimen site, sequencing modality (16S/shotgun), design, diversity metrics, reported taxa and their enrichment or depletion relative to control, and clinical scales. Clinical-association was coded (Yes/No/Not Reported) if a statistically significant association between a microbiome measure and clinical phenotype was described. We performed a vote-count synthesis: for each (taxon, disease) we tallied enrichment and depletion, computed net effect and support (total studies), and compared bins with Fisher’s exact tests. Prespecified bins captured canonical short-chain fatty acid (SCFA) producers.

Results Clinical associations were reported in 40/44 evaluable (90.9%) studies. Across disorders, SCFA-producing taxa (e.g., Faecalibacterium, Roseburia, Blautia, Agathobacter, Eubacterium, Butyricicoccus, Ruminococcus) were significantly more often depleted than enriched (2×2 table [[39 pos, 24 neg] vs [11 pos, 52 neg]]; OR = 7.68, p = 5.3×10?7). Disease-specific patterns mirrored this signature: PD: recurrent depletion of SCFA-linked taxa (Faecalibacterium, Roseburia, Blautia) with enrichment of other genera (e.g., Akkermansia, Desulfovibrio, Escherichia). AD: frequent depletion of SCFA taxa (Faecalibacterium, Eubacterium, Roseburia), with variable enrichment of Bacteroides, Akkermansia, and Prevotella. Signals spanned multiple sites and methods, with heterogeneity and stage-specific effects (e.g., preclinical AD).

Conclusions A reproducible cross-disease signature of SCFA-producer depletion accompanies neurological disorders and co-varies with clinical scales. This evidence synthesis clarifies within-disease consistency versus mixed findings—particularly in AD and PD—and supports the need for standardized, longitudinal, multi-omics studies to refine causality and enable robust diagnostic biomarkers.

Authors/Disclosures
Emily C. Song PRESENTER	Ms. Song has nothing to disclose.
Samuel Degregori	Dr. Degregori has nothing to disclose.
Harrison Gu	Mr. Gu has nothing to disclose.
Isabella Huang	Miss Huang has nothing to disclose.
David Kobobel	Mr. Kobobel has nothing to disclose.
Rob Knight, PhD	Prof. Knight has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Cybele Microniome, Inc. . Prof. Knight has received personal compensation in the range of $0-$499 for serving as a Consultant for DayTwo, Ltd.. Prof. Knight has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for BiomeSense, Inc. . Prof. Knight has received personal compensation in the range of $0-$499 for serving on a Scientific Advisory or Data Safety Monitoring board for GenCirq, Inc. . Prof. Knight has stock in Biota, Inc.. Prof. Knight has stock in Micronoma.

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