You do realize they already are investigating, right? Even looking into MS and parkinson. ALZHEIMER’S DISEASE (AD) and AD DEMENTIA Umbrella review (systematic reviews of SRs): https://www.nature.com/articles/s44400-025-00048-6

Systematic review + meta-analysis (basal microbiota; AD): https://alz-journals.onlinelibrary.wiley.com/doi/abs/10.1002... https://pmc.ncbi.nlm.nih.gov/articles/PMC11672027/

Replicated case-control + functional metagenomics (AD dementia): https://alz-journals.onlinelibrary.wiley.com/doi/full/10.100...

Large-cohort metagenomics (stage-specific / early pathology signals): https://pubmed.ncbi.nlm.nih.gov/40164697

Mendelian randomization (AD): https://pubmed.ncbi.nlm.nih.gov/38788075/ https://www.sciencedirect.com/science/article/pii/S227458072... https://pubmed.ncbi.nlm.nih.gov/40665707/ https://journals.sagepub.com/doi/10.1177/25424823261422629 https://www.medrxiv.org/content/10.1101/2025.08.20.25333769v...

Narrative / mechanisms (useful synthesis, not primary causal proof): https://www.sciencedirect.com/science/article/abs/pii/S15681...

MILD COGNITIVE IMPAIRMENT (MCI) / DEMENTIA (cognition-focused evidence) Systematic review (MCI or Alzheimer’s dementia; PRISMA, PROSPERO): https://www.mdpi.com/2035-8377/17/10/155 https://pubmed.ncbi.nlm.nih.gov/41149776/

Scoping review (MCI and AD gut microbiomes + interventions, through Feb 2023): https://pmc.ncbi.nlm.nih.gov/articles/PMC12825029/

Systematic review of microbiota-targeted interventions for cognition/dementia risk: https://www.sciencedirect.com/science/article/pii/S027153172...

RCT-focused systematic review/meta-analysis of probiotics for cognitive impairment risk/AD/MCI: https://pmc.ncbi.nlm.nih.gov/articles/PMC12645680/

FMT in dementia/MCI context (review of effects across neuro cohorts): https://www.sciencedirect.com/science/article/pii/S266635462...

MULTIPLE SCLEROSIS (MS) Microbiome signatures via global data integration / ML: https://pmc.ncbi.nlm.nih.gov/articles/PMC12383397/

Systematic review/meta-analysis of probiotics in MS (preclinical + clinical): https://journals.plos.org/plosone/article?id=10.1371/journal...

Systematic review + meta-analysis (antimicrobial exposure and MS risk; microbiome-disruption relevant): https://www.sciencedirect.com/science/article/abs/pii/S22110...

Mendelian randomization (gut microbiota causally linked to MS): https://pubmed.ncbi.nlm.nih.gov/39065244/ https://www.mdpi.com/2076-2607/12/7/1476

Broad MS gut dysbiosis and therapeutic modulation review: https://pmc.ncbi.nlm.nih.gov/articles/PMC12668904/

MS gut-brain-barrier and intestinal barrier review: https://www.frontiersin.org/journals/immunology/articles/10....

Example MS cohort biomarker/signature work: https://www.nature.com/articles/s41598-024-64369-x https://www.nature.com/articles/s41598-025-19998-1

PARKINSON’S DISEASE (PD) Multi-cohort metagenomic meta-analysis (Nat Commun, 2025): https://www.nature.com/articles/s41467-025-56829-3 https://pubmed.ncbi.nlm.nih.gov/40335465/

Large metagenomics cohort (Nat Commun, 2022): https://www.nature.com/articles/s41467-022-34667-x

Integrated multi-cohort gut metagenome (Movement Disorders, 2023): https://pubmed.ncbi.nlm.nih.gov/36691982/ https://movementdisorders.onlinelibrary.wiley.com/doi/10.100...

Metagenomic analysis (Movement Disorders, 2024): https://pubmed.ncbi.nlm.nih.gov/39192744/

PD causal-inference and MR discussion (review-type synthesis): https://pmc.ncbi.nlm.nih.gov/articles/PMC12512240/

MR study example (PD gut microbiota): https://journals.lww.com/md-journal/fulltext/2025/10310/caus...