SUMMARY
# Microbiome-Gut-Brain Axis in Alzheimer's Disease — mechanism and intervention
## Background and Rationale
The microbiome-gut-brain axis represents a bidirectional communication network between the gastrointestinal tract and central nervous system, mediated by neural, hormonal, and immunological pathways. Emerging evidence suggests that gut microbiome dysbiosis contributes to Alzheimer's disease (AD) pathogenesis through multiple mechanisms, including increased intestinal permeability, systemic
METHODOLOGY NOTES
Phase 1 (Months 1-6): Recruit 300 participants meeting inclusion criteria through memory clinics and community screening. Collect baseline samples including fecal specimens for microbiome analysis (16S rRNA sequencing, shotgun metagenomics), blood samples for LPS, zonulin, inflammatory cytokines (IL-6, TNF-α, CRP), and AD biomarkers (Aβ42, tau, p-tau). Perform comprehensive cognitive assessment using ADAS-Cog, MMSE, and MoCA scales. Conduct structural MRI and PET imaging for amyloid and tau burden. Phase 2 (Months 7-12): Randomize subset of 150 participants to interventional arm receiving either multi-strain probiotic containing Lactobacillus helveticus R0052, Bifidobacterium longum R0175, and Lactobacillus rhamnosus R0011 (10^9 CFU daily) or matched placebo. Continue monthly monitoring of all participants with abbreviated assessments. Phase 3 (Months 13-18): Mid-study comprehensive reassessment replicating baseline measures. Analyze interim microbiome changes and LPS levels to assess