Alzheimer's Disease Microbiome Is Associated with Dysregulation of the Anti-Inflammatory P-Glycoprotein PathwayOriginal paper
Karen Pendergrass is a microbiome researcher specializing in microbiome-targeted interventions (MBTIs). She systematically analyzes scientific literature to identify microbial patterns, develop hypotheses, and validate interventions. As the founder of the Microbiome Signatures Database, she bridges microbiome research with clinical practice. In 2012, based on her own investigative research, she became the first documented case of FMT for Celiac Disease, four years before the first published case study.
Read MoreWhat was studied?
This prospective cohort study asked how the gut microbiome differs in Alzheimer's disease and whether it disrupts intestinal homeostasis. Researchers collected monthly stool samples and ran shotgun metagenomic sequencing. They used machine learning (random forest) to find taxa that separate Alzheimer's from other groups. They also tested whether stool could alter P-glycoprotein, a mediator of gut anti-inflammatory balance. Stool supernatants were applied to T84 intestinal epithelial cells to measure P-glycoprotein and MRP2 protein expression.
Who was studied?
The cohort was 108 nursing home elders in central Massachusetts, all aged 65 or older, followed up to 5 months. Of these, 51 had no dementia, 24 had Alzheimer's disease, and 33 had other dementia types. Across groups, 300 longitudinal stool samples were collected, one per elder per month. Elders exposed to antimicrobials, hospitalization, or medication changes were excluded. Elders with dementia, including the Alzheimer's group, had higher malnutrition and frailty scores and more often took atypical antipsychotics than elders without dementia.
What were the most important findings?
Stool from Alzheimer's elders induced significantly lower functional P-glycoprotein expression than stool from other groups (p = 0.017). Lower P-glycoprotein signals a more proinflammatory gut epithelial state. Alzheimer's microbiomes had lower proportions of butyrate-producing species and fewer butyrate biosynthesis genes across four pathways. Proinflammatory and neurologically linked taxa were enriched in Alzheimer's elders. Frailty and malnutrition, plus specific taxa, accurately classified Alzheimer's versus no dementia in random forest models.
What are the greatest implications of this study?
The results suggest the Alzheimer's gut microbiome may promote intestinal inflammation by lowering P-glycoprotein, a possible link in the gut-brain axis. This moves association studies toward a plausible mechanism. Butyrate-producing bacteria emerge as a candidate for study and future intervention in dementia. This is observational work in frail elders, so causation is not established. Confounders like malnutrition and medications were modeled but cannot be fully excluded.