Gut & MicrobiomeGut Microbiome Diversity Fails as Alzheimer's Biomarker in Major Meta-Analysis
A new systematic review and meta-analysis pooling data from 23 observational studies found that standard measures of gut microbial diversity — such as Shannon, Chao1, and ACE indices — do not significantly differ between people with Alzheimer's disease or mild cognitive impairment and cognitively normal older adults. While the gut-brain connection in Alzheimer's remains biologically plausible, this analysis covering nearly 2,250 participants suggests that simple diversity scores are not reliable biomarkers for detecting or staging cognitive decline. However, deeper analyses of microbial community structure and specific bacterial taxa showed more consistent disruption in Alzheimer's patients, pointing researchers toward more sophisticated, function-oriented microbiome profiling as the next step in this field.
