Researchers from Cardiff University and Imperial College London have identified specific gut bacteria and chemical biomarkers that distinguish adults with mild cognitive impairment from healthy individuals and predict the speed of cognitive decline over one year. Published in MedComm on October 19, 2026, the machine-learning study on cohabitating couples revealed elevated Izemoplasmatales spp. and proline in impaired adults. Scientists emphasize larger, diverse trials are needed to confirm the findings.
Fecal biomarkers in mild cognitive impairment
- ▪A study published in MedComm found that adults with mild cognitive impairment showed decreased levels of Ruminococcus spp. and Lachnospira spp. bacteria alongside lower levels of fumaric acid.
- ▪Researchers from Cardiff University and Imperial College London found that older adults with mild cognitive impairment displayed significantly elevated levels of Izemoplasmatales spp. bacteria and the chemical proline in fecal samples.
Biomarkers predicting faster cognitive decline
- ▪A Cardiff University and Imperial College London study found that individuals with mild cognitive impairment who had higher initial levels of Bilophila spp. bacteria and the chemicals arginine, aspartic acid, and hypoxanthine experienced faster cognitive decline over one year.
- ▪Researchers found that lower initial levels of Coprococcus spp. bacteria in individuals with mild cognitive impairment were associated with faster memory and thinking skills decline over a one-year follow-up period.
Machine learning and diagnostic accuracy
- ▪Study co-author Dr. You Zhou stated that combining gut bacteria and digestive chemicals distinguished individuals with mild cognitive impairment from healthy people with high accuracy.
- ▪The study utilized machine learning algorithms to analyze fecal sample biomarkers to diagnose mild cognitive impairment and predict condition progression speed.
- ▪In an independent validation cohort from a previous study, bacterial gut markers successfully distinguished people with mild cognitive impairment from healthy individuals.
Expert perspectives on the gut-brain link
- ▪Professor Julian Marchesi of Imperial College London stated that gut bacteria and digestive chemicals are increasingly recognized as an important link between the gut and the brain.
- ▪Professor Paul Morgan of Cardiff University stated that the gut could offer a window into brain changes occurring during the earliest stages of cognitive decline.
Directions for future research
- ▪Authors of the MedComm study indicated that future research needs to examine the influences of diet, lifestyle, ethnicity, environment, and genetic risk on gut microbial markers.
- ▪Researchers stated that future clinical studies must evaluate gut microbiome markers across larger and more diverse demographic cohorts.
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