Data and code files for paper "Ageing Gut-Brain Interactions: Proinflammatory gut bacteria are elevated in fecal samples from individuals living with Alzheimer’s dementia"

Alzheimer’s disease (AD) is the most common form of global dementia, characterized by an irreversible decline in cognitive function. The pathogenesis of several neurodegenerative disorders has been linked to dysbiosis of the gut microbiota through the gut-brain axis. We set out to establish by case-control study methodology whether there were any differences in the composition and/or function of the gut microbiota between older adults resident in care homes with or without an AD diagnosis.Based on the results of 16S rRNA gene profiling we established that AD sufferers had increased levels of <i>Escherichia/Shigella</i> and <i>Clostridium_sensu_stricto_1</i>, and decreased levels of <i>Bacteroides, Faecalibacterium, Blautia</i> and <i>Roseburia</i> species. The increased levels of potentially pro-inflammatory bacteria were consistent with slightly higher concentrations of calprotectin, a biomarker of gut inflammation. Levels of most microbial metabolites measured were similar across groups, although participants with AD had significantly increased proportions of the branched chain fatty acid, iso-butyrate and a decreased proportion of the specific short-chain fatty acid butyrate. Taken together these results show that participants with Alzheimer’s disease have several key differences within their gut microbiota profile, in contrast to care-home residents with no Alzheimer’s disease. The dysbiotic microbiome included both compositional and functional changes linked to poorer health and gut inflammation.