Objective   To identify the differences in the composition of gut microbiota of patients with post-stroke cognitive impairment (PSCI) in comparison with the normal cognition healthy controls (HC), and to study the potential association between gut microbiota and cognition function.

  Methods   A total of 24 patients were recruited for the PSCI group, which was matched with 23 healthy subjects with no history of cardiovascular disease recruited over the same period for the control group. Fecal samples were collected for both groups, and Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) were used to evaluate cognitive functions. The abundance, diversity and group difference of gut bacterial communities were determined with 16S rRNA gene sequencing, and the correlations between differences in bacterial species of the gut microbiota and cognitive function scores were examined with redundancy analysis (RDA)/canonical correspondence analysis (CCA).

  Results   There was no significant difference in the general data or the alpha diversity of gut microbiota between the two groups (P>0.05). Inter-group comparison of microbial species composition revealed differences at the phylum and species levels, mainly represented as reduction in the relative abundance of Firmicutes and Bacteroidetes, and the relative enrichment of Proteobacteria. The relative abundance ofIntestinibacter bartlettii, uncultured bacterium Tyzzerella_3, Lactobacillus gasseri, and Fusicatenibacter saccharivorans of phylum Firmicutes in the PSCI patients were significantly reduced in comparison to that of the HC (LDA score>2), and these bacteria were positively correlated with MMSE and MoCA scores. In addition, theRuminococcus gnavus and Faecalimonas umbilicata of phylum Firmicutes and unculturedbacteriumPrevotellaceae_NK3B31 group of phylum Bacteroidetes were significantly enriched in comparison with those of the HC (LDA score>2), and these bacteria were negatively correlated with MMSE and MoCA scores. There were also correlations among these bacteria.

  Conclusion   In this study, we observed compositional differences between the gut microbiota of PSCI patients and those of HC, and revealed that the differences were correlated, to some degree, to the cognitive functions, which will provide new perspectives for the clinical diagnosis and treatment of PSCI.