Fig. 1

POCD patients exhibit a shift in the preoperative gut microbiota composition. Comparison of BMI (A) and preoperative MMSE score (B) between POCD patients (n = 24) and control patients (n = 24). C Venn diagram of ASVs. D The α-diversity indices of the ACE, Chao, Shannon and Simpson indices. E The β-diversity analysis of the PCoA plot based on weighted UniFrac distances. Changes in the relative abundances of the main bacterial communities at the phylum (F) and genus (G) levels. The relative abundances of bacterial communities with significant differences at the phylum (H) and genus (I) levels. J Cladogram of LEfSe results comparing bacterial communities from the phylum to genus level. K ROC curves of the two predictive models with or without data on the preoperative gut microbiota. L KEGG pathway functional gene difference analysis. Data are expressed as mean ± SEM. *P < 0.05, **P < 0.01, ***P < 0.001