Integrated Microbiome and Metabolomic Profiling to Identify Potential Biomarkers of Major Depressive Disorder

in MDD patients. Integrated correlation analysis revealed a functional "gut-lipid axis", where these taxa were strongly associated with alterations in host acylcarnitine and fatty acid metabolism. Notably, diagnostic evaluation demonstrated that the plasma metabolic profile yielded superior predictive accuracy (AUC = 0.862) compared to the gut microbiota (AUC = 0.654). Our findings suggest that while the gut microbiome provides mechanistic insights into lipid dysregulation, the circulating metabolome serves as a more robust, proximal diagnostic readout for MDD.