CCK and major depressive disorder: Additionally, we identified 12 genes from the most ranked down- and upregulated DEGs associated with depression, such as GABRD, IL6, NOTCH1, EGFR, ERBB2, TLR4, STAT3, GRIK1, GRIK2, CACNA1G, CCK and CRHR1 and six genes from the hub gene list of the co-expression analysis, including BCL2, CHDH, GABRD, NRGN, SERPINF1 and CCK.