Previous studies on the variation of IL-8 in mood disorders have been inconsistent, possibly because of the large variations in IL-8 concentrations in plasma.[14] In agreement with our results, 1 study has found no significant differences in IL-8 between MDD patients and healthy individuals.[14] Another study has found lower levels of IL-8 in patients with MDD.[29] Several studies have suggested that imbalanced IL-8 levels, whether elevated or reduced, may be due to whether the patient has obvious anxiety symptoms.[29,30]. This evidence concerns the gene CXCL8 and mood disorder.