In a meta-analysis study of 827 patients suffering with major depressive disorder (MDD), the pooled effect estimate using bias-corrected standardized mean difference indicates that SSRI treatment decreases serum levels of pro-inflammatory cytokines, IL-6, TNFα, and IL-1β, and anti-inflammatory cytokine IL-10 (194, 197–199). This evidence concerns the gene TNF and major depressive disorder.