TNF and major depressive disorder: Additionally, a previous meta-analysis confirmed elevated TNF-α concentrations in DN MDD patients relative to controls (SMD 1.04, 95% CI: 0.69–1.39, z = 5.84, p < 0.001) [19] and a meta-analysis on FE DN individuals also showed similar results (g = 1.21; 95% CI, 0.57 to 1.85; p < 0.001; I2 = 89%) [20].