TNF and major depressive disorder: Further, within the MDD/SA group, we investigated the association between IL-6 and TNF-α on one hand (as a predictor) and BDI and SSI on the other (as a response), and found no significant associations longitudinally between BDI scores and the two cytokines [BDI and IL-6: b = 3.25, 95% CI = (−0.89, 7.26), p = 0.1234, or BDI and TNF-α: b = 8.07, 95% CI = (−5.07, 20.94), p = 0.2033].