IL6 and major depressive disorder: Previous studies have reported ECT-related changes in a few selected proteins, which include conflicting findings on brain-derived neurotrophic factor (9,14, 15, 16); acutely increased but long-term decreased levels of interleukin 6 (IL-6) and tumor necrosis factor α (TNF-α), suggesting a normalization of depression-related microglial activation (17); and unaltered levels of S100B and neuron-specific enolase, suggesting absence of significant neuronal damage (18, 19, 20).