TNF and major depressive disorder: TNF-α and IL-1β are pro-inflammatory cytokines that affect neuronal function by regulating oxidative stress, apoptosis, and metabolism, and impairing neuronal branching processes (Wang et al., 2019) There is evidence demonstrating that TNF-α plays a critical role in the cognitive decline and the progression of depression and anxiety, while both IL-1β and TNF-α are elevated in patients with depression.