Chronically activated microglia, increased cell density and hyper-ramified morphology (Dubbelaar et al., 2018), and the enhanced release of pro-inflammatory cytokines, e.g., TNF-α, IL-1β, and IL-18, are observed in response to stress, major depression, or AD, leading to disease progression and brain damage (Pickering and O’Connor, 2007). This evidence concerns the gene TNF and major depressive disorder.