IFNG and major depressive disorder: Animal and microglia studies have indicated that depression is associated with neuroinflammation [9,10] including sterile inflammation, glial cell activation, and elevated levels of interleukin-6 (IL-6), IL-10, IL-1β, and tumor necrosis factor-alpha (TNF-α) alongside reduced gamma interferon (IFN-γ) concentrations [11].