Many hypotheses about the exact mechanisms underlying how neuropathology develops in COVID-19 patients have been formulated and investigated in patient cohorts and in vivo studies, including the involvement of IL-6 and different isoforms of cytokines, the complement pathway and microthrombosis, neuronal loss and degeneration, and increases in IL-1β and IL-6 levels within the hippocampus, leading to decreased neurogenesis and memory impairment [235]. This evidence concerns the gene IL6 and memory impairment.