Adult hippocampal neurogenesis and psychiatric disorders. Shown at the top is a schematic illustration of stages showing specific stages of adult hippocampal neurogenesis. Shown at the bottom is a summary of effect of three different classes of psychiatric disorders on hippocampal volume and adult hippocampal neurogenesis, including depression, schizophrenia or drug addiction. Note that multiple developmental stages during adult neurogenesis are shown to be affected. RGL, Radial glia-like cells; ECT, electroconvulsive therapy; KO, knockout; KD, knockdown; MDMA, 3,4-methylenedioxymethamphetamine.