Dysregulation in IEGs has been implicated in many neurological diseases, including increased circulating Egr1 in schizophrenia [77, 78], increased Arc in the amygdala in major depressive disorder [79, 80], and increased cFos and cJun in the hippocampus and amygdala in AD [81–83]. The gene discussed is ARC; the disease is major depressive disorder.