BDNF has received increasing attention as a therapeutic target for depression because BDNF levels were reduced in mood disorders and preclinical depression models [33, 56], chronic treatment with anti-depressants increased brain BDNF gene expression and signaling [9], treatment with anti-depressants increased BDNF in serum in patients [53], and an infusion of BDNF into the midbrain [55] or hippocampus [54] produced anti-depressant-like effects in animal models of depression. The gene discussed is BDNF; the disease is major depressive disorder.