Ketamine is often thought of as an illicit party drug—something people take for a momentary high. But it wasn't designed to be a mind-altering drug. Originally, ketamine was developed as anesthetic to relieve temporary pain. And now it seems the drug can provide solace not just from physical distress. At the NIH, Dr. Carlos Zarate is investigating how ketamine can rapidly reduce depressive symptoms in people with treatment-resistant depression or bipolar depression, for whom other options have not helped.