Physiological and Cognitive Biomarkers for Ketamine's Antidepressant Effects

Anxious depression is a particularly difficult-to-treat subtype of depression. Patients with anxious depression do not respond as well to currently available antidepressant medications. Nevertheless, in previous studies, low dose IV ketamine, which rapidly decreases symptoms of depression within hours in many patients with "treatment-resistant" depression, has been associated with superior efficacy in those individuals with anxious compared with non-anxious depression. In order to understand this unique effect more fully, the current protocol is aimed at further delineating biomarkers of ketamine's effects among individuals with treatment-resistant anxious depression compared to those with nonanxious depression.