Clinical utility of repeated intravenous ketamine treatment for resistant obsessive-compulsive disorder

Glutamate modulators are used to treat OCD resistant to serotonin reuptake inhibitors (SRIs). Ketamine has shown some promise in treating OCD. Data on the use of ketamine in SRI-resistant OCD is limited, with no studies on the role of multiple ketamine infusions in this disorder. We report our experience of treating SRI- resistant OCD with multiple ketamine infusions. We reviewed the clinical charts of 14 adult inpatients with a diagnosis of SRI-resistant OCD and treated them with repeated ketamine infusions [mean (SD) = 5.4 (2.5)]. There was a significant reduction in the Yale-Brown Obsessive-Compulsive Scale (YBOCS) total score following intravenous ketamine infusions. One patient showed a dramatic response (a drop in the YBOCS to '0') and two patients showed a partial response (25-35 % reduction in the YBOCS). Eleven patients showed no clinical improvement. Ketamine may, therefore, be somewhat effective in a subset of OCD patients who are resistant to SRIs. Our findings suggest the need to examine the efficacy of ketamine in controlled studies with larger samples. It may be possible to identify predictors of response to ketamine in larger studies.