D-cycloserine augmented exposure therapy for obsessive-compulsive disorder

Background: D-cycloserine (DCS), a glutamatergic partial N-methyl-D-aspartate (NMDA) agonist, can facilitate extinction learning related to cued fear in animals and humans. We predicted that DCS would accelerate obsession-related distress reduction in patients with obsessive-compulsive disorder (OCD) undergoing extinction-based exposure therapy. Methods: We administered DCS (1125 mg) or placebo in a double-blind fashion to individuals with OCD approximately 2 hours before each exposure session. Results: D-cycloserine decreased both the number of exposure sessions required to achieve clinical milestones and the rate of therapy dropout. After four exposure sessions, patients in the DCS group reported significantly greater decreases in obsession-related distress compared with the placebo group; however, after additional sessions, the placebo group tended to catch up. Conclusions: D-cycloserine augmentation has the potential to increase the efficiency, palatability, and overall effectiveness of standard exposure therapy for OCD.