Objective: This study examined whether d-cycloserine, a partial agonist at the N-methyl-D-aspartate (NMDA) glutamatergic receptor, enhances the efficacy of behavior therapy for obsessive-compulsive disorder (OCD).
Method: A randomized, double-blind, placebo-controlled trial investigating D-cycloserine versus placebo augmentation of behavior therapy was conducted in 23 OCD patients. Patients first underwent a diagnostic interview and pretreatment evaluation, followed by a psychoeducational/treatment planning session. Then they received 10 behavior therapy sessions. Treatment sessions were conducted twice per week. One hour before each of the behavior therapy sessions, the participants received either D-cycloserine, 100 mg, or a placebo.
Results: Relative to the placebo group, the D-cycloserine group's OCD symptoms were significantly more improved at mid-treatment, and the D-cycloserine group's depressive symptoms were significantly more improved at posttreatment.
Conclusions: These data provide support for the use of D-cycloserine as an augmentation of behavior therapy for OCD and extend findings in animals and other human disorders suggesting that behavior therapy acts by way of long-term potentiation of glutamatergic pathways and that the effects of behavior therapy are potentiated by an NMDA agonist.