Many patients with Obsessive Compulsive Disorder (OCD) fail to respond to specific serotonin reuptake inhibitor (SSRI) medications. Glutaminergic dysfunction has been shown to be related to the pathophysiology of OCD. Topiramate is a novel anti-epileptic drug that inhibits glutaminergic action. The aim of this study is to survey the effects of topiramate on obsessions and compulsions of patients with OCD.

This trial has been designed as an 8-week randomized, placebo-controlled, double-blind study. Eighty four patients suffering from OCD were randomly allocated in to one of the treatment group: fluoxetine plus topiramate or fluoxetine plus placebo. Efficacy measures comprised assessment of obsessions and compulsions and global functioning.

Both groups demonstrated significant improvement in their clinical condition (P< .000) but the group taking topiramate adjunctive compared to the other group had more decrease in Yale-Brown Obsessive Compulsive Scale (P< .001) and better Clinical Global Improvement (P< .002).

Our study indicates that topiramate can enhance the effect of SSRIs in treatment of OCD patients and can be considered as an appropriate adjunctive agent. However, it should be noted that our study is preliminary and larger double blind studies are needed to confirm these results.