Topiramate augmentation in treatment‐resistant obsessive–compulsive disorder: a retrospective, open‐label case series

Serotonin reuptake inhibitors (SRIs) are considered first-line treatments for obsessive-compulsive disorder (OCD). Many patients achieve some response but remain symptomatic despite an adequate SRI trial. Recent neuroimaging data found abnormally high glutamatergic concentrations in children with OCD. Following selective serotonin reuptake inhibitor (SSRI) treatment, a decrease in OCD symptom severity was associated with a decrease in caudate glutamatergic concentrations. We initiated an investigation of adjunctive topiramate (an anticonvulsant agent with glutamatergic properties) in the treatment of patients with OCD who were partially or nonresponsive to SRI treatment. Sixteen consecutive outpatients with OCD (mean age = 41.1 years; range = 21-58 years), who were partial or nonresponders to SRI monotherapy or SRI combination therapy (antipsychotic, other antidepressant, or benzodiazepines), and had topiramate added over a minimum of 14 weeks, were reviewed. Baseline and endpoint Clinical Global Impression-Severity (CGI-S) and CGI-Improvement (CGI-I) were evaluated retrospectively. Eleven of 16 patients were responders (68.8%) with a CGI-I score of much improved or very much improved. The mean dose of topiramate was 253.1 +/- 93.9 mg/day. The mean time to response was 9.2 +/- 4.5 weeks. CGI-S scores decreased significantly from initiation of topiramate until 26 weeks, from 6.1 +/- 0.9 to 4.5 +/- 1.3 (P < .001). This case series suggests some preliminary evidence that the addition of topiramate may be useful in treatment-resistant OCD.