Diencephalic serotonin transporter availability predicts both transporter occupancy and treatment response to sertraline in obsessive-compulsive checkers.

Background: To our knowledge, no studies have investigated the predictive value of central serotonin transporter (SERT) availability for treatment response to serotonin reuptake inhibitors (SSRIs) in patients with obsessive-compulsive disorder (OCD). This study used brain imaging to examine the relationship between pretreatment SERT availability and transporter occupancy as well as treatment response by sertraline in patients displaying prominent behavioral checking compulsions (OC checkers).
Methods: Single photon emission computed tomography (SPECT) was used to measure thalamic-hypothalamic SERT availability with [(123)I]-2beta-carbomethoxy-3beta-(4-iodophenyl)-tropane in 28 nondepressed OC checkers at baseline and after 14 weeks of treatment with sertraline (175 mg daily). SERT availability was correlated with OC severity and treatment response as assessed with the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS). Associations between individual transporter occupancies and clinical parameters were investigated.
Results: 1) Correlation analyses between thalamic-hypothalamic SERT availability and OC severity showed significant negative associations at baseline and after treatment with sertraline. 2) Pretreatment SERT availability correlated significantly with both transporter occupancy and treatment response; in addition, a positive association was found between transporter occupancy and treatment response directly. 3) Using multivariate statistical models, the data demonstrated that higher pretreatment SERT availability significantly predicted higher occupancy rates as well as better treatment response 14 weeks later.
Conclusions: Higher pretreatment thalamic-hypothalamic SERT availability may predict both higher occupancy rates and better treatment response to sertraline. The data suggest a strong connection between transporter occupancy and treatment response.