Serotonin Transporter Imaging with [¹²³I]β-CIT SPECT before and after One Year of Citalopram Treatment of Obsessive-Compulsive Disorder

Abstract

Background: Two thirds of patients with obsessive-compulsive disorder (OCD) respond to treatment with selective serotonin reuptake inhibitors (SSRIs). The neurobiological mechanisms of SSRI action and failure to respond to SSRI treatment remain to be elucidated. Objectives: The aim of this pilot study was to quantify changes in the availability of serotonin transporter (SERT) in the course of SSRI treatment and to relate these changes to improvements of clinical symptoms. Methods: Ten patients with OCD were investigated at baseline and 5 of them after 1 year of SSRI treatment with citalopram 60 mg per day using brain single photon emission computed tomography and [¹²³I]β-CIT. Specific-to-nondisplaceable [¹²³I]β-CIT binding ratios (V₃″) were calculated in SERT-rich brainstem, midbrain and thalamus using a magnetic resonance imaging-based region of interest (ROI) analysis. Symptom severity was evaluated with the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS). Results: V₃″ differed significantly between pretreatment and follow-up scans in all three brain regions, thalamus, midbrain as well as in brainstem. In thalamic ROI, differ ences in SERT availability and Y-BOCS ratings correlated. In midbrain, a trend toward a significant association was found. In brainstem, no relationship was revealed. Conclusions: Higher occupancy of SERT by citalopram seems to be associated with better clinical response after 1 year of SSRI treatment of patients with OCD.

Changes in Thalamus–Hypothalamus Serotonin Transporter Availability during Clomipramine Administration in Patients with Obsessive–Compulsive Disorder

“…This result is inconsistent with a pilot b-CIT study involving five OCD patients by Stengler-Wenzke et al (2006) who found a positive association between individual SERT occupancy by citalopram and clinical response after 1 year of treatment. However, we cannot compare the results of this pilot study with our findings as: (1) in the study of Stengler-Wenzke it was not possible to differentiate the effects of SSRI treatment and complementary interventions because all five patients attended an OCD outpatient program including elements of cognitive-behavior therapy and psychoeducation; and (2) statistical calculations based on only five patients are unreliable.…”

“…The SPECT acquisition time of 4 h post injection used in the present study and in the studies by van der Wee et al (2004) and Zitterl et al (2007) differed from several previous studies, where imaging was performed at 20 or 24 h post injection (Pogarell et al, 2003;Stengler-Wenzke et al, 2004, 2006Hesse et al, 2005). Kinetic studies of b-CIT uptake in SERT-rich brain areas showed a peak in tracer uptake in the thalamus-hypothalamus at 4 h post injection, followed by stable uptake up to 10 h, and a slow decrease up to 24 h post injection.…”

“…The authors are not aware of any studies examining SERT availability in treated OCD patients with the exception of a pilot study of Stengler-Wenzke et al (2006), who treated five OCD patients with citalopram.…”

“…The only study in which SERT binding has been investigated in obsessive-compulsive disorder (OCD) patients before and after treatment is a small pilot study by Stengler-Wenzke et al (2006), who treated five OCD patients with citalopram. In the study at hand, we measured transporter availability in the thalamus-hypothalamus with [ 123 I] b-CIT single photon emission computed tomography (SPECT) in 24 patients with DSM-IV OCD.…”

The Treatment of Obsessive-Compulsive Disorder and the Approaches to Treatment Resistance

“…Its efficacy and safety as first line treatment or in case of treatment-resistance for OCD has been proved in various single and double blind trials (Marazziti et al, 2001;Pallanti et al, 1999;Pidrman et al, 1997;Stengler-Wenzke et al, 2006). Montgomery et al (Montgomery et al, 2001) confronted in a double-blind trial the efficacy of different citalopram dosages (20,40, 60 mg/die) and placebo; the Authors reported the effectiveness of all of the three dosages, with a slight advantage for the higher one, particularly in terms of rapidity of response.…”