Introduction
Obsessive-compulsive disorder (OCD) is characterized by recurrent, intrusive thoughts or stereotyped behaviour that interfere with daily living. Advanced structural and functional imaging tools have provided us with valuable information about the neuroanatomical pathophysiology in OCD patients. The objective of this study was to explore associations between regions within the orbitofrontal, dorsolateral, motor and limbic loop before treatment and after successful treatment with a selective serotonin reuptake inhibitor (SSRI). Methods. Twenty outpatients with OCD underwent two PET-FDG scans with an interval of 3–6 months. Regional cerebral glucose metabolism was quantitated using the autoradiographic.
Method
The PET scans were preprocessed using SPM 99 and a region of interest (ROI)-based data extraction was done using in-house developed Matlab based software, 14 ROIs considered of relevance for OCD were included in the analysis. The 14 ROI's were segmented into four different cortico-striatal-thalamo-cortical-circuits. Regression analyses were done between ROI's in OCD patients before and after SSRI treatment. The Generalized Estimating Equation approach with an interaction term was applied to examine the associations between ROI's in OCD patients before and after SSRI treatment.
Results
A significant negative association between the left caudate/ventral striatum and the left anterior cingulate was identified in OCD patients post treatment; however, there were no significant association before SSRI treatment. A negative association was found between right supplementary motor area and right putamen; and the association became weaker after treatment.
Conclusions
Associations in glucose metabolism between brain circuits in patients with OCD are significantly altered upon successful pharmacological treatment. This finding may contribute to our understanding of OCD pathophysiology.