Dopamine D1 receptor binding in obsessive-compulsive disorder

Abstract

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Objectives: Obsessive-compulsive disorder (OCD) has been suggested to be a neurobiological disorder arising from abnormalities in the serotonergic system. Despite the therapeutic efficacy of serotonin uptake inhibitors, evidence from neurobiological studies does not provide consistent evidence for serotonergic abnormality. Converging lines of evidence suggest a role for dopamine in OCD. This study investigates the binding potential change of [11C]-SCH23390 to dopamine D1 receptors in patients with OCD. Methods: Seven patients fulfilling the DSMIV criteria for OCD and seven age and gender matched (39 ± 14 years) volunteers underwent a single 60 minute dynamic positron emission tomography (PET) scan with [11C]SCH23390 (630 ± 100 MBq) with a Specific Activity of 820 ± 400 Ci/mM. PET scans were co-registered to individual MRI and regions of interest compared. From the individuals MRI, a cerebellar grey-tissue was defined as the reference region. Logan graphical analyses was performed and Distribution Volume Ratios (DVR’s) defined for caudate, putamen, anterior cingulate, orbito-frontal-cortex and thalamus. Results: Significant reductions in D1 binding potential were found in the caudate nuclei (p = 0.026) and putamen (p = 0.037) of patients in comparison to controls. A cortical grey matter region distinct from the cerebellar reference region was selected and revealed no significant difference (p = 0.212). Conclusions: This study is the first demonstration of a dopamine D1 abnormality in OCD. The findings implicate dopamine in the neurobiology of OCD and may help explain neuropsychological and neuroimaging findings associated with the disorder.