Obsessive compulsive disorder networks: positron emission tomography and neuropsychology provide new insights.

BACKGROUND: Deep brain stimulation has shed new light on the central role of the prefrontal cortex (PFC) in obsessive compulsive disorder (OCD). We explored this structure from a functional perspective, synchronizing neuroimaging and cognitive measures. METHODS AND FINDINGS: This case-control cross-sectional study compared 15 OCD patients without comorbidities and not currently on serotonin reuptake inhibitors or cognitive behavioural therapy with 15 healthy controls (matched for age, sex and education level) on resting-state (18)FDG-PET scans and a neuropsychological battery assessing executive functions. We looked for correlations between metabolic modifications and impaired neuropsychological scores. Modifications in glucose metabolism were found in frontal regions (orbitofrontal cortex and dorsolateral cortices), the cingulate gyrus, insula and parietal gyrus. Neuropsychological differences between patients and controls, which were subtle, were correlated with the metabolism of the prefrontal, parietal, and temporal cortices. CONCLUSION: As expected, we confirmed previous reports of a PFC dysfunction in OCD patients, and established a correlation with cognitive deficits. Other regions outside the prefrontal cortex, including the dorsoparietal cortex and the insula, also appeared to be implicated in the pathophysiology of OCD, providing fresh insights on the complexity of OCD syndromes.

Decrease of prefrontal metabolism after subthalamic stimulation in obsessive-compulsive disorder: a positron emission tomography study.

BACKGROUND: High-frequency bilateral subthalamic nucleus (STN) deep brain stimulation (DBS) is a promising treatment in refractory obsessive-compulsive disorder (OCD). METHOD: Using the crossover, randomized, and double-blind procedure adopted by the STOC study, 10 patients treated with high-frequency bilateral STN DBS underwent am 18-fluorodeoxyglucose positron emission tomography (PET) investigation to highlight the neural substratum of this therapeutic approach. RESULTS: The median Yale-Brown Obsessive Compulsive Scale (Y-BOCS) scores for all 10 patients were 31 (minimum = 18, maximum = 36) with "Off-Stimulation" status and 19 (minimum = 0, maximum = 30) with "On-Stimulation" status (p = .05). The OCD patients in Off-Stimulation status showed a hypermetabolism in the right frontal middle and superior gyri, right parietal lobe, postcentral gyrus, and bilateral putamen compared with healthy control subjects. A significant decrease in cerebral metabolism was observed in the left cingulate gyrus and the left frontal medial gyrus in On-Stimulation conditions compared with Off-Stimulation conditions. In addition, the improvement assessed by Y-BOCS scores during the On-Stimulation conditions was positively correlated with PET signal changes at the boundary of the orbitofrontal cortex and the medial prefrontal cortex, between PET signal changes and the Y-BOCS scores modifications in On-Stimulation status. CONCLUSION: This study suggests that the therapeutic effect of STN DBS is related to a decrease in prefrontal cortex metabolism.