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

Abstract

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.

Figure 1. Significantly increased metabolic activity in the OCD patient group compared with healthy volunteers in the left inferior frontal gyrus (BA 45), associated with a decrease in activity in the left insula (BA 13) (p<0.001 uncorrected, colour bar represents t values).

Sagittal, coronal and transversal views in projection onto brain slices of a standard MRI (x/y/z coordinates according to Talairach atlas).

Figure 2. Significantly decreased metabolic activity in the OCD patient group compared with healthy volunteers in the right cingulate gyrus (BA 31) (p<0.001 uncorrected, colour bar represents t values).

Sagittal and coronal views in projection onto brain slices of a standard MRI (x/y/z coordinates according to Talairach atlas).