Abnormal metabolic brain network in patients with refractory obsessive compulsive disorder: Modulation by capsulotomy

Objectives Whether a specific covariance brain network is present in patients with obsessive-compulsive disorder (OCD).

Methods 18F-FDG PET scans were performed in 3D mode on a Siemens ECAT EXACT HR+ in seven refractory OCD patients (age = 21.0 ± 4.8 yr; disease duration = 8.4 ± 2.4 yr) and eight age- and sex-matched healthy volunteers (age=21.5 ± 5.9 yr). All patients were scanned before (Pre-op) and after (Post-op) bilateral capsulotomy. Network analysis based on SSM/PCA was then conducted in the combined Pre-op and normal scans to identify spatial covariance patterns whose expressions can separate the OCD and control subjects. The expression of this covariance pattern was also computed in Post-op PET images to evaluate the specific effect of capsulotomy.

Results Network analysis disclosed a significant OCD-related metabolic covariance pattern (OCD-RP) marked by hypermetabolism bilaterally in the frontal cortex (including rectal, orbital and cingulate gyri), internal capsule, thalamus and cerebellum, covarying with bilateral hypometabolism in the supplementary motor cortex (BA 6) and parietal lobe (BA 7). OCD-RP expression was significantly elevated in the Pre-op OCD patients relative to the controls. This measure was significantly lower at Post-op (score = 0.89 ± 0.30) than at Pre-op (score =1.75 ± 0.57; p < 0.003) in the OCD patients. In addition, subject scores were positively correlated (R = 0.593; p = 0.025) with ratings of Yale-Brown Obsessive Compulsive Scale (Y-BCOS) in individual patients before capsulotomy. Capsulotomy decreased Y-BOCS scores by 51.33 %, with a trend association between clinical outcome and changes in network score.

Conclusions This study has demonstrated the existence of a unique metabolic brain network (OCD-RP) in patients with refractory OCD.

Research Support This work was supported by grants from the Natural Science Foundation of China (No.3080034)