• obsessive–compulsive disorder;
  • neuropsychology;
  • positron emission tomography

Objective:  The study was designed to elucidate regional brain metabolic changes according to a treatment and their relationship with neuropsychological performance changes in obsessive–compulsive disorder (OCD).

Method:  Cerebral glucose metabolic rates were repeatedly measured before and after treatment in 10 patients with OCD using [18F]-2-fluoro-deoxyglucose positron emission tomography (PET). They were compared on a voxel-basis, and the correlations were counted between the regional metabolic changes and the degree to improvement on the neuropsychological assessments.

Results:  After treatment, the patients showed significant (P < 0.005, two-tailed) regional metabolic changes in multiple brain areas involving frontal–subcortical circuits and parietal–cerebellar networks. Especially, the metabolic changes of the putamen, the cerebellum, and the hippocampus were significantly correlated with the improvement of the immediate- and delayed-recall scores of the Rey-Osterrieth Complex Figure Test (RCFT).

Conclusion:  These results suggest a possibility that metabolic changes of frontal–subcortical and parietal–cerebellar circuit changes may underlie cognitive improvements in patients with OCD.