[F-18] FDG PET study in obsessive-compulsive disorder. A clinical metabolic correlation study after treatment

Background. We used [F-18]FDG and PET in patients with obsessive-compulsive disorder (OCD) to evaluate cerebral metabolic involvement before and after treatment with serotonin-specific reuptake inhibitors. Method. In 11 untreated, drug-free adults, regional cerebral metabolic rate for glucose (rCMRglu) was compared with that of 15 age-matched normal controls. Results. rCMRglu values were significantly increased in the cingulate cortex, thalamus and pallidum/putamen complex. After treatment a significant improvement in obsessive-compulsive symptoms on the Y-BOC scale (t=3.59, P<0.01) was associated with a significant bilateral decrease of metabolism in the whole cingulate cortex (P<0.001). Clinical and metabolic data were significantly intercorrelated (Kendall's tau=0.65; P<0.01). Conclusions. These findings indicate that OCD is associated with functional hyperactivity of a selected neuronal network and that treatment to reduce symptoms may have a selective neuromodulatory effect on cingulate cortex.