FDG-PET predictors of response to behavioral therapy and pharmacotherapy in obsessive compulsive disorder

In subjects with obsessive-compulsive disorder (OCD), lower pre-treatment m etabolism in the right orbitofrontal cortex (OFC) and anterior cingulate gy rus (AC) has been associated with a better response to clomipramine. We sou ght to determine pre-treatment metabolic predictors of response to behavior al therapy (BT) vs, pharmacotherapy in subjects with OCD. To do this, [F-18 ]fluorodeoxyglucose positron emission tomography scans of the brain were ob tained in subjects with OCD before treatment with either BT or fluoxetine. A Step-Wise Variable Selection was applied to normalized pre-treatment gluc ose metabolic rates in the OFC, AC, and caudate by treatment response (chan ge in Yale-Brown Obsessive-Compulsive Scale) in the larger BT group. Left O FC metabolism (normalized to the ipsilateral hemisphere) alone was selected as predicting treatment response in the BT-treated group (F = 6.07, d.f. = 1,17, P = 0.025). Correlations between normalized left OFC metabolism and treatment response revealed that higher normalized metabolism in this regio n was associated with greater improvement in the BT-treated group (tau = 0. 35, P = 0.04), but worse outcome (tau = - 0.57, P = 0.03) in the fluoxetine -treated group. These results suggest that subjects with differing patterns of metabolism preferentially respond to BT vs. medication. (C) 1998 Elsevi er Science Ireland Ltd.