Differences in Brain Glucose Metabolism Between Responders to CBT and Venlafaxine in a 16-Week Randomized Controlled Trial

Abstract

Objective: Neuroimaging investigations reveal changes in glucose metabolism (fluorine-18-fluorodeoxyglucose positron emission tomography [PET]) associated with response to disparate antidepressant treatment modalities, including cognitive behavior therapy (CBT), antidepressant pharmacotherapies, and deep brain stimulation. Using a nonrandomized design, the authors previously compared changes following CBT or paroxetine in depressed patients. In this study, the authors report changes in fluorine-18-fluorodeoxyglucose PET in responders to CBT or venlafaxine during a randomized controlled trial. Methods Subjects meeting DSM-IV-TR criteria for a major depressive episode and a diagnosis of a major depressive disorder received a fluorine-18-fluorodeoxyglucose PET scan before randomization and after 16 weeks of antidepressant treatment with either CBT (N=12) or venlafaxine (N=12). Modality-specific and modality-independent regional brain metabolic changes associated with response status were analyzed. Results: Response rates were comparable between the CBT (7/12) and venlafaxine (9/12) groups. Response to either treatment modality was associated with decreased glucose metabolism bilaterally in the orbitofrontal cortex and left medial prefrontal cortex, along with increased metabolism in the right occipital-temporal cortex. Changes in metabolism in the anterior and posterior parts of the subgenual cingulate cortex and the caudate differentiated CBT and venlafaxine responders. Conclusions: Responders to either treatment modality demonstrated reduced metabolism in several prefrontal regions. Consistent with earlier reports, response to CBT was associated with a reciprocal modulation of cortical-limbic connectivity, while venlafaxine engaged additional cortical and striatal regions previously unreported in neuroimaging investigations.