Cortical γ-Aminobutyric Acid Concentrations in Depressed Patients Receiving Cognitive Behavioral Therapy

Background Reduced γ-aminobutyric acid (GABA) concentrations have been reported in plasma, cerebrospinal fluid, and cortex of depressed subjects. Treatment with both electroconvulsive therapy (ECT) and selective serotonin reuptake inhibitors (SSRI) increased occipital cortex GABA concentrations in prior studies. The purpose of this study was to determine whether treatment of major depression with cognitive behavioral therapy (CBT) produces similar changes in cortical GABA concentrations. Methods Occipital cortex GABA concentrations were measured in eight subjects with Major Depressive Disorder prior to and after a course of CBT using proton magnetic resonance spectroscopy. Results The effect of CBT on occipital cortex GABA content was different than that seen for ECT and SSRI medication treatment of depressed patients. Conclusions This preliminary finding suggests CBT has a less robust effect on cortical GABA content than ECT and SSRI treatments and might indicate a difference between the mechanisms of antidepressant action.