Adjunctive D-Cycloserine in Major Depressive Disorder

Major Depressive Disorder (MDD) is a common and debilitating illness. For an unacceptable proportion of patients, depressive symptoms remain impairing despite multiple treatments. Increasingly, non-invasive brain stimulation techniques are being explored as a means of targeting specific brain regions and networks that are implicated in depression. Repetitive transcranial magnetic stimulation (rTMS) is the non-invasive stimulation technique with the largest evidence base in MDD. Targeting the dorsolateral prefrontal cortex (DLPFC) with rTMS has proven an effective treatment for MDD, however as many as 2/3 of patients will not experience substantial improvement. Adjunctive agents are a potential strategy to improve patient outcomes. The objective of the proposed study is to determine the efficacy of adjunctive D-cycloserine with rTMS directed to the left dorsolateral prefrontal cortex (DLPFC) in acute Major Depressive Episodes. The investigators propose to utilize a stimulation protocol called the intermittent theta-burst protocol to study rTMS in conjunction with D-cyloserine using a randomized double-blind, placebo-controlled design with allocation concealment. Patients with Major Depressive Disorder will be randomized to receive 1) rTMS+cycloserine, or 2) rTMS+placebo in a 1:1 ratio for two weeks (10 sessions). At the conclusion of the 2-week blinded augmentation phase, patients will continue to receive two weeks of rTMS without an augmentation agent or placebo. The primary outcome measures will be improvement in depression as measured by change in Montgomery Asberg Depression Rating Scale (MADRS). In addition, the investigators will also be looking at the improvement of other clinical outcome measures, quality of life and changes in brain functional dynamics, as assessed with functional Magnetic Resonance Imaging (MRI), and metabolites, as assessed by Magnetic Resonance (MR) Spectroscopy.