Neuroimaging in Patients Undergoing TMS for Depression

Significance: There are few therapeutic options for individuals with treatment resistant depression (TRD). One recently developed approach is rTMS over left dorsolateral prefrontal cortex. Recent studies have demonstrated overall antidepressant benefit of rTMS in patients who fail to respond to a trial of antidepressant medication (1, 2, 3). Nevertheless, for many patients the response is incomplete, suggesting the need for further optimization. One potential cause of heterogeneous response might relate to individual differences in brain anatomy and connectivity patterns. At present, the rTMS stimulation site across subjects is based upon fixed location relative to motor cortex. Potentially, however, the approach could be optimized by stimulating based upon individual brain functional connectivity pattern. The present project will collect pre- and post-treatment brain functional connectivity measures in a group of patients who will be receiving independent clinical rTMS for resistant depression, a connectivity-based targeting approach will be applied at the single-subject level to individualize therapy in those patients who do not respond to standard approaches. Patients will be divided in 2 groups. Group 1 (N=30) will be depressed patients undergoing standard TMS for the first time. Group 2 (N=30) constitutes those who have previously demonstrated that they do not respond to standard TMS. MDD patients prescribed to receive standard TMS for the first time (group 1) will have resting-state FMRI in order to see if their responsiveness based on the functional connectivity maps can be predicted. Non-responders to standard TMS approaches (Group 2) will be randomized (3:2) to either receive targeted (N=18) or standard (N=12) repetitive TMS (rTMS) treatments. A connectivity-based targeting strategy will be used on patients undergoing targeted rTMS to optimize target for focal brain stimulation. Raters and patients in group 2 will be kept blinded to the treatment assignment. All patients referred from the ongoing treatment study will be assessed by 3 tesla brain MRI, Magnetic Resonance Spectroscopy (MRS) and Cerebral Blood Flow/Volume (CBF/CBV) procedures at baseline and immediately following the final treatment.