Transcranial Direct Current Stimulation in Major Depression

Noninvasive transcranial direct current stimulation (tDCS) is a low-intensity neuromodulation technique of minimal risk that has been used as an experimental procedure for reducing depressive symptoms and symptoms of other brain disorders. Though tDCS applied to prefrontal brain areas is shown to reduce symptoms in some people with major depressive disorder (MDD), the extent of antidepressant response often differs. Methods that map current flow directly in the brain while a person is receiving tDCS and that determine how functional neuroimaging signal changes after a series of tDCS sessions may help us understand how tDCS works, how it can be optimized, and if it can be used as an effective intervention for reducing depressive symptoms. We will investigate these questions in a two-part randomized double blind exploratory clinical trial. The first part of the trial will compare how current flow and functional imaging signal differs in the brain when using tDCS with more focal stimulation, called high definition (HD) tDCS, compared to conventional tDCS (C-tDCS) or sham (non-active) tDCS in patients with MDD. Sixty people with depression (20 in each group) will be randomized to receive either HD-tDCS, C-tDCS or sham-tDCS for a total of 12 sessions each lasting 20 minutes occurring on consecutive weekdays. At the first and last session, subjects will receive 20-30 minutes of active or sham tDCS in the MRI scanner, which will allow us to map tDCS currents, and track changes in regional cerebral blood flow (rCBF) pre-to- post treatment using completely non-invasive methods. At the first and last session and mid-way through the trial, participants will also complete a series of clinical ratings and neurocognitive tests