PCS in Severe Treatment Resistant Depression

This study is testing a small implantable device called PCS (Precision Closed-loop Stimulation) as a treatment for people with severe, long-lasting depression that has not responded to many other treatments. **You may be eligible if...** - You have been diagnosed with depression lasting 2 or more years - You have tried 4 or more different antidepressant medications without relief - You have had, or were offered and declined, electroconvulsive therapy (ECT, also called shock therapy) - Your depression score on a standard scale is high at the start of the study - You are enrolled in Medicare - You are able to have brain MRI scans and EEG sessions - You are under the regular care of a licensed psychiatrist **You may NOT be eligible if...** - You already have a deep brain stimulator or an active vagus nerve stimulator - You have a history of schizophrenia, psychotic disorder, or seizures - You have been actively suicidal recently or have made a suicide attempt in the past year requiring medical care - You have dementia or significant memory problems - You are pregnant or have a positive drug screen - The surgery poses too high a medical risk for you Talk to your doctor to see if this trial is right for you.