The goal of this clinical trial is to optimize the target brain areas for deep brain stimulation (DBS) for depression based on personalized brain imaging and stereo-electroencephalography（SEEG), to administer long-term DBS treatment in the target brain areas, to assess the effectiveness and safety of DBS for refractory depression and to validate the method of personalized optimization of DBS targets. The main questions it aims to answer are:
1. Where is the optimal DBS target brain region for each patient? 2. What are the optimal DBS parameters for each patient ? 3. What are the neural biomarkers of depression symptoms for each patient? 4. Are the optimized DBS strategies effective in treating refractory depression?
A psychiatrist-confirmed diagnosis of major depressive disorder in accordance with the Diagnostic And Statistical Manual Of Mental Disorders.5th Ed (DSM-V);
A psychiatric examination by two trained psychiatrists and a diagnosis consistent with the DSM-V;
A history of depression of at least 12 months duration in depressed patients (including MECT) who have failed to respond to a full dose and course of treatment with 2 or more antidepressants of different mechanisms;
A 17-item score on the HAMD scale ⩾ 20 at initial screening;
Persons with severe or unstable cardiac, hepatic, renal, endocrine, hematologic, and other medical disorders and co-morbidities with psychotic symptoms, including personality disorders diagnosed by history, questioning, and clinical examination;
Persons with psychiatric disorders other than depression (except generalized anxiety);
Persons with a history of substance abuse within 12 months; persons with a previous history of epilepsy, and persons with febrile convulsions in childhood;
Patients with a history of suicide attempts within the past 6 months or more than 2 suicide attempts within the past 2 years;