Identifying Local Field Potential Biomarkers for Treatment-Resistant Major Depression With Deep Brain Stimulation

Inclusion Criteria: * 1\) Participants in the study should sign a research informed consent form before starting any research-related procedures; 2) Participants must be between the ages of 16 and 30, regardless of gender; 3) Diagnosed with Major Depressive Disorder (MDD) according to the diagnostic criteria in the DSM-V; 4) Participants must have medical records of their current depressive episode that has lasted for ≥2 years, or recurrent episodes, with a minimum of 4 episodes (with the current episode lasting at least 1 year); 5) Have previously failed at least 3 courses of adequate antidepressant therapy, using 2 or more different classes of antidepressants; and have refused, been unable to tolerate, or found electroconvulsive therapy (ECT) to be ineffective; 6) Participants must have a HAMD-17 score of ≥20 or a MADRS score of ≥25; 7) Participants must be able to communicate effectively, and the participant and their legal guardian must sign a written informed consent form. Exclusion Criteria: * 1\) Participants with bipolar disorder, schizoaffective disorder, schizophrenia, or other psychotic disorders; 2) Severe personality disorders; 3) Severe physical diseases or organic brain diseases; 4) Participants with alcohol or substance abuse and dependence diagnosed within 1 year prior to screening according to DSM-IV criteria; 5) Participants with surgical contraindications, such as significant comorbid medical conditions or inability to discontinue anticoagulation medications; 6) Structural imaging abnormalities evident on MRI performed within 1 year prior to screening; 7) MRI contraindications (excluding DBS implantation or the device itself); 8) Pregnant or breastfeeding; 9) Participants who are enrolled in another study unrelated to the current study; 10) Any condition that may currently or potentially endanger the participant's safety or preclude their successful participation in the study (family support, medical, psychological, social, or geographic factors).