Clinical Research Directory

Inclusion Criteria: * Age between 18 and 65 years * Diagnosis of Major Depressive Disorder according to DSM-5 criteria * Inadequate response to at least one adequate antidepressant treatment trial * Hamilton Depression Rating Scale (HAM-D) score ≥14 at baseline * Stable dose of antidepressant medication for at least 4 weeks prior to study entry * Ability to provide written informed consent Exclusion Criteria: * History of bipolar disorder, schizophrenia, schizoaffective disorder, or psychotic depression * Current substance use disorder * Neurological disorders that may affect brain function (e.g., epilepsy, multiple sclerosis, dementia, Parkinson's disease) * History of epileptic seizures * Severe head trauma * Presence of metal implants in the head or neck region * Cochlear implants * Cardiac pacemaker or implanted electronic devices * History of deep brain stimulation or vagus nerve stimulation * Previous neurosurgical procedures * Pregnancy or breastfeeding * Use of medications that may significantly affect neuroendocrine or inflammatory markers (e.g., corticosteroids, immunomodulators) * Endocrine disorders affecting the hypothalamic-pituitary-adrenal axis (e.g., Cushing's syndrome, Addison's disease, thyroid disorders) * Autoimmune diseases (e.g., systemic lupus erythematosus, rheumatoid arthritis, Hashimoto thyroiditis) * Recent surgery or acute infection * Active suicidal crisis, severe agitation, or inability to comply with study procedures