Relationship of Peripheral Inflammatory and Neuroprotective Biomarkers With Response to Intermittent Theta Burst Stimulation in Treatment-Resistant Depression

Inclusion Criteria Treatment-Resistant Depression Group: Age between 18 and 55 years. Male or female participants. Diagnosis of Major Depressive Disorder according to DSM-5-TR criteria. Inadequate response to at least two antidepressant treatments administered at adequate doses and durations. Eligible for transcranial magnetic stimulation (TMS) treatment. Able and willing to provide written informed consent. Able to complete neuropsychological assessments. Able to attend study visits and complete the treatment protocol. Healthy Control Group: Age between 18 and 55 years. Male or female participants. No current DSM-5-TR psychiatric disorder. Able and willing to provide written informed consent. Able to complete neuropsychological assessments. Exclusion Criteria Schizophrenia, bipolar disorder, organic mental disorders, or other major psychiatric disorders. History of epilepsy, brain tumor, severe head trauma, or significant neurological disease. Any contraindication to TMS. Presence of intracranial metal implants, cardiac pacemakers, cochlear implants, or other incompatible implanted devices. Active infection. Autoimmune disease or chronic inflammatory disease. Electroconvulsive therapy, deep brain stimulation, or vagus nerve stimulation within the previous 5 years. Previous intravenous or intranasal ketamine treatment. Pregnancy or breastfeeding. Active alcohol or substance use disorder. Inability to comply with study procedures. Inability to tolerate the iTBS protocol. Withdrawal of informed consent at any stage of the study.