Theta Burst StimulationBiomarkers of Theta Burst Stimulation in Major Depressive Disorder

Inclusion Criteria:

1. Participant must meet the DSM-5 diagnostic criteria for single-episode Major Depressive Disorder (MDD).
2. Participant must have failed to respond to >1 but <4 classes of oral antidepressant treatments in the current episode of depression.
3. Participant must have a HAMD total score of at least 18

Exclusion Criteria:

1. The participant's depressive symptoms have previously demonstrated nonresponse to:

• An adequate course of rTMS/TBS over DLPFC in the current major depressive episode, defined as at least 3 weeks of treatment, 5 times weekly
• An adequate course of treatment with electroconvulsive therapy (ECT) in the current major depressive episode, defined as at least 7 treatments with unilateral/bilateral ECT.

2. Participant has received vagal nerve stimulation (VNS) or has received deep brain stimulation (DBS) in the current episode of depression.
3. Participant has a current or prior DSM-5 diagnosis of Axis I comorbidities, including psychosis, bipolar disorder, obsessive compulsive disorder, based upon clinical assessment and confirmed by the MINI.
4. Participant has a current or prior DSM-5 diagnosis of Axis II comorbidities, including severe borderline personality disorders, antisocial, schizotypal, schizoid personality disorders based upon clinical assessment and confirmed by the MINI.
5. Participant has severe suicidal ideation/plan/ intent.
6. Participant has a history of moderate or severe substance or alcohol use disorder according to DSM-5 criteria.
7. Participant has a current or past history of seizures and neurological problems, e.g. head injury, stroke, progressive neurological disorder and complicated and unstable medical disorders, e.g. cardiovascular-related conditions, diabetes.