Spaced Transcranial Direct Current Stimulation for Treatment-Resistant Depression: A Home-Based Feasibility and Safety Study

Inclusion Criteria: 1. People between the ages of 18 and 85 at the time of screening. 2. Currently diagnosed with Major Depressive Disorder (MDD) as measured by the MINI and a MADRS score of ≥ 20. 3. Safe for TMS as measures by the TMS Adult Safety Screening (TASS). 4. Medical records confirming a history of failing to achieve clinical response to an adequate antidepressant trial as defined an Antidepressant Treatment History Form (ATHF) score ≥ 3 or ) or shown intolerance to at least two inadequate trials (score 1 or 2), without psychiatric illness due to a general medical condition. 5. Stable internet connection and a device compatible with Microsoft Teams. Exclusion Criteria: 1. History of psychotic or bipolar disorder or depression with psychotic features; 2. Significant borderline personality disorder; 3. Significant comorbid obsessive-compulsive or post-traumatic stress: 4. Current moderate or severe substance use disorder or demonstrating signs of acute substance withdrawal; 5. Clinically significant suicidality disorder; 6. Chronic depression (defined as of over 5 years duration); 7. Pregnancy or lactation, lack of adequate birth control in women of childbearing age; 8. History of significant neurologic disease, including dementia, Parkinson's or Huntington's disease, brain tumor, seizure disorder, subdural hematoma, multiple sclerosis, or history of significant head trauma with persistent symptoms; 9. Unstable medical illness; 10. Contraindication to receiving tDCS (e.g., ferromagnetic implant, history of seizure, known brain lesion); 11. History of TMS (greater than 15 sessions) without a clinically meaningful response.; History of ketamine (greater than 4 sessions) without a clinically meaningful response; 12. Require a benzodiazepine with a dose \> lorazepam 2 mg/day; 13. dermatological conditions contraindicating tDCS; 14. Non-correctable sensory impairments; 15. Inability to consent or participate as an outpatient