This is an open label pilot feasibility study that will recruit 15 participants. The purpose of the pilot study will be to evaluate the feasibility of open label Transcranial direct current stimulation (tDCS) in combination with computerized cognitive behavior therapy (cCBT) to maintain wellness following an acute course of Electroconvulsive therapy (ECT) for up to 6 months.

Home-based tDCS-cCBT will involve 30-min tDCS (3 days per week) for the first 3 months and once weekly for the subsequent 3 months, in combination with computerized CBT delivered through an online portal for the duration of tDCS each day. Subjects who miss 4 consecutive treatment days or 20 percent of total treatments will be excluded from the study as it is our intention to encourage compliance with the proposed treatments to maintain optimal wellness. All missed treatment days will be recorded in a log for each participant.

Aim 1. To investigate the effectiveness of maintenance tDCS-cCBT for patients with MDD who have responded to a successful acute course of ECT.

Hypothesis 1. tDCS-cCBT will effectively maintain treatment response in MDD in a manner that is non-inferior to that of maintenance ECT.

Inclusion Criteria:

1. History of Major Depressive Disorder with most recent episode treated with acute ECT at the Temerty Centre for Therapeutic Brain Intervention, CAMH.
2. Individuals capable to provide consent who are receiving care as outpatients, and are now remitters (defined by the 24-item Hamilton Rating Scale for Depression (HRSD-24) ≤ 10).
3. Age 18-85, inclusive.

Exclusion Criteria:

1. History of a DSM-IV substance use disorder within the past three months
2. Concomitant major unstable medical illness
3. Pregnancy or the intention to become pregnant during the study
4. DSM-IV diagnosis of any psychotic disorder, obsessive compulsive disorder, or post-traumatic stress disorder (current or within the last year) as confirmed by the Mini-International Neuropsychiatric Interview (MINI)
5. DSM-IV diagnosis of personality disorder as assessed by a study investigator
6. Baseline score of < 24 on the MoCA
7. Any significant neurological disorder (e.g., a space occupying brain lesion, a history of stroke, a cerebral aneurysm, a seizure disorder, Parkinson's disease, Huntington's chorea, multiple sclerosis, head trauma with loss of consciousness for greater than or equal to five minutes)
8. Presenting with a medical condition, a medication, or a laboratory abnormality that could cause a major depressive episode or significant cognitive impairment in the opinion of the investigator (e.g., hypothyroidism with low TSH, Cushing's disease)
9. Any intracranial implant (e.g., aneurysm clips, shunts, cochlear implants) or any other metal object within or near the head, excluding the mouth, that cannot be safely removed
10. Any dermatological disorder or any cuts/broken skin in the scalp region that may affect the safe delivery of the tDCS stimulus
11. Requiring a benzodiazepine with a dose equivalent to lorazepam 2 mg/day or higher or any anticonvulsant due to the potential of these medications to limit the efficacy of ECT
12. The inability to communicate in spoken and written English fluently enough to complete the neuropsychological tests due to a language barrier or a non-correctable clinically significant sensory impairment (i.e., cannot hear or see well enough to complete the neuropsychological tests).
13. Cognitive impairment or physical impairment such that they are unable to learn to, or physically unable to apply tDCS to their scalp without assistance (after training).