Among antidepressant treatments, electroconvulsive therapy (ECT) remains the most effective. However, patient concerns with cognitive side effects have encouraged trials of new, non-convulsive forms of mild brain stimulation such as transcranial Direct Current Stimulation (tDCS). Our past and present studies of tDCS suggest that it has antidepressant effects and is safe, painless and well tolerated. However, not all patients may have an adequate response, raising the need to find ways of optimising efficacy. This clinical pilot study will examine the feasibility and safety of combining tDCS with a cognitive training task which engages the same brain region targeted by tDCS for treatment of depression.

Inclusion Criteria:

1. Participants are aged 18-65 years.
2. Participant meets criteria for a DSM-V Major Depressive episode. Criteria are as follows: Five or more symptoms present during the same 2-week period, including either 1 or 2: 1) depressed mood, 2) loss of interest or pleasure, 3) significant weight loss or gain, 4) insomnia or hypersomnia, 5) psychomotor agitation or retardation, 6) fatigue or loss of energy, 7) feelings of worthlessness or excessive or inappropriate guilt, 8) diminished ability to think concentrate or make decisions, and 9) recurrent thoughts of death, recurrent suicidal ideation, suicide attempt or plan.
3. MADRS score of 20 or more.
4. Right handed
5. A history of non-response to ≥ 2 adequate trials of antidepressant medication treatment.

Exclusion Criteria:

1. DSM-V psychotic disorder.
2. Drug or alcohol abuse or dependence (preceding 6 months).
3. Inadequate response to ECT (current episode of depression).
4. Regular benzodiazepine medication
5. Rapid clinical response required, e.g., due to high suicide risk.
6. Clinically defined neurological disorder or insult.
7. Metal in the cranium, skull defects, or skin lesions on scalp (cuts, abrasions, rash) at proposed electrode sites.
8. Pregnancy.