This study will investigate whether using oscillating TES (random noise stimulation) or intermittent tDCS will have greater antidepressant effects in depressed subjects, compared to standard tDCS.

Inclusion Criteria:

• Subject meets criteria for a DSM-IV Major Depressive episode.

Exclusion Criteria:

• Diagnosis (as defined by DSM-IV) of: any psychotic disorder (lifetime); bipolar disorder; eating disorder (current or within the past year); obsessive compulsive disorder (lifetime); post-traumatic stress disorder (current or within the past year); mental retardation.
• Subject has not responded adequately to standard tDCS or is not appropriate for trial of standard tDCS (eg depression too chronic in duration)
• Total MADRS depression score of 20 or more
• History of drug or alcohol abuse or dependence (as per DSM-IV criteria) within the last 3 months (except nicotine and caffeine).
• Inadequate response to ECT in the current episode of depression.
• Subject is on regular benzodiazepine medication which it is not clinically appropriate to discontinue.
• Subject requires a rapid clinical response due to inanition, psychosis or high suicide risk.
• Neurological disorder or insult, e.g., recent stroke (CVA), which places subject at risk of seizure or neuronal damage with TES.
• Subject has metal in the cranium, skull defects, or skin lesions on scalp (cuts, abrasions, rash) at proposed electrode sites.
• Female subject who is pregnant. However, women of child bearing age are eligible if they have the pregnancy test but will be excluded if they are sexually active and not using reliable contraception (urine test for pregnancy will be used if appropriate).