Table 1 Inclusion criteria

Diagnosis of DSM-IV-TR [52] of Bipolar I or Bipolar II disorder as verified by the semi-structured diagnostic interviews SCID [37] or MINI plus [36]. The diagnosis may be supported by information from significant others, and from hospital records. Angst's hypomania checklist [53] is used to increase the detection of hypomanic symptoms. SCID or MINI plus will be used to diagnose the patient.

ECT is indicated.

Severity: meet DSM-IV-TR criteria of depressive episode, MADRS [40] of 25 or above

Treatment resistance: None response to two trials (during lifetime) with mood stabilizers with proven efficacy in bipolar depression (lithium, lamotrigine, quetiapine, olanzapine) and/or antidepressants.

A trial is defined as at least 6 weeks in adequate or tolerated dose as reported by the patient, or patients that have been unable to comply with 6 weeks trials of mood stabilizer or an antidepressant.

None response: Less than 50% reduction in MADRS values or still meet DSM -IV-TR criteria of depressive episode

Inpatients the first week after start of treatment condition

The patients are to be treated by the psychiatrist at the hospital for the whole duration of the study (6 weeks)

Age ≥ 18

Patient competent to give informed consent according to the judgement of the clinician

Written informed consent

Patient sufficiently fluent in Norwegian language to ensure valid responses to psychometric testing (for patients enrolled to neuropsychological assessment: Norwegian as primary language or 12 years attendance of a Norwegian school)