The purpose of this study is to determine functional and structural changes in brain following treatment of severe depression with electroconvulsive therapy with correlation to clinical outcome. Our hypothesis is that there are state-dependent changes in functional connectivity within specific neurocircuits systems, as well as structural plasticity changes in hippocampus, when recovering from depression.

The study is a prospective, within-subject, observational follow-up study in individuals with depression who receive electroconvulsive therapy (ECT)at a psychiatric clinic. We will use a consecutive sampling method and patient referred for ECT by their psychiatrist will be screened for inclusion and asked for participation. Both in - and outpatients can be included. At three occasions (before treatment, after four week and after three months) patients will be assessed with clinical ratings, cognitive tests, functional and structural magnetic resonance imaging and biomarkers for cell proliferation.

Inclusion Criteria:

• major depressive disorder
• depressive episode in bipolar disorder
• age 18 - 65 years

Exclusion Criteria:

• alcohol- and/or drug dependence or abuse in the past 3 months
• severe/life-threatening medical disease
• pregnancy
• type I diabetes
• neurodegenerative disorder
• inability to give written informed consent to participation in the study
• contradiction to MRI scanning.

Patients with depression referred for ECT.