Effects of Erythropoietin on Cognition and Neural Activity in Mood Disorders

Inclusion Criteria: * Fluent Danish skills and objective cognitive impairment (a total score below cutoff, or scores below cutoff on a minimum of two out of the five subtests (Verbal Learning Test - Immediate, Working Memory Test, Verbal Fluency Test, Verbal Learning Test - Delayed and Processing Speed Test) on the Screen for Cognitive Impairment in Psychiatry - Danish version (SCIP-D). * Patients must meet the ICD-10 diagnosis of BD (type I and II) or recurrent depressive disorder confirmed using the Schedules for Clinical Assessment in Neuropsychiatry (SCAN) interview. * Healthy people are eligible even when diagnosed with a less severe mental disorder defined as ICD-10 codes ≥F40. Exclusion Criteria: * Schizophrenia or schizoaffective disorder * Current alcohol or substance misuse disorder (3 months prior to inclusion) * Daily use of benzodiazepines \> 22.5 mg oxazepam * Diabetes * Kidney disease * Renal failure * Untreated/insufficiently treated arterial hypertension * Heart diseases (previously diagnosed or abnormal ECG findings during screening) * Previous serious head trauma * Neurological illness (including dementia) * Previous or current epilepsy in patient or first degree family * Malignancies or thromboses * Known allergy or antibodies against erythropoietin * Initial hematocrit \> 50% (males) or \> 48% (females) * Initial thrombocyte numbers over normal (\>400 billions/L) * Initial reticulocyte numbers \<1‰ * Contraindications against prophylactic thrombosis tr…