Comparing the Effects of Sertindole and Olanzapine on Cognition (SEROLA)

Inclusion Criteria: * AnICD-10 schizophrenia diagnosis F20.0-F20.9. * Contraception. * A negative pregnancy test for women. * No known allergy to any of the substances in the study medication * Baseline QTc \< 450 milliseconds for men and \< 470 milliseconds for women * S-potassium and s-magnesium within normal reference range. * Suboptimally treated on current antipsychotic medication * Stable dosage of antidepressants and mood stabilizers one month before the inclusion * Signed informed consent and power of attorney Exclusion Criteria: * Withdrawal of consent * QTc prolongation \>500 milliseconds during the study * Patients with known clinical important cardiovascular disease * Significant substance abuse * Earlier partial or non-response in treatment or intolerability to sertindole or olanzapine. * Calgary Depression Scale score ≥ 7 * Treatment that interferes with the metabolism of sertindole or olanzapine, * Oxazepam, zopiclone or zolpidem treatment the last 48 hours before cognitive testing * Prescription of not-allowed medication, or a change in dosage of antidepressant, or mood stabilizers in the study period * Treatment with an anticholinergic after the first three weeks of the study * Somatic illness, as judged by investigator, interfering with cognition * Known risk of narrow angle glaucoma * Treatment with electroconvulsive therapy (ECT) the last three months before inclusion, or treatment with ECT in the study period * Treatment with clozapine or depot antipsychotics before inclusion