Compare the Effect on Cognitive Functioning of Two Formulations of Seroquel, Seroquel XR and IR in Patients With Stable Schizophrenia

You may be eligible if

• Provision of written informed consent prior to any study specific procedures
• Documented clinical diagnosis of schizophrenia, paranoid type, for at least 2 years before randomisation meeting the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV, American Psychiatric Association 2000) criteria of schizophrenia (DSM-IV codes 295.3) confirmed by MINI version 5.0
• Outpatient status at enrolment
• Dose of quetiapine IR or quetiapine XR unchanged during the last 56 days before randomisation
• Previous stable use of high dosage of benzodiazepines during one year or more
• Significant neurological medical history (complicated head trauma as judged by the investigator, epilepsy, meningo-encephalitis)
• Use of the following medication:
• other antipsychotic drug than quetiapine within 28 days prior to randomisation
• a depot antipsychotic injection within two dosing intervals (for the depot) before randomisation (Visit 2)
• other psychoactive drugs within 14 days prior to randomisation (hypnotic or anxiolytic drugs, other than those allowed)
• Use of concomitant therapy likely to affect cognition, Medication prohibited 28 days prior to randomisation: benzodiazepines, amphetamines, reboxitin, atomoxinetine, buspiron, donepezil, duloxetine, galantamine, ginko biloba, memantine, methylphenidate, modafinil, rivastigmine, tacrine, smoking cessation therapy varencicline and any dosage form of nicotine replacement therapy. Medication prohibited 14 days prior to randomisation: irreversible monoamine oxidase inhibitors (MAOI), tricyclic antidepressants (TCA), biperiden, antoicholinergic agents (even if the indications are extra pyramidal symptoms or urinary symptoms)