Quetiapine Related Neurochemical Changes as Measured by Magnetic Resonance Spectroscopy in Schizophrenia

Inclusion Criteria: 1. Provision of written informed consent 2. A diagnosis of schizophrenia or schizoaffective disorder by Diagnostic and Statistical Manual of Mental Disorders- Fourth Edition (DSM-IV) 3. Females or males aged \> 20 and \< 65 years 4. Female patients of childbearing potential must be using a reliable method of contraception and have a negative urine human chorionic gonadotropin (HCG) test at enrolment 5. Able to understand and comply with the requirements of the study 6. Undergoing treatment with a conventional antipsychotic drug and is clinically stable Exclusion Criteria: 1. Pregnancy or lactation 2. Any DSM-IV Axis I disorder not defined in the inclusion criteria 3. Patients who, in the opinion of the investigator, pose an imminent risk of suicide or a danger to self or others 4. Known intolerance or lack of response to quetiapine, as judged by the investigator 5. Use of any of the following cytochrome P450 3A4 inhibitors in the 14 days preceding enrolment including but not limited to: ketoconazole, itraconazole, fluconazole, erythromycin, clarithromycin, troleandomycin, indinavir, nelfinavir, ritonavir, fluvoxamine and saquinavir 6. Use of any of the following cytochrome P450 inducers in the 14 days preceding enrollment including but not limited to: phenytoin, carbamazepine, barbiturates, rifampicin, St. John's Wort, and glucocorticoids 7. Administration of a depot antipsychotic injection within one dosing interval (for the depot) before randomisation 8. Substance or alcohol dependence at enrolment (except dependence in full remission, and except for caffeine or nicotine dependence), as defined by DSM-IV criteria 9. Opiates, amphetamine, barbiturate, cocaine, cannabis, or hallucinogen abuse by DSM-IV criteria within 4 weeks prior to enrolment 10. Medical conditions that would affect absorption, distribution, metabolism, or excretion of study treatment as judged by the investigator 11. Involvement in the planning and conduct of the study 12. Previous enrolment or randomisation of treatment in the present study. 13. Participation in another drug trial within 4 weeks prior enrolment into this study or longer in accordance with local requirements 14. Subjects with metal prosthesis such as cardiac valves etc 15. Severe neurological co-morbidity such as stroke, encephalopathy etc or medical conditions that will compromise on the safety of patients such as acute myocardial infarction, systemic infections etc as judged by the investigator