Patient description: A 46-year-old Asian woman with MDD complains of persistent feelings of sadness and loss of interest in daily activities. She states that her mood is still depressed most of the days. She complains of loss of energy and feelings of worthlessness nearly every day. She is on anti-depressants for the past 6 months, but the symptoms are still present. She does not drink alcohol or smoke. She used to exercise every day for at least 30 min., but she doesn't have enough energy to do so for the past 3 weeks. She also has some digestive issues recently. She is married and has 4 children. She is menopausal. Her husband was diagnosed with colon cancer a year ago and is undergoing chemotherapy. Her past medical history is unremarkable. Her family history is negative for any psychologic problems. Her HAM-D score is 20.

Clinical trial eligibility criteria: eligible ages (years): 18.0-65.0,  Major Depression Generalized Anxiety Disorder For in the study subjects must fulfil all of the following 1. Provision of written informed consent 2. A diagnosis of a current major depressive episode (n =20) or generalized anxiety disorder (n = 20) of at least 4 weeks duration, as defined by Diagnostic and Statistical Manual of Mental Disorders Fourth Edition (DSM-IV) and assessed on the SCID. Subjects may be included if they meet for double depression, i.e., current major depression with antecedent dysthymic disorder, major depression in partial remission or bipolar depression. MDD subjects must have a 24 item Hamilton Depression Rating Scale Score (HAM-D) at intake >/= 20. GAD subjects must have a Hamilton Anxiety Rating Scale Score (HAM-A) at intake >/= 20. Patients who meet for current GAD only during a current episode of MDD will be considered to have MDD, according to DSM-IV convention. 3. Females and/or males aged 18-65 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. All subjects must report BZ use more days than not persistent for more than 6 months and a stable regimen of mood stabilizers and/or antidepressant medication for at least 8 weeks. -  Any of the following is regarded as a criterion for from the study: 1. Pregnancy or lactation 2. Any DSM-IV Axis I disorder not defined in the 3. Axis II diagnosis of antisocial, schizotypal or severe borderline personality disorder(defined as patients who are high risk for being unable to complete the study due to hospitalization, suicide attempts, significant self-mutilation, or other self-injurious or destructive behavior). 4. Patients who, in the opinion of the investigator, pose an imminent risk of suicide or a danger to self or others 5. Known intolerance or lack of response to quetiapine fumarate as judged by the investigator 6. 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 7. Use of any of the following cytochrome P450 inducers in the 14 days preceding enrollment including but not limited to: phenytoin, carbamazepine, barbiturates, rifampin, St. John's Wort, and glucocorticoids 8. Administration of a depot antipsychotic injection within one dosing interval (for the depot) before randomisation 9. Substance or alcohol dependence at enrolment (except dependence in full remission, and except for caffeine or nicotine dependence), as defined by DSM-IV 10. Opiates, amphetamine, barbiturate, cocaine, cannabis, or hallucinogen abuse by DSM-IV within 4 weeks prior to enrolment 11. Medical conditions that would affect absorption, distribution, metabolism, or excretion of study treatment 12. Unstable or inadequately treated medical illness (e.g. diabetes, angina pectoris, hypertension) as judged by the investigator 13. Involvement in the planning and conduct of the study 14. Previous enrolment or randomisation of treatment in the present study. 15. Participation in another drug trial within 4 weeks prior enrolment into this study or longer in accordance with local requirements