The objectives of this study are to evaluate the efficacy and safety of quetiapine extended release tablet versus placebo as adjunct to selective serotonin reuptake inhibitors/serotonin/norepinephrine reuptake inhibitors (SSRI/SNRI) in the augmentation treatment of patient with primary anxiety disorders or mood disorders with co-morbid anxiety symptoms.

Inclusion Criteria:

• Provision of written informed consent
• A diagnosis of primary anxiety disorder or mood disorder with co-morbid anxiety symptoms by Diagnostic and Statistical Manual of Mental Disorders-Fourth Edition (DSM-IV)
• A 14-item Hamilton Anxiety Scale (HAM-A)>= 14
• Subject have received single antidepressant at a therapeutic dose for at least 6 weeks
• Male or female aged 18-65 years
• Female patients of childbearing potential must be using a reliable method of contraception and have a negative urine human chorionic gonadotropin (HCG) test at enrollment
• Able to understand and comply with the requirements of the study and sign informed consent

Exclusion Criteria:

• Pregnancy or lactation

• Any DSM-IV Axis I disorder not defined in the inclusion criteria.

• Receiving any anti-psychotic 7 days prior to entering the study

• Patients who, in the opinion of the investigator, post an imminent risk of suicide or a danger to self or others

• Known intolerance or lack of response to quetiapine fumarate, as judged by the investigator

• Use of any of the following cytochrome P450 3A4 inhibitors in the 14 days preceding enrollment including but not limited to: ketoconazole, itraconazole, fluconazole, erythromycin, clarithromycin, troleandomycin, indinavir, nelfinavir, ritonavir, fluvoxamine and saquinavir

• Use of any of the following cytochrome P450 3A4 inducers in the 14 days preceding enrollment including but not limited to: phenytoin, carbamazepine, barbiturates, rifampin, St.John's Wort, and glucocorticoids

• Administration of a depot antipsychotic injection within one dosing interval (for the depot) before randomization

• Substance or alcohol dependence at enrollment (except dependence in full remission, and except for caffeine or nicotine dependence), as defined by DSM-IV criteria

• Opiates, amphetamine, barbiturate, cocaine, cannabis, or hallucinogen abuse by DSM-IV criteria within 4 weeks prior to enrollment

• Medical conditions that would affect absorption, distribution, metabolism, or excretion of study treatment

• Unstable or inadequately treated medical illness (e.g. congestive heart failures, angina pectoris, hypertension) as judged by the investigator

• Involvement in the planning and conduct of the study

• Previous enrollment or randomization of treatment in the present study

• Participation in another drug trial within 4 weeks prior enrollment into this study or longer in accordance with local requirements

• A patient with Diabetes Mellitus (DM) fulfilling one of the following criteria:

  • Unstable DM defined as enrollment glycosylated hemoglobin(HbA1c)> 8.5%
  • Admitted to hospital for treatment of DM or DM related illness in past 12 weeks.
  • Not under physician care for DM
  • Physician responsible for patient's DM care has not indicated that patient's DM is controlled
  • Physician responsible for patient's DM care has not approved patient's participation in the study
  • Has not been on the same dose of oral hypoglycaemic drug(S) and/or diet for the 4 weeks prior to randomization. For thiazolidinediones(glitazones) this period should not be less than 8 weeks
  • Taking insulin whose daily dose on one occasion in the past 4 weeks has been more than 10% above or below their mean dose in the preceding 4 weeks

• An absolute neutrophil count (ANC) of <= 1.5x10(9) per liter