After the baseline assessment and prior to the initiation of treatment, first fMRI session will be performed. Then quetiapine XR will be initiated at 50mg/day the first 2 days and 150 mg/day on day 3 and titrated to 300mg/day by day 4, and citalopram will be initiated at the dose of 10 mg /day and titrated to 20 mg/day by day 4. The patients in both treatment arms will continue this dosage until the completion of the study protocol 8 weeks later. For the patients who could not tolerate or develop adverse effects, the quetiapine dose will be reduced to 150 mg/day and citalopram dose will be reduced to 10 mg/day. The patients who could not tolerate quetipine 150 mg/day and citalopram 10 mg/day will be terminated from the study.During their participation in the study, patients will undergo a clinical assessment at week one after the titration of quetiapine and citalopram and a second fMRI session. Depressive and anxiety symptoms will be rated using HRSD and HAM-A. Then, patients will be evaluated every two weeks and at the week 8 using HRSD and HAM-A. At week 8, a third fMRI session will be performed. Adverse effects will be recorded. The patients who could not tolerate any of the study medications will be terminated from the study