The primary objective is to examine the beneficial effect of quetiapine augmentation of first-line antidepressants in refractory depression with co-morbid anxiety, compared to placebo. It is hypothesized that significant improvement on depression and anxiety symptoms will be seen as evidenced by reduction in Hamilton Depression Rating Scale (HAMD-17) and Hamilton Anxiety Scale (HAMA) scores after the 12 week treatment period for those who received Quetiapine XR augmentation compared to those who received placebo.2.2