The primary objective is to test the hypothesis that Quetiapine XR (Extended Release) monotherapy and adjunctive therapy is effective in the acute treatment of bipolar depression and comorbid generalized anxiety disorder in patients with bipolar disorder with or without a substance use disorder. The secondary aim is to generate an estimate of effect size to power a definitive large-scale, multi-site collaborative R01 and to configure the use of the primary and secondary outcome measures in the definitive large-scale study.