Answer:
It's primary use is for augmentation of antidepressant treatment of Major Depressive Disorder, as well as treatment of Bipolar Disorder and Schizophrenia.
Interestingly enough, however, Seroquel and Seroquel XR have anxiolytic properties. This makes these medications quite useful in treating individuals dealing with depressive episodes associated with anxiety - whether as a component of bipolar depression or major depressive disorder. However, Seroquel and Seroquel XR are not indicated for the PRIMARY treatment of anxiety disorders (which do not occur concommitantly with affective or psychotic disorders).
The anxiety-reducing properties of Seroquel and Seroquesl XR are a function of both antihistaminic effects of the molecule, as well as serotonergic effects.