Thank you both! You're right that Seroquel is commonly used for bipolar depression, in fact I believe it's one of the best-researched drugs for that purpose. At least for me it seems to be one of the more effective ones, although with the low dosage I was wondering whether that was just in my mind. I don't really know how I respond to higher dosages because I can't tolerate them.

You may be right that it helps mainly with anxiety. I'm the same way in that depression and anxiety often go hand in hand for me, and sometimes it's hard to keep them apart. The Seroquel has mostly helped reduce the feelings of despair, which now that you mention it might be anxiety-related. It doesn't really fix the anhedonia, the lack of motivation, the inability to concentrate, the fatigue, and so on. So in my mind it kind of partially suppresses some of the symptoms without really "fixing" the episode. Still, it at least provides a bit of temporary relief. Thanks for sharing your insights!