Question: What is the difference between bipolar disorder and major depression or anxiety disorders?
Answer: I think the best way to understand this is that major depression is one pole of an affective disorder. A bipolar person will have both highs and lows -- or a manic component as well as a depressed component. There are people who have just unipolar depressions and never have any manias.
Anxiety can be a part of either depression or bipolar disorder, but it can also exist on its own. The issues with both bipolar and unipolar or major depression is that it's a mood problem. And so, perhaps the way to tease these all apart is to say that bipolar and unipolar, mood has to be there. Anxiety disorder, anxiety has to be there. But anxiety can be present along with the mood problems. And presumably, if mood problems are present along with the anxiety, then you'd be more likely to diagnose the mood disorder, the bipolar or the unipolar depression.