from either disorder or even a combination of the two.
It has been estimated that around 85% of all major (as opposed to bipolar disorder, a.k.a. manic depression) cases are accompanied by symptoms of mild to acute anxiety. For the most part, the anxiety portion of combination symptoms comes as a diagnosis of generalized anxiety disorder. In this same study, about 35% of this group had symptoms of panic disorder.
Because anxiety and go together so often they are generally considered to be the linked twins as far as the biggie mood disorders go. Unfortunately is takes longer to treat when it is accompanied by anxiety. Many of those who have suffered from with anxiety claim that it is the anxiety that they feel is the difficult and lingering part of their ailment.
Here are some more depression articles...