I had to look this up because I knew I had read something about this in one of my many bp books. This is what I found in Why Am I Still Depressed? by Jim Phelps, MD. The study he is referring to is linked below. He has a very extensive website, www.psycheducation.org, that contains a great portion of the book, but I wasn't able to find the diagram that I will try to describe from the book to you on the website itself. The diagram is on page 29 of the book if you get a look at it.

He says:

"Depression is by far the predominate symptom in bipolar disorder of all kinds [both bp I and bp II], but especially in the middle of the [bipolar] spectrum [which he basically says corrolates to bp II]. In this study [see link below for study], patients were found to have symptoms about half the time. In Bipolar I, depression accounted for about two-thirds of that symptomatic time. But in Bipolar II, over 90% of the time spent ill was due to depression. Bipolar disorder in the middle of the Mood Spectrum [again, basically bipolar II] is experienced almost entirely as depression! Manic-side symptoms account for only a very small fraction of the experience."

Pg. 12: "The suicide rate Bipolar II is as high as, and in some studies, higher than, in Bipolar I." (I couldn't find what studies he is referencing here though.)

http://archpsyc.jamanetwork.com/arti...ticleid=207252