I've had mixed states where I was both manic and depressed at the same time, and I've also had ultra rapid cycling, sometimes changing between moods several times in just a few short minutes. Everyone says that bipolar is over diagnosed and that rapid cycling is rare-they're wrong. Rapid cycling is very common, IMO. I've seen it both here online, and in one of my offline bipolar friends (he is definitely bipolar).

The difference I've heard between BPD and bipolar is that bipolar mood swings are usually untriggered, while BPD mood swings are related to something that happens in the environment. And I don't think that people with BPD get hypo/manic ever, just mood swings between depression, anxiety, and other negative states.

Sometimes I wonder if I've been mis-dx'd and if maybe I have BPD because I can really relate to a few of the symptoms (black and white thinking, poor sense of identity, etc.). I really, really don't want to have BPD because I know how they are treated. The stigma for someone with a personality disorder is like 10,000 times worse than what I have to deal with with my bipolar diagnosis.

Every pdoc and t I've asked tells me that I definitely have a mood disorder, not BPD. Most of them are puzzled by why I would even think I might have it. But I still wonder if maybe I was misdiagnosed. There is such a thing as a "quiet borderline"...

For anyone who is interested, here is an interesting article on the difference between bp and bpd, and why it may not even matter: borderline