I have never had circumstantial speech issues. I definitely have bipolar disorder; I was diagnosed 25 years ago and have been rediagnosed several times since.

In my experience of working with people with mental illness, being married to a man with mental illness (OCD), and just life in general, circumstantial speech is typical of someone with OCD and/or an OC personality, or some who has schizophrenia. I am not clear on what circumstantial speech has to do with bipolar disorder. Some people, when manic, have pressured speech, but that's somewhat different.