I'm fascinated by this thread, and surprised I hadn't noticed it yet.
About five years ago, I was talking to a girlfriend who has a son who was diagnosed with Bipolar Disorder. He was nine years old.
I revealed to her that despite the fact that I have a few "letters" after my own name,
I believe everything I have ever done was a deliberate choice. I have done some really fucking stupid things, but in every instance, before I did them, I thought "this probably isn't a good idea," then went ahead and did them anyway.
My friend was appalled! She insisted over and over to me that her son had absolutely no control over his behavior while manic, or depressed, or in a "mixed state."
Now her son is 14 and
violently out of control and getting into all kinds of trouble. I believe it is a direct result of her (and his medical providers) having convinced him that he is not responsible for his own behavior.
A Psychiatrist once explained to me that people with mental illnesses are still primarily... people (imagine that!) with their own inherent personalities. When we lose inhibitions, what tends to emerge is our true nature.
We are who we are. Some of us have a legitimate medical condition, and some do not. But in the vast majority of cases, I believe everything we do is a choice, regardless of the letters after our names.