I'm wondering whether or not something such as, say, Mercury poisoning could be involved? There's no way that I see, IMO, she could have gotten through such training and screening as she did over the course of 25+ years (Naval Academy, Navy Career, Shuttle crew) with as many screws loose as this behavior appears to represent.
I'm not sure. While it's possible...there are a lot of people that have gone up in space...mental health issues can happen to any body at any age...including astronauts.
The stigma of mental health issues is still present in civilian society...its a lot worse in the military, and she's undoubtedly a disciplined person. She may have gotten very good at concealing her loose screws.
We largely know about the story because she was an astronaut and a high ranking military officer. Had she been an ordinary citizen and done this...especially where no one was killed...this probably would have been just another crime in a rather violent city.