Mental illness is USUALLY caused by a chemical imbalance in the brain. Take silly ol' me, for instance. I suffer from, believe it or not, depression. For the last 7 or so years, I have been on AD's, and am ok now - for now. However, it took me YEARS to start taking it regularly. It's because of the way that people look at you when you take AD's (Anti-depressants). There are horrible signs attached to anyone who needs them, and it makes you feel bad when you rely on them.
The reason why most people who suffer from schitzophrenia (sp?) is they get admitted to the hospital, get their meds all sorted out, hate the side effects, then, when feeling better, stop using them. Then they CRASH. Then, they go back to the hospital to get their balance sorted out again.... it's a horrible disease - ever see A Beautiful Mind? I think that anyone who wants to see what its like should see that. That is only one case of schitzophrenia - some think it's perfectly normal to walk outside naked! It's horrible to think about...
Not that I have schitzophrenia, or anything... he he...