Marijuana made my Manic depression psychosis episodes worse and more frequent, when I was smoking pot I was being hospitalized 5150 2-3 times a year, since I quit smoking pot years ago I don't even get hospitallized in fact my manic depression is in remission and I no longer get manic or depressed episodes. People that think mental illness and marijuana are a good mix are certifiable crazy IMHO.
What utter BS. Marijuana present a clear and present danger to people with mental illnesses or tendencies to develop such, and this has been demonstrated scientifically through reputable studies over and over. Pot heads are living in the dark, just waiting for their next fix.
Obviously, if you already have a particular medical condition MJ might aggravate it or interact with your medications that you are taking for it. Again, I agreed to that under the "brain damage" comment, lol. Someone suffering from manic depression doesn't have a "normal" brain, at least in terms of scientific terms, since it will show on MRI, etc.
If your problems are stress, anxiety, minor but chronic pain, or add/adhd it helps swimmingly though. There are no one size fits all solutions, but some plants are miracles and do great things... I will always consider MJ one of those because of the breadth of usefulness it has.