I've been smoking for eight years and have just recently begun to have what I guess are panic attacks. I can't predict when they'll happen (most of the time I toke, and I'm fine) or even if that's what is happening when I'm having one. Most recently, I went to the hospital because I was convinced something in my stomach had ruptured and that I was going to internally bleed to death. Turns out it was good that I went to the hospital, because though it was just a panic attack, I was actually severely dehydrated by the time I got there (from being sick for the past month). My personal theory on that aspect is that if there's something bothering you, even if it's on an unconscious level, it can still manifest itself quite easily when you alter your mind.
As far as marijuana contributing to/even causing psychotic breakdowns, I must say that I think it indeed can help worsen symptoms in someone who's developed schizophrenia. I know I've shared this before, but I have a friend who threw out moderation one summer and ate insane amounts of LSD. He then developed what I believe to be paranoid schizophrenia. Now whether it's just LSD-induced or he actually was going to develop it on his own, I don't know. But anyways, he was starting to improve after disappearing from all of our friends for awhile. One day, he seemed to be alright until he smoked some chronic. Then, it was like he was digressing back into that
state where he couldn't distinguish reality from his perception of reality.
I think in a person who's already mentally ill, absolutely marijuana can influence your mental state.
I've dealt with bipolar disorder and a number of other things, and I've just come to realize that sometimes it's going to affect me, and there's really nothing I can do about it unless I quit smoking, which I don't think is worth it. All I can say is exercise caution.