Recurrances are actually very likely, I believe. Though I have read of people with bipolar disorder only having a few episodes in their lives, I believe that is definitely not the norm. There are many of us with bipolar disorder that have numerous episodes, sometimes more than one can remember. My bipolar illness worsened as I aged from being unmedicated.

If a person has schizoaffective disorder, I'd think that the illness course would be even worse, at least as the schizophrenic symptoms go. That's something to ask a mental health professional. If a doctor says the schizophrenic symptoms were likely only caused by marijuana abuse, that could yield a possibly different answer. Again, your sister's psychiatrist should be the one to answer this question. Is she still using marijuana?

My husband's nephew was hospitalized years ago and diagnosed with schizophrenia, but not bipolar disorder, but later it was found that he didn't have schizophrenia, but that severe marijuana abuse was indeed the culprit for his experience. He stopped using marijuana completely and the hallucinations disappeared. For this reason, I urge people to not use marijuana, especially not without a doctor's direction or in extreme moderation.