As a nurse and an EMT I’ve dealt with a fair number of patients with bipolar disorder or schizophrenia.
I’ve seen a few smart people, but no one who impressed me as brilliant. Schizophrenia usually leads to a poverty of thought, so if you met someone who was schizophrenic they would not likely appear very intelligent, but they might have before the disease began. I’ve seen more people with diagnosed developmental disabilities.
It is true that intelligent people are more likely to be able to manage their illness, and stay out of the hospital. Some of the medications are sedating, dulling, even stupefying. It’s one reason why people stop taking them.
“Schizophrenia usually leads to a poverty of thought”
Oh, thank God...we’re safe.