Does schizophrenia affect intelligence? or it affect it indirectly? or different people have different situations? thanks?

I am not sure that I really understand the question but let me say that intelligence is not a factor in developing schizophrenia. Untreated there is certainly potential for cognitive decline with schizophrenia. Continued treatment with medication is the best initial approach for schizophrenia and some of the newer atypical antipsychotic meds do better for cognition

Yes, unfortunately schizophrenia interferes with intellectual functioning to a degree that varies with each person. If you watch the movie, A Beautiful Mind, you will see how this affected a Nobel Prize winner whose discoveries occurred before he became ill. It is best to get treatment as soon as possible when symptoms appear. This should include extensive psychotherapy regardless of medication.