If anyone has a link to the Finland studies that John mentions, I would like to take a look.
People with schizophrenia were treated with psychotherapy only in quite a number of facilities in the US and it was a total disaster. I grant that the treatment approach is key to success or failure of treatment, so I'd love to see those studies.
One of the main theories of how schizophrenia symptoms occur is that there is a deficit of dopamine to certain areas of the brain. That causes social isolation and decreased motivation. The brain in an attempt to compensate increases the availability of dopamine. Unfortunately that availability increases everywhere, not just in the areas that were lacking. So an increase of dopamine to the temporal lobes, for example, will cause auditory hallucinations, in others paranoia or violent reactions out of fear. Some Scandinavian countries had started an early intervention program by which teenagers showing the early signs of schizophrenia would be started on medications to prevent progression to the worst forms. Those patients had a better outcome than those who were not treated with antipsychotics. Here: easy reading