Both ziprasidone and olanzapine significantly improve cognitive functioning in patients with schizophrenia or schizoaffective disorder. However, the effect of ziprasidone is greater than that of olanzapine. The effects of a 6-month treatment are twice that of a 6-week treatment.

Two-stage study: (1) a 6-week study in a group of patients who were hospitalised with a diagnosis of schizophrenia or schizoaffective disorder, (2) patients who responded to treatment (37 taking ziprasidone and 54 olanzapine) were entered into a 6-month multicentre cathamnestic study; they continued treatment (ziprasidone at doses: 40, 60 or 80mg twice daily, olanzapine 5, 10 or 15mg daily)