Background: Newer antipsychotic medications have been reported to enhance cognitive functioning in schizophrenia. Head to head studies with double-blind methods are still relatively few in number.
Objectives: To compare the relative cognitive enhancing effects of ziprasidone and olanzapine in the treatment of acutely ill inpatients with schizophrenia or schizoaffective disorder.
Procedures: In this 6-week, multicenter, double-blind, parallel-designed trial, patients were randomized to ziprasidone or olanzapine. No patient who had ever received a complete treatment trial with either of these medications previously was entered into the study. Cognitive testing measuring attention, motor speed, memory, executive functioning, and verbal skills were performed on all patients at baseline and endpoint.
Results: Treatment with either ziprasidone or olanzapine was associated with statistically significant improvements from baseline in attention, memory, working memory, motor speed, and executive functions. Treatment with olanzapine was also associated with a statistically significant improvement in verbal fluency. No statistically significant differences between these medications were found in the magnitude of improvement from baseline on any of the cognitive measures (other than verbal fluency in an exploratory analysis). Observed changes were not associated with changes in clinical symptoms measured using the PANSS or changes in movement disorders.
Conclusions: During 6 weeks of treatment, ziprasidone and olanzapine demonstrated substantial and comparable cognitive-enhancing effects relative to previous treatment. These effects were noted in all aspects of cognitive functioning previously proven to predict functional outcome in schizophrenia. No overall differences were detected between the medications in terms of the extent of cognitive enhancement.