Comparative effects of risperidone and olanzapine on cognition in elderly patients with schizophrenia or schizoaffective disorder

Abstract

Objective: To examine the effects of risperidone and olanzapine on cognitive functioning in elderly patients with schizophrenia or schizoaffective disorder.

Method: One hundred seventy-six elderly inpatients and outpatients with schizophrenia or schizoaffective disorder were enrolled in this multicenter, double-blind trial. After their antipsychotic medications were tapered for 1 week, patients were randomly assigned to receive either risperidone 1 to 3 mg/day or olanzapine 5 to 20 mg/day for 8 weeks. Performance on the Continuous Performance Test (CPT), Serial Verbal Learning Test (SVLT), TMT (Trail Making Test) Parts A and B, Wisconsin Card Sorting Test (WCST), and Verbal Fluency Examinations (VFE) was assessed at baseline and at end point.

Results: Patients in the risperidone group had improved scores on at least one test of attention, memory, executive function, and verbal fluency, and those in the olanzapine group had improved scores on at least one test of attention and memory function. Scores on the TMT Part B, WCST total errors (executive function domain), and the VFE improved significantly from baseline in the risperidone group but not in the olanzapine group. No significant differences in change scores between the two groups were found. Higher baseline scores on each test predicted more improvement at endpoint.

Conclusions: Low doses of risperidone and olanzapine improve cognitive function in elderly patients with schizophrenia or schizoaffective disorder. Consistent with research in younger populations, these improvements occur in aspects of cognitive functioning related to functional outcome.