Cognitive improvement in schizophrenia with novel antipsychotic medications

The syndrome of schizophrenia often includes negative symptoms and severe cognitive deficits that are resistant to change with conventional pharmacotherapy. The efficacy of clozapine in the reduction of the negative syndrome has prompted a series of studies implicating circumscribed cognitive improvements. Restrictions on the use of clozapine have encouraged the development and introduction of novel compounds with a clinical efficacy profile similar to clozapine that are hoped also to have beneficial cognitive effects. The present review summarizes studies of the cognitive efficacy of novel antipsychotic medications, particularly in regard to issues in experiment design and study implementation that might facilitate additional research. Although preliminary support exists for relatively circumscribed improvement of cognitive status with the use of clozapine and risperidone-and more general improvement with the use of olanzapine-specific inferences relating cognitive change to particular treatments will remain speculative until more sophisticated investigations are completed. The present review emphasises the most relevant design limitations in past studies to provide practical suggestions for the implementation of subsequent investigations. Previous results have established the possibility of a medication-based change in cognitive status in schizophrenia. Future research will determine the validity of these changes, the cerebral mechanism involved, and their significance to improved prognosis. (C) 1999 Elsevier Science B.V. All rights reserved.