The comparative efficacy and long-term effect of clozapine treatment on neuropsychological test performance

Previous studies have suggested that clozapine may improve neuropsychological test performance. The current study was designed to examine the comparative efficacy and the long-term effect of clozapine (versus haloperidol), on neuropsychological test performance. Neuropsychological measures of executive/attention, visuospatial, and memory function were administered to schizophrenic patients at baseline, at the end of a 10-week double-blind study, and after 1 year of open clozapine treatment. Symptoms and function ratings were obtained at the same time points. The 10-week double-blind study revealed significant group-by-time interactions for two measures: Categorical Fluency and WAIS-R Block Design. At the end of 1 year of open treatment there were significant improvements in Verbal Fluency, Mooney Faces Closure, and WAIS-R Block Design performance, and trend improvements in Stroop Color-Word Interference, Category Fluency, and WMS-R Logical Memory performance. Improvements in neuropsychological performance were unrelated to symptom changes. Change in selected neuropsychological measures were significantly correlated with improvement in quality of life. The results suggest that long-term clozapine treatment may have beneficial effects on a broad range of cognitive functions.