Any thoughts ? Found this study: 
The Effects of Clozapine, Risperidone, and Olanzapine on Cognitive Function in Schizophrenia
These studies provide (1) strong evidence that clozapine Improves attention and-verbal-fluency and (2) moderate evidence that clozapine improves some types of executive function. However, results of
the effects of clozapine on working memory and secondary verbal and spatial memory were inconclusive.
Risperidone has relatively consistent positive effects on working memory, executive functioning, and attention, whereas improvement in verbal learning and memory was inconsistent Preliminary evidence presented here suggests that olanzapine improves verbal learning and memory, verbal fluency, and executive function, but not attention, working memory, or visual learning and memory.