Effects of lurasidone on executive function in common marmosets.

Cognitive impairment is one of the major symptoms of schizophrenia, and is considered largely due to dysfunctions in the prefrontal cortex (PFC). Lurasidone, a novel atypical antipsychotic agent with high binding affinity for dopamine D2, serotonin 5-HT7, 5-HT2A and 5-HT1A receptors has been reported to have superior efficacy in rodents' models of cognitive impairment. However, the beneficial effect of lurasidone on cognitive impairment has not been evaluated in non-human primates. In this study, we investigated the effect of lurasidone on executive function, which is one of the cognitive domains, in common marmosets and compared the results to those of other antipsychotics. The effects of lurasidone, haloperidol, olanzapine, risperidone, quetiapine and clozapine on executive function were evaluated in naïve marmosets using the object retrieval with detours (ORD) task. Before drug treatment, marmosets' success rates in the easy trial of the test were almost 90%. However, maximum success in the difficult trial of the task reached only 50% after 8 days of training. Haloperidol, olanzapine and risperidone decreased correct performance even in the easy trial of the task. All drugs, except lurasidone, impaired success rate in the difficult trial. On the other hand, lurasidone dose-dependently increased marmosets' success rates in the difficult trial with significant effect at 10mg/kg. In conclusion, we have shown in this study that lurasidone, unlike conventional antipsychotics, improves cognition associated with executive function in common marmosets. These findings suggest that lurasidone would be more useful for treatment of schizophrenia cognitive impairment than other antipsychotics.