Probabilistic classification and gambling in patients with schizophrenia receiving medication: comparison of risperidone, olanzapine, clozapine and typical antipsychotics.

RATIONALE: We have previously shown that patients with schizophrenia treated with typical antipsychotics were impaired on the weather prediction probabilistic classification learning (PCL) task that relies on striatal function, and that similar patients treated with atypical antipsychotics were impaired on the Iowa gambling task (IGT) that depends on medial prefrontocortical function.

OBJECTIVES

We tested the hypothesis that test performance of patients treated with risperidone will be more similar to those treated with typical rather than atypical antipsychotics.

RESULTS

Groups of schizophrenia patients treated with risperidone, olanzapine, clozapine or typical antipsychotics did not differ on the Positive and Negative Syndrome Scale or the Mini Mental State Exam (MMSE) but scored lower than controls on the MMSE. For the PCL task, patients treated with clozapine improved over trials while those treated with typical antipsychotics, olanzapine, or risperidone did not. For the IGT, patients treated with typical antipsychotics or risperidone improved over trials while those treated with clozapine or olanzapine did not.

CONCLUSIONS

Results generally supported the hypothesis that patients treated with risperidone perform more like those treated with typical antipsychotics than those treated with other atypical antipsychotics.