haloperidol versus risperidone: a comparison of beneficial effect on cognitive function of patients with chronic schizophrenia

objective: the current study was performed to evaluate the cognitive improvements of the chronic schizophrenic patients treated with risperidone in comparison with those treated with haloperidol according to wisconsin card sorting test (wcst). methods: in a double blind clinical trial, 65 patients with a diagnosis of chronic schizophrenia were randomly allocated into two groups. they received a 7 days washout and then during an eight weeks period one group was treated with risperidone 4-8 mg daily while patients in the other group received haloperidol 10-15 mg daily. patients of the two groups were assessed by positive and negative syndrome scale (panss) and brief psychiatric rating scale (bprs). patients’ cognitive abilities were assessed by wcst. treatment side effects were also evaluated in both groups. results: the overall panss score, the scores of the positive and negative subscales and bprs scores revealed that risperidone was significantly superior to haloperidol in the treatment of psychotic symptoms (p<0.001). risperidone caused less marked dyskinetic side effects in comparison with halopridol (p<0.001). haloperidol produced more symptoms of parkinsonism and tardive dykinesa than risperidone. the positive cognitive effect of risperidone was significantly better than haloperidol at 4th (p<0.001) and 8th (p<0.001) weeks. conclusion: apart from being more effective in improving positive and negative symptoms of psychotic disorders, risperidone is also more beneficial in reducing the symptoms of cognitive impairment in chronic and long standing form of schizophrenia. it also seems to be better tolerated than haloperidol.