The relationship between symptomatic remission and neuropsychological improvement in schizophrenia patients switched to treatment with ziprasidone

Background: A definition of clinical remission in schizophrenia has recently been proposed. However, it is also known that neuropsychological (NP) impairments may be better predictors of functional outcomes than clinical symptoms. Understanding the relationship between clinical remission and cognitive improvement may be required in order to predict functional improvements, so we examined the development and convergence of clinical remission and neuropsychological improvements in a sample of patients with schizophrenia whose medication was switched to ziprasidone. Methods: One hundred eighty-four patients were switched from their previous treatment with risperidone, olanzapine, or conventional antipsychotics to open-label ziprasidone treatment. One hundred and thirty seven patients were not in remission at baseline and 40 met the clinical criteria for remission at study entry. We rated their symptoms with the PANSS at baseline and after 6 months of treatment. We performed an NP assessment and generated a composite score which was examined for improvements. Results: Of the 184 cases, 48 (26.1% of the total sample) met the remission criteria at baseline. Of these cases, 41 (85%) sustained their remission at the 6-month follow-up. Of the remaining 136 cases, 33% developed remission by the 6-month follow-up. Thus, a total of 55% of the total sample were in remission at the 6-month endpoint. A comparable number of the patients, 34%, improved by 0.5 SD or more in their cognitive performance. Baseline NP performance was not associated with remission at baseline and did not predict achieving remission over time. Further, clinical remission was not correlated with concurrent NP improvements. However, 33 patients achieved clinical remission and improved by 0.5 SD in their NP performance. Implications: After a switch from previous treatment to open-label ziprasidone more than half of patients with schizophrenia experienced sustained clinical remission over 6 months and 32% of the patients achieving remission experienced a concurrent NP improvement. Later research will be required to determine which aspects of improvement (clinical remission and/or cognitive improvements) are required for functional improvements.