Antipsychotic polypharmacy and high doses have been associated with poor outcome and increased adverse effects in schizophrenia. However, their relation to cognition has been poorly studied.

40 right-handed patients (mean age: 42.87 years; SD:10.57) with DSM-IV schizophrenia, were recruited in an acute psychiatric ward. They were assessed on the Spatial Working Memory test (SWM) of the Cambridge Neuropsychological Test Automated Battery (CANTAB) and the Wechsler Adult Intelligence Scale (WAIS-III) at a time when they were able to cooperate with neuropsychological testing. The pattern of their pharmacological treatment was also assessed. Statistical correlation and Mann-Whitney tests were performed using the SPSS, as appropriate.

18 patients were receiving antipsychotic polypharmacy (≥2 antipsychotics) and 22 monotherapy. 13 patients received an excessive (≥1000 chloropromazine mEq(CmEq)/day), and 22 a normal antipsychotic dosage. No significant difference was detected on any of the SWM performance measures between the two groups of patients receiving either polypharmacy or monotherapy. These groups did not also differ in the WAIS full scale, performance or verbal IQ scores. When the patients were divided into two groups receiving either an excessive or a normal dose of antipsychotics, these two groups also showed a similar SWM and WAIS performance. The total antipsychotic dose showed negative but nonsignificant correlations with the SWM performance scores.

We did not detect any influence of antipsychotic polypharmacy or excessive dosing on spatial working memory in schizophrenia. This finding supports the independence of working memory deficits from the effects of treatment in schizophrenia.