Amphetamine improves cognitive function in medicated individuals with schizophrenia and in healthy volunteers

Background: Recent research on schizophrenia indicates that cognitive deficits in this illness are important predictors of functional outcome, highlighting the need for treatments that have a positive impact on cognitive function. Here we explore the hypothesis that acute administration of D-amphetamine can improve cognitive function in individuals with schizophrenia who are well-treated with typical antipsychotics, as well as in healthy controls performing under dual task conditions designed to elicit performance deficits analogous to those found in schizophrenia. Methods: Ten individuals with schizophrenia taking haldol or prolixin and 22 healthy controls performed spatial working memory, language production, and Stroop tasks under both placebo and 0.25 mg/kg of D-amphetamine. Results: D-Amphetamine improved reactions times on the spatial working memory and Stroop tasks for both individuals with schizophrenia and controls, and improved working memory accuracy in schizophrenia. In addition, D-amphetamine improved language production for both individuals with schizophrenia and controls. Conclusions: These results provide support for the hypothesis that the adjunctive administration of dopamine agonist can improve cognitive in individuals with schizophrenia taking typical antipsychotics. The results are discussed in terms of their implications for understanding the nature of working memory deficits in schizophrenia, and potential future avenues for cognitive enhancement in this illness. (c) 2005 Elsevier B.V. All rights reserved.