Antipsychotic effects on cognition in schizophrenia: A meta-analysis of randomised controlled trials

Background and Objectives :S everal studies have shown an improved per- formance on neuropsychological tests among patients treated with atypical antipsychotics compared to traditional ones. Here we present a meta-analysis of various randomised con- trol trials with the aim of exploring whether patients treated with atypical agents obtain better results than those treated with traditional ones. Methods: The studies to be included were located electronically in November 2008 via the Medline database. A systematic review and a meta-analysis were undertaken; effect sizes were combined according to the random effects model. The effects of several mod- erating variables were evaluated. Results: The results, based on 18 independent studies (N = 1808), indicate that in terms of the global cognitive index atypical antipsychotics offer minor benefits compared to typ- ical agents as regards the cognitive function of patients, the mean effect size being 0.17 (95% CI 0.04 - 0.29). This observed effect was similar across the studies despite differ- ences in their quality, the dose of haloperidol, the duration of treatment, pharmaceutical industry support, or the atypical antipsychotic used (all p > 0.05). Conclusions :T he results suggest that compared to typical antipsychotics, atypical drugs produce a slight improvement in the global cognitive index, and several cognitive domains show a slight improvement in the neuropsychological performance of patients. We encourage further research on the relative effectiveness of several atypical antipsy- chotics.