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

Background and Objectives: Several studies have shown an improved performance on neuropsychological tests among patients treated with atypical antipsychotics compared to traditional ones. Here we present a meta-analysis of various randomised control 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 moderating 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 typical 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 differences in their quality, the dose of haloperidol, the duration of treatment, pharmaceutical industry support, or the atypical antipsychotic used (all p > 0.05). Conclusions: The 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 antipsychotics. Received 29 April 2008 Revised 29 January 2009 Accepted 5 February 2009 78 GEORGINA GUILERA ET AL.