The vast majority of schizophrenic patients demonstrates poor performance in different aspects of cognitive processing. Some of these cognitive deficits clearly have been identified as rate-limiting factors in social functioning. Over the past years, a series of meta-analyses has summarized the evidence for the benefits of cognitive remediation approaches. However, there are marked discrepancies between their findings.

The present contribution aims to provide a conclusive survey of the available evidence for the efficacy of cognitive remediation as derived from these meta-analyses and the findings of an own recent meta-analysis of all randomized controlled trials published in peer-reviewed journals.

Relevant meta-analyses and randomized controlled trials were identified by searching several electronic data bases and by hand-searching of reference lists. In order to compare the findings of the existing meta-analyses the reported effect sizes were transformed into a standardized effect size measure. For the own meta-analysis weighted mean effect size differences between comparison groups regarding various types of outcome were estimated. Their significance was tested by confidence intervals and heterogeneity tests were applied to examine the consistency of the effects.

The findings of systematic reviews covering cognitive remediation approaches differ considerably depending on the methodological rigor of included studies and the cognitive function targeted. The present meta-analysis provides support for small to medium improvements in attention, executive functioning and social cognition tasks, indicates small reductions in negative symptoms and a moderate transfer effect on social functioning. However, the durability of the effects remains unclear since follow-up data are missing.