Educational level and age influence spatial working memory and Wisconsin Card Sorting Test performance differently: a controlled study in schizophrenic patients.

The influence of educational level and age on executive function, as evaluated by the Wisconsin Card Sorting Test (WCST), and 'working memory,' as evaluated by means of a visual-manual delayed-response task, has been investigated in 25 schizophrenic patients and 35 healthy controls matched for age. Different patterns of correlations between educational level, age and cognitive variables were seen for the 'working memory' task but not for the WCST. No significant correlations between the WCST and the 'working memory' task indexes have been observed. Based on multivariate analyses, poor performance of schizophrenic patients on working memory and executive function tasks was observed; after covarying for the educational level, group differences were no longer significant for executive functions, but the difference in 'working memory' performance persisted. The implications of sociodemographic variables as well as the role of statistical manipulation are evaluated and their differential impact on 'working memory' and executive functions is proposed in further support of these neurocognitive constructs that may be dissociable.