Did I say that word or did you? Executive dysfunctions in schizophrenic patients affect memory efficiency, but not source attributions

Abstract

Introduction. Schizophrenic patients have difficulties in recognising previously presented verbal information and identifying its sources. The antecedents of these recognition and source misattributions are, however, largely unknown. The current study examined to what extent schizophrenic patients’ lack of memory efficiency, their memory errors, and their source misattributions are related to neurocognitive deficits (i.e., executive dysfunctions). Methods. 23 schizophrenic patients and 20 healthy controls were administered an adapted version of the Deese/Roediger-McDermott (DRM) task from which parameters of memory efficiency, memory errors, source misattributions, and two-high threshold measures were derived. Furthermore, two neurocognitive tasks tapping executive functions were administered: the Wisconsin Card Sorting Test (WCST) and the Behavioural Assessment of the Dysexecutive Syndrome (BADS). Using multiple linear regression analyses, we examined whether these neurocognitive measures predicted various memory parameters. Results. Patients with schizophrenia showed poorer memory efficiency and were more prone to make internal-external source misattributions with high confidence. However, they did not more often falsely recognise critical lure words than controls. Executive dysfunctions predicted memory efficiency, but not source misattribution performance. Conclusion. Our findings provide further evidence that schizophrenic patients’ memory impairments are intimately related to fundamental neurocognitive deficits.