Articulatory rehearsal in verbal working memory: a possible neurocognitive endophenotype that differentiates between schizophrenia and schizoaffective disorder

Working memory deficits represent candidate endophenotypes for major psychiatric disorders. The aim of the present study was to compare directly specific subcomponents of working memory in patients with schizophrenia and schizoaffective disorder as well as in healthy controls. Of each group, 11 subjects matched for gender, age and educational status underwent experimental neuropsychological testing of different components of working memory. In order to be able to attribute possible deficits to dysfunctions of underlying brain circuits we used the same Sternberg item-recognition tasks as in previous neuroimaging studies of working memory (1–4). In contrast to patients suffering from schizophrenia, schizoaffective patients did not differ significantly from healthy subjects in working memory task performance. Direct comparisons of the two patient groups revealed a specific working memory deficit of schizophrenic patients in the articulatory rehearsal task, although there was no significant difference in psychopathological rating scales between the two groups. This suggests that the functional integrity of the articulatory rehearsal mechanism may be a endophenotypic marker that differentiates between these two diagnostic groups.