DEFICITS IN MULTIPLE SYSTEMS OF WORKING-MEMORY IN SCHIZOPHRENIA

Working memory, the ability to hold and manipulate information 'on-lin e' in a temporary memory store, is impaired in schizophrenia. This imp airment may be characterized within the framework of two opposing theo retical models: (1) central executive as coordinator of component proc esses of working memory or (2) multiple independent systems of spatial and object memory. In order to test which of these models better expl ains the working memory deficit of schizophrenia, 14 schizophrenic pat ients and 12 age- and gender-matched control subjects performed tests of spatial memory (dot location), object memory (shapes, color dots) a nd a dual paradigm (dot location + shapes). If schizophrenia impairs t he central executive, a group-by-task interaction would demonstrate ex cessively worse performance on the dual than single tasks in schizophr enics relative to controls; however, the absence of an interaction wou ld be consistent with deficits in the multiple working memory systems. The schizophrenic group was significantly impaired on all measures, a nd both the schizophrenic and control performance was worse on the dua l than the single tasks. Despite the schizophrenic group performance d eficits on the single tasks, the extent of such deficit did not appear additive and contributive to the dual tasks. The lack of a group-by-t ask interaction provided no support for the central executive model of dysfunction. Rather, the results uphold the model of working memory d eficits arising from compromise of multiple (here spatial and object), relatively independent systems, both of which are affected in schizop hrenia. (C) 1997 Elsevier Science B.V.