PERFORMANCE OF PATIENTS WITH SCHIZOPHRENIA ON A PEN AND PAPER VISUOSPATIAL WORKING-MEMORY TASK WITH SHORT DELAY

Human and nonhuman primate data suggest that visuospatial working memo ry is mediated by a neural network that includes the prefrontal cortex . Simple working memory tasks are less complex than standard neuropsyc hological tests of frontal dysfunction. As such, they are less vulnera ble to general performance factors such as amotivation and uncooperati veness in schizophrenic patients. These tasks thus hold promise as pot ential measures of frontal dysfunction in schizophrenia. However, the specific parameters of visuospatial working memory deficit in schizoph renia have not been established. This study assessed working memory fu nctions in 18 schizophrenic patients and 28 controls using a pen-and-p aper analogue of a monkey prefrontal cortex activation task. Schizophr enic patients and controls performed similarly on a sensory-guided tas k that did not require working memory functions, yet schizophrenic pat ients performed significantly worse than controls on tasks that requir ed subjects to retain visuospatial information for delay periods of 10 and 20 s. These data suggest that the working memory deficits in pati ents with schizophrenia begin to appear less than 10 s following encod ing of visuospatial information and that these working memory deficits can be assessed with easily administered pen-and-paper tasks. (C) 199 7 Elsevier Science B.V.