Assessment of executive dysfunction during activities of daily living in schizophrenia

Many neuropsychological studies have described deficits of memory and executive functions in patients with schizophrenia, and the severity of these deficits seems to be determinant in predicting the community outcome of these patients [Schizophr. Bull. 26 (2000) 119]. However, neuropsychological evaluation does not provide valuable information about how the cognitive deficits directly affect daily living, that is, which cognitive deficit affects which behavior. The present study aimed at determining whether executive dysfunction in schizophrenia could be directly measured by analyzing three activities of daily living (ADL), in addition to assessing the ecological validity of commonly used neuropsychological tests. Within specific ADL (choosing a menu, shopping the ingredients, cooking a meal), the sequences of behaviors that have been performed by 27 control subjects and 27 patients with schizophrenia were both analyzed by using a preset optimal sequence of behavior. When compared with control subjects, patients with schizophrenia showed more omissions when choosing the menu, more sequencing and repetitions errors during the shopping task, and more planning, sequencing, repetition and omission errors during the cooking task. These behavioral errors correlated significantly with negative, but not with positive symptoms of the patients. Furthermore, they also correlated with the poor performances on executive neuropsychological tests, especially those sensitive to shifting and sequencing abilities, but not with memory tests. These results suggest that executive deficits in schizophrenia may specifically affect ADL and that such deficits can be quantitatively assessed with a behavioral scale of action sequences.