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Clinical utility of the Wisconsin Card Sorting Test: Evidence for a cross-diagnostic continuum of prefrontal dysfunction in community-based schizophrenic and bipolar disordered subjects

16 December 1988


A study was conducted for the purpose of bringing together the theoretical and clinical utility of the Wisconsin Card Sorting Test (WCST) through a partial' replication of a treatment from a prior study and examination of differences between results previously obtained for a hospitalized schizophrenic sample with those of a less functionally ill sample and extended to include another diagnostic category of major mental illness. Samples of 24 schizophrenic and 24 bipolar chronic mentally ill clients of a community-based treatment program were administered the WCST. Those in the treatment condition were taught the abstract reasoning task using increasing increments of instruction to the level of card-by-card instruction, at which point instruction was withdrawn. Results show the training is effective in increasing performance to above normal levels but that subjects are unable to maintain the learning when training is withdrawn, with performance returning to baseline deficit levels. Overall results were as predicted in that, while the less functionally ill subjects have similar difficulty maintaining learning, they are able' to show some greater learning at earlier stages of training and to perform at a generally higher but still a deficit level. Their task performance difficulties are those of abstract reasoning, cognitive adaptability and maintenance of learning, functions associated with the dorsolateral prefrontal cortex and with behaviors of self-regulation and independent adaptive coping. It is suggested that, compared with performance of hospitalized subjects, the differences in their ability to handle the task are reflected in their generally stable functioning in a less restrictive treatment setting but one which provides considerable case management support. Notably, there were no significant differences in the level of performance of schizophrenic and bipolar subjects. The results are identified as contributing to mounting evidence associating WCST scores as particularly useful in identifying specific frontal lobe dysfunction associated with adaptive coping and self-regulation deficits, that are related to neuropsychological dysfunction consistent with conceptualizations of hypofrontality in the context of a "psychotic continuum" associated with the major mental illnesses of schizophrenia and bipolar affective disorder. As such, the test has considerable clinical diagnostic and prognostic utility for understanding and planning for community-based treatment of these disorders beyond that afforded by descriptive diagnoses alone.


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