Executive functioning in schizophrenic and bipolar disorder
The purpose of this study was to utilize the Wisconsin Card Sorting Test (WCST) to expand upon findings of executive dysfunction in schizophrenia and to compare schizophrenic performance to that of manics, given similarities in psychiatric symptomatology. It was hypothesized that both schizophrenic and bipolar patients would show deficient levels of executive functioning in comparison to normative data, and the schizophrenic group would show greater impairment than the bipolar group. It also was hypothesized that negative symptoms would be associated with poorer performance on the WCST, and higher estimated intellectual levels (IQ) would be associated with better achievement on measures of executive functioning. Fifteen in-patient schizophrenic and fifteen in-patient bipolar disorder, manic patients who were stabilized on medication were assessed with the WCST, measures of intellectual functioning (WAIS-R estimated IQ and WRAT-III), and symptom level ratings (PANSS). The performance of schizophrenic patients did not differ from WCST normative data for the number of categories achieved and maintaining the sorting set. The schizophrenic patients did make a greater percent of perseverative errors and responses than the normative sample. Manic patients performed more poorly than WCST normative sample for the number of categories achieved, perseverative errors, and perseverative responses. However, the performance of bipolar patients was comparable to normative data in terms of maintaining the sorting set. No significant differences were found between the two patient groups. Negative symptoms were not found to be related to any of the executive function measures examined. A relationship between intellectual level and WCST performance was found only for bipolar subject, such that those with higher intellectual functioning completed a greater number of WCST categories and made fewer perseverative errors and responses. Thus, certain manic patients showed as much, or more, difficulty with executive functions as schizophrenic patients. However, both patient groups were able to hold on to the sorting principle though they perseverated when the demands of the task changed. Further research needs to clarify the relationship between executive functions and intellectual level. A low number of subjects participating limits the confidence in the results.
Stewart, Anna Marie, "Executive functioning in schizophrenic and bipolar disorder" (1997). ETD Collection for Fordham University. AAI9730108.