Wisconsin Card Sorting Test as a Measure of Executive Function Impairments in Stroke Patients

The Wisconsin Card Sorting Test (WCST) is among the most frequently administered neuropsychological tests. It is assumed that successful completion of this test requires engagement of executive functions (EF). One of the most common origins of EF impairments is ischemic stroke. The present study intends to evaluate the diagnostic use of the WCST as a measure of these impairments in poststroke patients. Forty-four patients (8 women and 36 men) who had recent unilateral stroke (22 left hemisphere, 22 right hemisphere) participated in the study. The overall accuracy of the WCST in classifying stroke survivors as having executive disorders was poor. Nevertheless, statistical analysis revealed its negative predictive power to be greater than positive predictive power (i.e., normal scores on the WCST reliably indicated the absence of executive disorders in 8 or more out of 10). Performance on the WCST is clearly influenced by severity of the executive disorders. Namely, patients with severe impairment of EF (as measured by go/no-go, fluency, and other EF tests) performed more poorly on the WCST than patients with lesser impairment or those with no impairment at all, the latter group's results being indistinguishable. In addition, this study highlights a three-factor solution to the WCST, which accounted for 90.3% of the variance. The scores that most strongly loaded on Factors 1 to 3 were, in order: percentage of conceptual-level responses, number of trials to complete the first category, and failures to maintain the set of responses. Finally, an analysis using multivariate analysis of variance, with the anterior versus posterior site and left versus right side of the lesion as independent variables, revealed a relatively weak effect of lesion location on the WCST performance. In particular, with respect to all test scores, there is only one significant interaction between the site and side of lesion was obtained (F(1,24)=4.12; p.05; i.e., the number of categories achieved was significantly smaller after damage to the frontal lobe on the left than on the right side, whereas the laterality effect was not significant after nonfrontal lesions). In conclusion, to ascertain the cerebral substrates of poststroke executive dysfunction, there is a need to apply more accurate tests than the WCST. The study highlights the importance of a multicomponent approach to executive functioning in stroke patients.