Differences in performance and learning proficiency on the Wisconsin Card Sorting Test in schizophrenia: do they reflect distinct neurocognitive subtypes with distinct functional profiles?
The aim of this study was two-fold: 1) to determine whether a priori subtyping of patients with schizophrenia based on both overall performance on a measure of executive-function, the Wisconsin Card Sorting Test (WCST), and ability to learn the task with expanded instruction, could be confirmed with other, independent measures of executive-function and learning, and, if so, 2) to determine whether these groups have different neurocognitive profiles and show differences in functional capacity. Fifty-four outpatients with schizophrenia were divided by WCST performance into three groups: intact executive-function (n=28), "good learner" (n=13), and "poor learner" (n=13) groups. These groups were then assessed with a comprehensive neurocognitive test battery and a performance-based measure of functional status, the UCSD Performance-based Skills Assessment (UPSA). The WCST-intact subgroup performed significantly better than other groups on a second measure of executive-function and in working memory, and speeded motor sequencing. Impaired WCST patients who benefited from expanded WCST instruction ("good learners") also showed better performance than patients who did not benefit from instruction ("poor-learners") on a second measure of learning, as well as on a measure of auditory divided attention. The intact WCST subgroup had greater functional capacity than either "strong" or "poor" learners. These subtypes may have implications for response to behavioral treatment interventions.