Comparability of the WCST and WCST-64 in the assessment of first-episode psychosis.

The Wisconsin Card Sorting Test (WCST) was designed as a measure of executive functioning and is commonly used in the assessment of psychiatric disorders. The original WCST, consisting of 128 cards, has been criticized as being too lengthy for patients experiencing significant distress. Consequently, a shortened version consisting of a single 64-card deck (WCST-64) was created. The purpose of this study was to examine the comparability of the WCST and WCST-64 in 99 patients with first-episode psychosis. Findings showed the WCST-64 yielded a mean T score for perseverative responses (PR) that was 4.08 points lower than the corresponding variable from the WCST, and the correlation between the variables was r = .65. The mean discrepancy was only 2.34 for nonperseverative error (NPE) T scores and the correlation was also stronger, r = .82. Nearly half the sample (44%) had a T score discrepancy between the respective PR indexes that was greater than 1 SD, whereas this discrepancy was observed in only 4% of the sample for NPE. Based on a cut point of < 40T to define impaired versus normal performance for PR, 80% of the sample received the same classification. These findings suggest that NPE scores may be comparable across both tests. Conversely, whereas the PR score from the WCST-64 and WCST can be used as a gross measure of impairment, this score should not be used interchangeably to characterize the severity of perseverative tendencies in first-episode patients on a case-by-case basis. (PsycINFO Database Record (c) 2019 APA, all rights reserved).