Validity of the Wisconsin Card Sorting and Delis-Kaplan Executive Function System (DKEFS) Sorting Tests in multiple sclerosis

Multiple sclerosis (MS) is a disease of the central nervous system that causes cognitive impairment with a frequency of roughly 50%. While processing speed and memory defects are most commonly observed, a substantial number of patients also have deficiency in higher executive ability. Two tests, the Wisconsin Card Sorting Test (WCST) and the Sorting Test from the Delis-Kaplan Executive Function System (DKEFS), have been recommended for evaluation of neuropsychological impairment in MS. We investigated the validity of these tests in 111 MS patients and 46 age- and education-matched controls. MS patients performed more poorly on both measures, but only the DKEFS discriminated the groups after controlling for depression. Both tests were modestly or strongly correlated with MRI indices of brain atrophy or lesion burden and discriminated between employed and disabled patients. While both tests appear to have good validity in the MS population, the availability of alternative forms makes the DKEFS an attractive alternative to the WCST, as was suggested by a consensus panel.