Wechsler Adult Intelligence Scale–Fourth Edition performance in relapsing–remitting multiple sclerosis

Abstract

Forty patients with relapsing–remitting multiple sclerosis (MS) completed the 10 core Wechsler Adult Intelligence Scale–Fourth Edition (WAIS–IV) subtests. Means for age and education were 42.05 years (SD = 9.94) and 14.33 years (SD = 2.40). For all participants, the native language was English. The mean duration of MS diagnosis was 8.17 years (SD = 7.75), and the mean Expanded Disability Status Scale (EDSS; Kurtzke, 1983) score was 3.73 (SD = 1.41) with a range from 2.0 to 6.5. A control group of healthy individuals with similar demographic characteristics also completed the WAIS–IV and were provided by the test publisher. Compared to controls, patients with MS earned significantly lower subtest and composite scores. The patients' mean scores were consistently in the low-average to average range, and the patterns of performance across groups did not differ significantly, although there was a trend towards higher scores on the Verbal Comprehension Index (VCI) and lower scores on the Processing Speed Index (PSI). Approximately 78% of patients had actual Full Scale IQs that were significantly lower than preillness, demographically based IQ estimates.