Concurrent Validity of the PASAT and Adjusting-PSAT in Patients with Multiple Sclerosis

Impaired information processing speed (IPS) is common in multiple sclerosis (MS). Performance on the Paced Auditory Serial Addition Test (PSAT)—the measure recommended by the United States National MS Society Task Force to track changes in IPS—does not indicate the precise speed at which IPS breaks down. A newer version of the task, the Adjusted Paced Serial Addition Test (A-PSAT), provides such an index. This study examined the relationship between PASAT and A-PSAT performance in a sample of 52 individuals with MS. Those with relapsing-remitting MS (RRMS) were significantly younger and had significantly lower EDSS scores than those with chronic progressive MS (CPMS). Though performance indicators for both the PASAT and A-PSAT were better for patients with RRMS, differences in performance between MS groups were not significant (P >.05). Results of comparisons between the A-PSAT and PASAT support concurrent validity of the A-PSAT. In addition, performance on the APSAT—but not the PASAT—was significantly related to functional status as measured by the EDSS. Although these findings need to be replicated, they indicate that the A-PSAT may be a viable alternative to the existing PASAT.