Improved detection of differential information-processing speed deficits between two disease-course types of multiple sclerosis.

Patients with multiple sclerosis (MS) frequently demonstrate impairments of information-processing speed (IPS) on measures such as the Paced Auditory Serial Addition Test (PASAT; D. M. A. Gronwall, 1977). The authors have previously shown that their new PASAT scoring method (mean dyad score) is better correlated in comparison with more traditional PASAT scoring method(s), with magnetic resonance imaging measurement of the total area (mm2) of white-matter sclerotic lesions (P. J. Snyder & J. C. Cappelleri, 2001). The present study reports that the mean dyad score discriminated 20 relapsing-remitting MS (RRMS) patients from 15 secondary-progressive MS (SPMS) patients noticeably better than did the standard scoring method(s). Mean dyad scores < 4.13 classified patients as having SPMS with 73% accuracy (sensitivity), whereas scores > or = 4.13 classified patients as having RRMS with 80% accuracy (specificity).