Information processing efficiency in patients with multiple sclerosis

Reduced information processing efficiency, consequent to impaired neural tr ansmission, has been proposed as underlying various cognitive problems in p atients with Multiple Sclerosis (MS). This study employed two measures deve loped from experimental psychology that control for the potential confound of perceptual-motor abnormalities (Salthouse, Babcock, & Shaw, 1991; Sternb erg, 1966, 1969) to assess the speed of information processing and working memory capacity in patients with mild to moderate MS. Although patients had significantly more cognitive complaints than neurologically intact matched controls, their performance on standard tests of immediate memory span did not differ from control participants and their word list learning was with in normal limits. On the experimental measures, both relapsing-remitting an d secondary-progressive patients exhibited significantly slowed information processing speed relative to controls. However, only the secondary-progres sive patients had an additional decrement in working memory capacity. Depre ssion, fatigue, or neurologic disability did not account for performance di fferences on these measures. While speed of information processing may be s lowed early in the disease process, deficits in working memory capacity may appear only as there is progression of MS. It is these latter deficits, ho wever, that may underlie the impairment of new learning that patients with MS demonstrate.