Prolonged response times characterize cognitive performance in multiple sclerosis

Cognitive impairment is amongst the main symptoms affecting multiple sclerosis (MS) and should be comprehensively and accurately assessed. To study the added value of a computerized neuropsychological battery enabling the measurement of response times in the cognitive domains, 58 randomly selected MS patients and 71 age-, gender- and education-matched healthy subjects were evaluated. Construct and discriminant validity were assessed for the standard Neuropsychological Screening Battery for Multiple Sclerosis (NSBMS) and the Mindstreams (R) Computerized Cognitive Battery (MCCB). The MCCB demonstrated good construct validity in comparison with the NSBMS in memory (P < 0.001), executive function (P < 0.001), attention (P < 0.05) and information processing (P < 0.05) domains. In addition, it showed high discriminant validity most prominently for executive function, attention and motor skills (P < 0.001). Response times measured by the computerized battery were longer in all cognitive domains and varied with cognitive load, demonstrating that response time deficits in MS are associated with particular task demands. We conclude that in MS prolonged response times on a range of cognitive tasks signify abnormal conduction within demyelinative tracts.