Quality of life in multiple sclerosis: does information-processing speed have an independent effect?

Information-processing speed (IPS) has been identified as an area of primary deficit in multiple sclerosis regardless of disease course. This study examines the extent to which information-processing speed contributes to quality of life (measured by the SF-36) in individuals with Multiple Sclerosis (MS), independent of level of neurological disability (measured by the Expanded Disability Status Scale (EDSS)). Fifty-two individuals with MS (29 relapsing-remitting and 23 primary-progressive) completed the SF-36 and neuropsychological measures related to speed of processing and were assessed using the EDSS. The EDSS was significantly related to all SF-36 scales except those measuring Mental Health and Role Limits--Emotional. While the EDSS contributed significantly to prediction of SF-36 component scores, addition of measures of IPS to the regression equation did not significantly improve prediction. It was noted, however, the effect size associated with addition of IPS scores were large, indicating that quality of life is indeed related to measures of IPS.