Cognitive and brain reserve in multiple sclerosis--A cross-sectional study.

Background: Cognitive impairment (CI) is detected in 40-70% of multiple sclerosis (MS) patients, but only 33-50% of the CI variance is explained by the disease burden assessed by MRI. The cognitive reserve (CR) hypothesis has been postulated to account for this discrepancy. So far, most previous studies have confirmed the CR hypothesis in MS but failed to examine CR indices collectively or use clinically relevant neuropsychological assessments.