Cognitive outcomes received relatively little attention in the pivotal studies of MS disease modifying therapies (DMT), but some data suggest that DMT may have a positive impact on cognition. Gilenya is of special interest because it was found to have a significant protective effect on whole brain atrophy when compared against placebo and intramuscular interferon β-1a in two phase III studies, showing a 31-35% reduction in percentage brain volume change. Gilenya's effect on whole brain atrophy leads to the natural hypothesis that it may have a beneficial effect on cognitive function in MS. Also of particular interest is the extent to which protection of the thalamus and cortex contributes to Gilenya's effect on whole brain atrophy and possible effects on cognition.