Cognitive but Not Affective Theory of Mind Deficits in Progressive MS

Social cognitive deficits are an important consequence of multiple sclerosis (MS), yet our understanding of how these deficits manifest in progressive MS is currently limited. To this end, we examined theory of mind (ToM) ability in a sample of individuals with progressive MS using an ecologically valid virtual assessment tool that allows for delineation of cognitive ToM (inferring thoughts and intentions of others) from affective ToM (inferring emotions of others). We compared 15 individuals with progressive MS and 15 healthy controls on their ToM ability using the Virtual Assessment of Mentalising Ability. We found that, relative to healthy controls, participants with progressive MS were impaired in cognitive ToM, but not in affective ToM. Furthermore, we found that the MS participants' deficits in cognitive ToM were mediated by their general cognitive ability such that poor cognitive ToM ability in MS was explained by poor performance on tests of memory and processing speed. Our findings demonstrate that ToM deficits in progressive MS may be limited to cognitive ToM, while affective ToM is conserved. This could be attributable to the MS-related deficits in general cognitive ability, which appear to negatively affect only the cognitive component of ToM.