Theory of mind in multiple sclerosis: A neuropsychological and MRI study

Social cognition stands among the most frequently affected yet the least studied cognitive domains in multiple sclerosis (MS). Theory of mind (ToM) is a social cognitive facet that implies the one's ability to predict others' mental states. The objective of this study was to assess the relationship between ToM and neuropsychological and neuroimaging data.

Thirty-eight consecutive MS patients completed the Reading the Mind in the Eyes test (RMET). They underwent a neuropsychological evaluation and a 3T T1-weighted brain MRI. A fully automated volume-based morphometry algorithm (MorphoBox) was applied to calculate regional brain volumes. Correlation analysis was performed using Spearman's test.

Among the sociodemographic and clinical data, significant correlations were found between RMET scores and each of years of education (r=0.54; p<0.01) and the duration of the disease progressive phase (r=-0.46; p<0.01). Regarding neuropsychological measures, RMET scores were directly correlated with information processing speed (r=0.58; p<0.01) and empathy (r=0.46; p<0.01) scores. As for brain volumes, RMET scores were directly correlated with parietal (left: r=0.39; right: r=0.46; p<0.05) and temporal (left: r=0.36; right: r=0.40; p<0.05) white matter volumes, as well as with cingulate (left: r=0.32; right: r=0.44; p<0.05) gray matter volumes.

These results highlight the relationship between ToM and some of the disease characteristics and cognitive domains. Importantly, ToM performance in MS is associated with brain volumes of key areas in social cognitive networks. Further works are needed to enhance the current knowledge on the underlying mechanisms of ToM deficits in this population.