Background Multiple sclerosis (MS) is an inflammatory and neurodegenerative disorder of the CNS that is frequently associated with neuropsychiatric symptoms and decreased quality of life. Social support, which has been found to buffer the psychosocial burden of MS, critically depends on intact social cognition. Here we assess social cognition in patients with MS using a naturalistic video based test and explore if potential deficits in theory of mind (ToM) occur independently of known MS associated neuropsychiatric symptoms, such as depression and cognitive impairment.

Methods 45 outpatients with clinically definite MS and 45 age, sex and education matched healthy control subjects (HCs) underwent standardised testing using the Movie for the Assessment of Social Cognition. MS patients also completed a neuropsychological battery.

Results MS patients showed significantly impaired ToM compared with HCs. Impairments were more pronounced in identification of emotions than in identification of thoughts or intentions. Significantly lower ToM compared with HCs was detected in MS patients during the early disease stages, with limited disability and without substantial neuropsychological deficits.

Conclusions These results suggest impaired social cognition in MS. Importantly, ToM impairments in this group may not simply be a consequence of the well known neuropsychological deficits. Difficulties with correctly identifying emotions, thoughts and intentions in social situations may result in interpersonal problems and could contribute to the psychosocial burden of MS.