Are Socio-Affective Impairments in Ataxia Related to Language and Processing Speed Deficits?

International audienceOver the last decade a number of studies have demonstrated the implication of the cerebellum in cognition, including verbal memory, executive function, and language. Social cognition abilities like emotion attribution and theory of mind are essential in social interaction and rely on verbal abilities and executive functions. Involvement in social cognition has been explored in the most common forms of Spinocerebellar Ataxia (SCA), but several aspects remain unclear. The present study tested whether socio-affective impairments are observed in SCA patients by using different tasks and to determine whether these impairments were associated with reduced verbal processing and/or processing speed. 13 patients (SCA1, n=1; SC2, n=5; SCA3, n=7) were matched with 13 controls for gender, age and education. Verbal and non-verbal theory of mind abilities were tested (validated French versions of an attribution of intention test, faux-pas test), and emotion attribution. Language efficacy was explored in a word fluency test and processing speed in two non-motor tasks. Results revealed no difference between SCA2 and SCA3 patients in neither socio-affective nor cognitive test. Performance on all tests was on contrary significantly reduced in the SCA patient group compared to controls. SCA patients’ performance was positively correlated between the three social cognition tests, indicating a somewhat generalized impairment. Their performance rate in each of three social cognition tests was further correlated with processing speed but not with word fluency. In the verbal theory of mind task they displayed however comprehension deficits of the faux-pas and of general control questions. Taken together the data suggest that processing speed and comprehension difficulties might account, partly at least, for socio-affective and cognitive deficits in both genotypes. This conclusion was modulated by the observation that the neuropsychological features did not correspond well with age of illness diagnosis and illness duration, indicating that there is a degree of heterogeneity in the cognitive profiles and social cognitive impairments in SCA patients