Face emotions recognition in spinocerebellar ataxia patients

Objectives: Recognition of other’s emotional states is fundamental for a regular social behaviour. So far only few studies have assumed that cerebellum is also involved in the emotional processing. We know that cerebellum is implicated in cognitive functions with a peculiar pattern of impairment in patients with cerebellar lesions defined as Cerebellar Cognitive Affective Syndrome, including frontal, atten- tional, linguistic, visuospatial, mnestic, affective and social disturbance. Spinocerebellar ataxias (SCA) are a group of heterogeneous degen- erative pathologies involving cerebellum and his connections. Garrard et al. (2008) demonstrated that SCA patients are not impaired on tasks requiring emotional processing, but on Theory of Mind (ToM) tasks, suggesting that social cognition can be fractionated into functionally independent subsystems. In the present study we assessed the ability to identify facial expressions of emotions in a group of SCA patients to better under- stand the role of cerebellum in the emotional processes. Methods: Twenty patients, affected by SCA (9 SCA2, 5 SCA6, 2 SCA7, 4 SCA8), were recruited in our Ataxia Center. To assess recognition of facial emotions we used the Ekman 60 Faces Test for basic emotions, that used photographs displaying happiness, sadness, disgust, fear, surprise or anger. For social emotions we used the Tamietto 50-faces displaying flirtatiousness, admiration, arro- gance, guilt or neutral. Twenty healthy subjects age and education- matched were enrolled as a control group. Participants were required to choose the label that best describes the emotion displayed by each face. Results: We found an impairment in basic emotions recognition in patients, the worse performance was in sadness recognition. We did not find any differences between SCA’s subgroups. A greater impairment has been observed in the social emotions recognition. Negative emotions (arrogance, guilt) recognition was more affected and SCA2, SCA7 had the worse scores. Conclusion: The deficit in emotions recognition among SCA patients could be partially explained by their executive or attentional deficit linked to the cerebellar degeneration. The worse recognition in social emotions could be justified by their greater complexity and consequent heavier mental processing demand. The alternative hypothesis is that cerebellum is involved not only in ToM, but also in other aspects of the social cognition more focused on somatomotor processing.