Emotion attribution (EA) from faces is key to social cognition, and deficits in perception of emotions from faces underlie neuropsychiatric disorders in which cerebellar pathology is reported. Here, we test the hypothesis that the cerebellum contributes to social cognition through EA from faces. We examined 57 patients with cerebellar disorders and 57 healthy controls. Thirty-one patients had complex cerebrocerebellar disease (complex cerebrocerebellar disease group (CD)); 26 had disease isolated to cerebellum (isolated cerebellar disease group (ID)). EA was measured with the Reading the Mind in the Eyes test (RMET), and informants were administered a novel questionnaire, the Cerebellar Neuropsychiatric Rating Scale (CNRS). EA was impaired in all patients (CD p < 0.001, ID p < 0.001). When analyzed for valence categories, both CD and ID missed more positive and negative stimuli. Positive targets produced the highest deficit (CD p < 0.001, ID p = 0.004). EA impairments correlated with CNRS measures of deficient social skills (p < 0.05) and autism spectrum behaviors (p < 0.005). Patients had difficulties with emotion regulation (CD p < 0.001, ID p < 0.001), autism spectrum behaviors (CD p < 0.049, ID p < 0.001), and psychosis spectrum symptoms (CD p < 0.021, ID p < 0.002). ID informants endorsed deficient social skills (CD p < 0.746, ID p < 0.003) and impaired attention regulation (CD p < 0.144, ID p < 0.001). Within the psychosis spectrum domain, CD patients were worse than controls for lack of empathy (CD p = 0.05; ID p = 0.49). Thus, patients with cerebellar damage were impaired on an EA task associated with deficient social skills and autism spectrum behaviors and experienced psychosocial difficulties on the CNRS. This has relevance for ataxias, the cerebellar cognitive affective/Schmahmann syndrome, and neuropsychiatric disorders with cerebellar pathology.
Keywords: Cerebellar cognitive affective syndrome; Cerebellum; Dysmetria of thought; Emotion attribution; Social cognition; Social perception.