Cerebellar cognitive affective syndrome and the neuropsychiatry of the cerebellum

Abstract

The traditional teaching that the cerebellum is purely a motor control device no longer appears to be valid, if indeed it ever was. Current evidence indicates that there is functional topographic organization in the cerebellum such that the cerebellar anterior lobe, adjacent part of lobule VI, and lobule VIII and their associated nuclei are principally engaged with motor control. In contrast, the great expanse of the cerebellar posterior lobe (lobules VI and VII) and associated nuclei are engaged in the modulation of supramodal, higher order functions. This connectional and functional arrangement manifests clinically in two overarching clinical syndromes. Lesions of the motor cerebellum result in the cerebellar motor syndrome of Ataxia, dysmetria, dysarthria, and oculomotor abnormalities. Lesions of the cognitive and limbic cerebellum lead to the cerebellar cognitive affective syndrome (CCAS), both in adults and in children, characterized by impairments in executive function, visual-spatial processing, linguistic deficits, and affective dysregulation. The affective component of the CCAS, conceptualized as the neuropsychiatry of the cerebellum, has been grouped according to five major domains: attentional control, emotional control, autism spectrum disorders, psychosis spectrum disorders, and social skill set. Within each of these domains, behaviors may reflect cognitive overshoot or undershoot, akin to the disorder of motor control seen in the cerebellar motor syndrome. This chapter focuses on the behavioral neurology and neuropsychiatry of the cerebellum in a number of different disease states, and draws attention to the fact that this rapidly evolving field of neuroscience has clinically relevant ramifications for adults, children, and infants with cerebellar dysfunction. This chapter aims to enhance the recognition of the CCAS and its theoretical underpinnings, and to highlight the promise these new insights hold for novel interventions in patients with neurobehavioral and psychiatric disease linked to the cerebellum.