The Cerebellar Cognitive Affective Syndrome and the Neuropsychiatry of the Cerebellum

Abstract

Cognitive and limbic functions are represented in the cerebellar posterior lobe and vermis. Lesions of these areas produce dysmetria of thought, manifesting as the cerebellar cognitive affective syndrome (CCAS; Schmahmann’s syndrome). This is the counterpart to the cerebellar motor syndrome which results from lesions of the motor representation in the cerebellar anterior lobe and lobule VIII. The CCAS is characterized by impairments in executive function, visual spatial processing, linguistic deficits, and regulation of affect. The affective component of the CCAS, conceptualized as the neuropsychiatry of the cerebellum, is 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 and emphasizes the clinically relevant manifestations for adults and children with a wide range of cerebellar disorders. Recognition of the CCAS throughout the age spectrum is important for patient care, and it highlights the promise that new insights into cerebellar function hold for novel interventions in patients with neurobehavioral and psychiatric diseases linked to the cerebellum.