THE CEREBELLAR COGNITIVE AFFECTIVE SYNDROME AND THE DYSMETRIA OF THOUGHT THEORY: CLINICAL RELEVANCE FOR THE DEVELOPING BRAIN

The cerebellum appears to be involved not only in the coordination of movement, but also in a number of functions that fall within the realms of cognition and emotion. This assertion is supported by anatomical and functional imaging studies, and behavioral observations in animals. The cerebellar cognitive affective syndrome (CCAS) that we described in adults with lesions confined to cerebellum, and in children surviving resection of cerebellar tumors anchored these observations in clinical neurology. The CCAS is characterized by impairments in executive function, visual spatial analysis, and selected aspects of language, with emotional dysregulation when lesions involve the cerebellar vermis. These findings are detected in children with complete or partial cerebellar agenesis, cerebellar hypoplasia with non-progressive cerebellar ataxia, and those born very preterm. Additionally, children with disorders that are defined by behavioral impairments including early infantile autism, dyslexia and attention deficit hyperactivity disorder also have a link to the cerebellum. Some adolescents develop an atypical psychosis some years after resection of cerebellar tumors in early childhood.

We have conceptualized the role of the cerebellum in these different clinical scenarios within the dysmetria of thought theory. This approach holds that (1) the cerebellum is an integral node in the distributed neural circuits subserving cognition; (2) there is topographic organization of cerebellar function in discrete anatomical and functional subunits; and (3) the uniform architecture of cerebellum facilitates a universal cerebellar transform, which when disrupted produces a universal cerebellar impairment, manifesting as ataxia in the motor system, and as the CCAS in the domains of cognition and emotion. The cerebrocerebellar system may be crucial for the developing brain, support sustaining projections between cerebral cortex and the cerebellum, and allow the cerebellum to modulate and automate the normal flow of information processing. Further studies are needed to explore these notions, and to assess whether early intervention can help compensate for the loss of cerebellar modulation of cognitive and social-emotional behaviors in children with cerebellar pathology.