CEREBELLUM AND COGNITION - THE NEUROPSYCHOLOGICAL AND NEURORADIOLOGICAL EVIDENCE

It is a classical topic of clinical neurology that cerebellar dysfunctions give rise to motor deficits but spare the sensory and mental domains. Since the last century, however, cognitive decline occasionally has been attributed to diseases and lesions of the cerebellum. In recent years this assumption has gained in importance. The recent literature puts forward four arguments in favour of this suggestion: a) The neocerebellum has large reciprocal fibre connections with the association areas of the cerebral cortex. b) Functional imaging studies revealed activation of circumscript cerebellar regions during cognitive tasks. c) Patients with cerebellar malformations and diseases, respectively, may present with psychopathological signs and neuropsychological deficits. d) Atrophy of the cerebellum has been reported in schizophrenic and autistic syndromes. The present review aims at a critical evaluation of the relevant clinical and neuropsychological literature. So far there is no convincing evidence that lesions and diseases restricted to the cerebellum give rise to dementia or to impaired verbal and visual memory functions. With respect to specific perceptual tasks such as the discrimination of time intervals, problem solving, and visuospatial functions, no definite conclusion is possible so far. Some studies revealed cerebellar atrophy in schizophrenic and autistic patients. However, the functional relevance of these findings must be questioned since cytoarchitectonic alterations in extracerebellar areas, e.g. the basal forebrain, are present in these disorders as well.