Methodologic Considerations in Neuropsychologic Testing of Ataxic Patients

To the Editor.  —In analyzing the neuropsychologic changes in patients with olivopontocerebellar atrophy (OPCA), Berent et al¹ concluded that there are no neuropsychologic disorders in these patients because "motor dysfunction and depressed mood could leave patients with OPCA appearing to be impaired in memory, even demented, when they are not." Since the first description from our laboratory of the cause-effect relationship between cerebellar damage and neuropsychologic impairment,² many articles have pointed out the role of the cerebellum in cognition in both humans^3-7 and animals.⁸ The main challenge in the neuropsychological evaluation of patients with cerebellar damage is to dissociate cognitive from motor dysfunction. Berent et al¹ attempted to achieve this by means of a statistical procedure (analysis of co