DEFICITS IN VISUOSPATIAL ABILITIES ASSOCI ATED WITH PARKINSONS-DISEASE

Deficits in visuo-spatial abilities have frequently been reported in P arkinson's Disease (PD). However, the precise nature of these deficits remains unclear. The reason for this may lie in the type of tasks use d to assess spatial functions, many of them requiring either motor abi lities and/or contribution of other skills that are dependent upon the integrity of the frontal lobes. This study was thus designed to under stand better the nature of visuo-spatial impairments in PD and the exp erimental conditions that are apt to produce a deficit in this clinica l population. Hence, the performance of 15 non-demented patients with diagnosis of idiopathic PD was compared to that of 15 normal control s ubjects matched for age sex and education on three visuo-spatial tasks that did not solicit motor capacities. Two of them tested basic skill s: the first consisted of a discrimination task based on an adaptation of the Benton's Judgment of Line Orientation Test, whereas the second was a Mental Rotation Test that involved the discrimination of 3-dime nsional stimuli. The remaining test consisted of a problem-solving tas k, which measured visuo-spatial reasoning and mental flexibility, and was found to be sensitive to right frontal-lobe lesions. The results s howed that the parkinsonian patients were impaired on all three tasks compared to control subjects. These findings suggest that PD patients may not only present visuo-spatial deficits due to extraneous variable s in experimental tasks, but that they may also suffer from visuo-spat ial deficit per se. The pathophysiological changes associated with PD, which may explain these visuo-spatial deficits, are discussed.