Abstract
Visuospatial deficits in basal ganglia disease may be a non-specific function of the severity of dementia or they could reflect disease-specific impairments. To examine this question, Huntington (HD) patients, demented and non-demented Parkinson (PD) patients and healthy controls were examined with neuropsychological tests emphasising visuospatial abilities. Global intellectual function and general visuospatial cognition were less efficient in the two demented patient groups relative to both controls and non-demented PD patients and they did not differ significantly between non-demented Parkinsonians and controls nor between demented PD and HD patients. However, HD patients but not demented PD patients were impaired on a test of person-centred spatial judgement compared to non-demented subjects while demented PD patients scored significantly lower than HD patients on a test of field independence. Factor analysis yielded a factor reflecting general visuospatial processing capacity which discriminated between demented and non-demented PD patients but not between demented PD and HD patients. A unique factor associated with the manipulation of person-centred space discriminated between demented PD and HD patients. These results suggest general visuospatial processing is impaired as a non-specific function of dementia presence in HD and PD. Abnormalities in circumscribed aspects of visuospatial function, on the other hand, may differentiate between HD and PD, suggesting differential involvement of the basal ganglia in the respective illnesses.
Highlights
Visuospatial function, i.e. cogmtlve processes mediated by visual input rather than language, is consistently found to be affected in basal ganglia disorders
A more global dementia is associated with these two basal ganglia diseases
In HD, the presence of dementia is well established (Granholm and Butters, 1988; Starkstein et al, 1988; Saint-Cyr et al, 1988; Weinberger et al, 1988; Goldberg et al, 1990) and a further investigation reported a significant association between impairment of general visuospatial ability and magnitude of dementing symptoms in HD patients (Mohr et al, 1991)
Summary
Visuospatial function, i.e. cogmtlve processes mediated by visual input rather than language, is consistently found to be affected in basal ganglia disorders (for example, Brouwers et al, 1984; Beatty, 1989; Mohr et al, 1991; Levin et al, 1991; Drachman et al, 1982; Filoteo et al, 1995). Cognitive deficits in specific aspects of visuospatial function have been demonstrated (Fedio et al, 1979; Jason et al, 1988), when manipulation of person-centred space (as opposed to environment-or object-centred space (Olson and Gettner, 1995, Brouwers et al, 1984; Potegal, 1971)) is required Severity of this deficit has been linked to duration of symptomatic expression of disease in HD patients (Mohr et al, 1991). The effect on visuospatial functioning of presence or absence of dementia and of distinctive motor disease involving the basal ganglia could be ascertained independently
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