Visuospatial learning impairment in Parkinson Disease]

Despite the fact that different mnesic processes have been found to be impaired in Parkinson's disease, spatial learning is still an unstudied aspect. The aims of the present study were to evaluate visuospatial and verbal learning in nondemented patients with Parkinson's disease (PD) (N=20), and to assess the influence of processing speed, attention, working memory, and visuospatial perception. Compared to controls (N=20), PD patients had a poorer performance on Spatial Span, Judgment Line Orientation Test (JLOT), and 8/30 SRT. No differences were found between patients and controls in other functions assessed. Regression analysis showed that performance on Spatial Span and JOLT explains 58.2% of the variance of total spatial learning. Our results suggest an early impairment of spatial working memory and visuospatial perception in patients with PD. The visuospatial learning impairment may result from a primary deficit in these functions. These results suggest a global affectation of visuospatial processes, which may arise from dysfunction of the cortico-striatal circuits that include prefrontal and posterior parietal cortex.