VISUOSPATIAL MEMORY DEFICITS AT DIFFERENT STAGES OF PARKINSONS-DISEASE

Groups of patients with idiopathic Parkinson's disease (PD), either me dicated or unmedicated, were compared with matched groups of normal co ntrols on a computerised battery of tests designed to investigate spat ial working memory, visuospatial recognition memory and learning. The medicated PD patients were subdivided into those with mild and severe clinical disability on the basis of Hoehn and Yahr ratings, thus makin g three groups of PD patients in all. In a test of spatial recognition memory, a significant impairment was only evident in those PD patient s who were medicated and had severe clinical symptoms (Hoehn and Yahr stage III-IV). In contrast, none of the three patient groups were impa ired in a complementary test of visual pattern recognition memory. Whi lst all three patient groups performed well in a test of simultaneous visual matching to sample, medicated patients (MED PD) with severe cli nical symptoms were significantly impaired when a short (0-12 sec) del ay was introduced. In a test of paired associates learning requiring b oth visual pattern and visuospatial memory, deficits in learning and m emory were only evident in the severely impaired MED PD group. In cont rast, in a test of spatial working memory known to be sensitive to fro ntal lobe damage, significant impairments were found in both groups of medicated PD patients and particularly in those patients with more se vere clinical symptoms. Taken together, the results suggest that there are multiple memory impairments in PD which may differentially depend on the clinical severity of the disease.