Verbal memory in non-demented patients with idiopathic Parkinson's disease

This study assessed the verbal memory functions of 20 patients with idiopathic Parkinson's Disease (PD) without any clinical evidence of dementia and 20 Medical Control (MC) patients with similar levels of physical disability. Performance was compared on tests of immediate recall, word list learning in intentional and incidental contexts, word completion priming, remote memory, metamemory and awareness of mnestic abilities. Significant differences were found in new learning of verbal material under incidental but not intentional learning conditions. Group differences were also observed on measures of remote memory and metamemory. The groups did not differ in word completion priming performance or recognition memory. These findings are consistent with other evidence suggesting that PD patients without dementia may have subtle cognitive deficits that affect memory performance. These may be attributable to impairments of attention allocation, formulation of retrieval strategies, and effortful learning associated with frontal lobe dysfunction. The group differences could not be attributed to impairments of intellectual functions, verbal fluency, level of physical disability, or mood disturbance.