Verbal learning and memory in patients with dementia with Lewy bodies or Parkinson's disease with dementia

Abstract

This study compared verbal learning and memory in patients with autopsy-confirmed dementia with Lewy bodies (DLB) and patients with Parkinson's disease with dementia (PDD). A total of 24 DLB patients, 24 PDD patients, and 24 normal comparison participants were administered the California Verbal Learning Test. The three groups were matched on demographic variables, and the two patient groups were matched on the Mattis Dementia Rating Scale. The results indicated that DLB patients recalled less information than PDD patients on all but one recall measure and displayed a more rapid rate of forgetting. In contrast, the PDD patients committed a greater percentage of perseveration errors than the DLB patients. The two groups did not differ in the percentage of recall intrusion errors or any measures of recognition. A discriminant function analysis (DFA) using short-delay cued recall, percentage of perseveration errors, and List B recall differentiated the DLB and PDD groups with 81.3% accuracy. The application of the DFA algorithm to another sample of 42 PDD patients resulted in a 78.6% correct classification rate. The results suggest that, despite equivalent levels of general cognitive impairment, patients with DLB or PDD exhibit a different pattern of verbal learning and memory deficits.

Keywords:

• Parkinson's disease dementia
• Dementia with Lewy bodies
• Learning
• Memory
• Subcortical dementia

Acknowledgments

This research was supported in part by National Institute of Neurological Disorders and Stroke (NINDS) Grant (R01-41372) to J.V.F and National Institute on Aging Grant (R01-12963) to D.P.S.

Notes

¹Additional analyses were conducted excluding the 2 PDD patients on trihexyphenidyl because of its anticholinergic effects. Results were the same when these patients were excluded (see below) with the exception that significant differences among the three groups became nonsignificant on serial cluster ratio and free-recall intrusions.