Recognition Memory in Parkinson’s Disease With and Without Dementia: Evidence Inconsistent with the Retrieval Deficit Hypothesis

Abstract

Parkinson’s disease (PD) has been associated with a pattern of performance on memory tests in which free recall is impaired but recognition and cued recall are intact, indicating problems with memory retrieval. Recent findings suggest that PD patients exhibit deficits in recognition as well as free recall, however. The current study set outto provide clear evidence that recognition and cued recall are not intact in PD. Ninety-nine idiopathic PD patients were administered the California Verbal Learning Test and their performance was compared to a well-matched normative sample. A profile analysis revealed that nondemented patients exhibited deficits on measures of cued recall and delayed recognition that were similar in magnitude to that of free recall. This was also the case for the cued recall deficits exhibited by demented patients; however, in this group recognition was worse than free recall. In both groups poor recognition appeared due to an elevated number of false positive errors. These results are inconsistent with the retrieval deficit hypothesis but support the notion that PD memory problems are secondary to prefrontal dysfunction.

Acknowledgements

This research was supported through PHS grant NS39121. The authors thank Drs. David King and Dawn Levine, who performed the neuropsychological evaluations of these patients with the assistance of their postdoctoral fellows, Drs. Stacey Rohrer and Vicki Evans. We also thank Margaret Sanders and Nuny Khamphay for their invaluable assistance with data collection and maintenance, and Dr. Conrad Pappas, the director of the service from which patients are recruited. Without his support this work would not be possible.

Notes

For a sample of z-scores (with a population mean of zero and standard deviation of one) the value for the inferential z-test is equal to the product of the sample mean and the square root of the sample size.