Recognition memory in Parkinson's disease with and without dementia: evidence inconsistent with the retrieval deficit hypothesis.

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 out to 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.