IMPLICIT MEMORY IN ALZHEIMERS-DISEASE - A METAANALYSIS

Meta-analysis was performed on 33 articles (36 experiments involving 5 64 Alzheimer's disease [AD] patients and 592 controls). Overall, AD pa tients were significantly impaired on implicit memory tests, r = .163 (a difference of .329 SDs from normal performance). They were impaired on nonverbal tests (e.g., fragmented pictures), word stem completion, classical conceptual tests (e.g., free association), and on word-base d perceptual tests with long delays. However, they performed normally on word-based perceptual tests (e.g., perceptual identification of wor ds) with short study test delays. They also performed normally on word stem completion if they were older than 75, possibly because their ag e-matched controls were also impaired. These results are neither quali fied by study list length nor patient mental status. None of the theor ies in the field is compatible with the results.