Influence of Probable Alzheimer's Disease on Multiplication Verification and Production Abstract

Abstract

We compared the multiplication verification and production performances of healthy younger (n = 20) and older (n = 20) adults to that of mildly demented (Mini Mental Status Exam range: 19–27) individuals diagnosed with probable Alzheimer's disease (n = 18). While healthy older adults and Alzheimer's patients were slower than younger adults, the older adults actually showed significantly smaller problem-size effects for verification and production reaction time (RT) tasks. These results suggest that retrieval of multiplication fact knowledge from long-term memory for multiplicands greater than zero remains largely intact in mildly demented individuals diagnosed with probable Alzheimer's discase, although these individuals may have more difficulty with volitional retrieval because group differences were larger for some production analyses (require volitional retrieval) than for verification analyses (simply requires familiarity). However, for problems involving zero multiplicands (but not 1’s), healthy older adults and especially Alzheimer's patients showed significantly higher error rates than younger adults, suggesting that rule retrieval of correct solutions in memory was impaired in both of these older groups for problems involving zero operands. Also, when RT was regressed on problem size across groups, there was no effect for problem size for the production task for Alzheimer's patients—but there was for healthy younger and older adults. Finally, when verifying problems, there was a significant problem size effect of comparable magnitude for all three groups.