Objective: To assess consolidation in amnestic mild cognitive impairment (aMCI), controlling for differences in initial learning and using a protracted delay period for recall.
Method: 15 individuals with aMCI were compared with 15 healthy older adult controls on a story learning task. Subjects were trained to criteria to equalize initial learning across subjects. Recall was tested at both the 30-min typically used delay and a 1-week delay used to target consolidation.
Results: Using repeated measures ANOVAs adjusted for age, we found group × time point interactions across the entire task between the final trial and 30-min delay, and again between the 30-min and 1-week delay periods, with aMCI having greater declines in recall as compared with controls. Significant group main effects were also found, with aMCI recalling less than controls.
Conclusion: Consolidation was impaired in aMCI as compared with controls. Our findings indicate that aMCI-related performance typically measured at 30 min underestimates aMCI-associated memory deficits. This is the first study to isolate consolidation by controlling for initial learning differences and using a protracted delay period to target consolidation in an aMCI sample.
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