[show abstract][hide abstract] ABSTRACT: In a recent study, performance on a certain kind of prospective memory task (PM), labeled focal PM, was sensitive to the very early stages of Alzheimer's disease (AD; Duchek, Balota, & Cortese, 2006). This study sought to replicate and extend these findings by investigating both focal and nonfocal PM, as well as possible influences of alleles of the apolipoprotein E (ApoE) gene.
Thirty-five healthy older adults and 33 adults in the very earliest stages of AD, as determined by the clinical dementia rating scale, completed both focal and nonfocal PM tasks. Performance on these tasks has been linked to qualitatively different cognitive processes (Scullin, McDaniel, Shelton, & Lee, 2010), thereby providing leverage to illuminate the specific processes that underlie PM failures in very early AD. Approximately half of the adults in each group were ApoE e4 carriers and half were noncarriers. We also obtained participants' scores on a battery of standard psychometric tests.
There was a significant interaction between the type of PM task and dementia status, p < .05, ηp² = .12, demonstrating that the AD-related decline was more robust for focal than for nonfocal PM. Further, focal PM performance significantly discriminated between the very earliest stages of AD and normal aging, explaining variance unique to that explained by typical psychometric indices. ApoE status, however, was not associated with PM performance.
The pronounced deficit observed in the focal PM task suggests that spontaneous retrieval processes may be compromised in very early AD.
[show abstract][hide abstract] ABSTRACT: This study explored the ability to control familiarity-based information in a memory exclusion paradigm in healthy young, older adults, and early stage DAT individuals. We compared the predictive power of memory exclusion performance to standard psychometric performance in discriminating between aging and the earliest stage of DAT and between APOe4-present and APOe4-absent genotype in healthy control individuals. Participants responded "yes" to words that were previously semantically encoded, and "no" to words that were previously read aloud and to new words. The number of targets and distractors on the read "distractor" list was manipulated to investigate the degree to which aging and DAT influence the ability to recollect in the face of distractor familiarity due to repetition. Memory exclusion performance was better for healthy older adults than very mild DAT individuals and better for healthy control individuals with APOe4 allele than those without APOe4 allele even after controlling for standard psychometric performance. Discussion focuses on the importance of attentional control systems in memory retrieval and the utility of the opposition paradigm for discriminating healthy versus pathological aging.