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The Effects of Age & Apolipoprotein-E Genotype on Learning, Memory, and Metamemory for Odors
Murphy, ClaireGilbert, PaulDegeneffe, Charles
ix, 47 pages : illustrations
Episodic memory (EM) is well known to decline with age, and is especially affected in Alzheimer's disease (AD). Notably, however, EM declines are heterogeneous even among individuals with AD, and research indicates that there are a number of important risk and protective factors influencing the patterns and trajectories of these declines. One factor shown to influence aging EM is metamemory, which plays an essential role in the strategies used for encoding and retrieval of information, and the control of memory output. In general, better metamemory is associated with better memory performance, with most studies showing age-related metamemory declines that are worse in AD. However, studies also show that metamemory can be improved, even in those with more advanced AD. The main aim of the current study was to examine the relationships between EM, metamemory, and aging by comparing performance of healthy older and younger adults during an EM learning and recognition task. Measures of metamemory included the Memory Functioning Questionnaire (MFQ), as well as analysis of retrospective confidence judgments and mnemonic strategy use during the EM task. A known risk factor for AD as well as age-related EM declines is possession of an e4- allele of the apolipoprotein-E (ApoE) gene. Importantly, research has shown that carriers of the e4-allele display EM declines beyond those of normal aging, even when AD does not manifest. A second aim of the current study was to examine the effects of apoE genotype on the relationship between aging EM and metamemory. Studies have shown olfactory measures to be useful as early indicators of declines related to AD and apoE. Thus, the current study used an EM odor-learning and memory task, the California Odor Learning Test (COLT), to compare the effects of age, apoE genotype, and metamemory on EM task performance. Ability to detect odors was assessed and controlled for. Participants included 16 older adults (8 ApoE-e4 positive, 8 ApoE-e4 negative), and 25 younger adults (6 ApoE-e4 positive, and 13 ApoE-e4 negative). Age and ApoE groups did not significantly differ on any demographic variables. Results indicated that younger adults performed significantly better than older adults on all measures of recall consistency and recognition memory, as well as on all measures of metamemory abilities with the exception of self-reported use of mnemonics. Significant interaction effects between age and apoE genotype on short and long delay cued recall were found. As predicted, significant positive correlations were found among the recognition and recall measures of the COLT, among the task-based metamemory measures, as well as among the MFQ scales. These findings support the positive relationship between memory performance and metamemory abilities among both healthy older and younger adults, and further this idea to include the positive relationship of online mnemonic strategy use to both memory performance and metamemory abilities. For older adults, better metamemory has been associated with higher quality of life, while poor metamemory can produce serious day-to-day consequences for the individual and those they interact with, negatively affecting judgment and decision-making abilities. Thus, research on aging metamemory remains particularly important, and may help explain the heterogeneity seen in aging EM.
Includes bibliographical references (pages 36-40)
Master of Arts (M.A.) San Diego State University, 2014
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