Aghjayan, Sarah
(2024)
Associations Between Episodic Memory and Hippocampal Volume in Late Adulthood.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
There are various ways of conceptualizing and assessing episodic memory (EM), but different EM tasks are only moderately correlated with each other, suggesting that EM might not be a unitary construct. Further, various EM tasks exhibit disproportional task demands on the hippocampus and differentially reflect hippocampal volume (HV) degeneration – one of the strongest predictors of Alzheimer’s disease. Therefore, it is unclear if variation in EM performance is a meaningful indicator of risk for developing Alzheimer’s disease. This study established a structural equation model to examine the covariance structure and distinctiveness of EM tasks and assessed whether these relate differently to HV. This study examined 648 older adults (M=69.88). EM was assessed using seven of the most commonly used tasks in neuropsychological testing settings. Automated Segmentation of Hippocampal Subfields was used to segment the hippocampus. A confirmatory factor analysis was used with residual covariances included and loadings freely estimated. Hierarchical regression models were used to test the associations between the observed factors of EM and HV. A model with three first-order subfactors (verbal immediate recall, verbal delayed recall, and visuospatial) derived from a second-order general EM domain factor had the best model fit. All three subfactors and the general EM domain factor significantly explained a similar amount of variance in total, left, and right HV. In addition, all subfactors were significantly associated with CA1, entorhinal cortex, and subiculum volume, only the verbal immediate recall and verbal delayed recall subfactors were significantly associated with CA3 volume, and none of the three subfactors were significantly associated with CA2 or dentate gyrus volume. These results suggest that traditional EM tasks are measuring the same overarching construct, but different task conditions are tapping into different complex processes associated with EM. Further, performance across the observed factors only accounted for a small portion of the variance in HV, suggesting that HV might not be a strong marker of EM ability before clinically observable cognitive deficits are present. Lastly, findings from this study suggest that different hippocampal subfields are not uniformly involved in managing and supporting EM, and they may be preferentially important for various processes.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
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| Date: |
27 August 2024 |
| Date Type: |
Publication |
| Defense Date: |
19 April 2023 |
| Approval Date: |
27 August 2024 |
| Submission Date: |
1 June 2023 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Number of Pages: |
81 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Dietrich School of Arts and Sciences > Psychology |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
episodic memory, hippocampal volume, older adults |
| Date Deposited: |
27 Aug 2024 14:36 |
| Last Modified: |
27 Aug 2024 14:36 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/44928 |
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