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Midlife memory ability accounts for brain activity differences in healthy aging
Stockholm University, Faculty of Social Sciences, Department of Psychology.
Stockholm University, Faculty of Social Sciences, Department of Psychology. Centrum för forskning om äldre och åldrande (ARC), (tills m KI).
Stockholm University, Faculty of Social Sciences, Department of Psychology.
Umeå universitet.
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Cross-sectional neuroimaging studies suggest that hippocampal and prefrontal cortex (PFC) functions underlie individual differences in memory ability in elderly individuals, but it is unclear how individual differences in cognitive ability in youth contribute to cognitive and neuroimaging measures in older age. Here, a sample from a longitudinal population-based study (N = 201, aged 55-80) was used to investigate the relative influence of midlife memory ability and age-related memory change on memory-related BOLD-signal variability in healthy elderly. Hierarchical regression analyses showed that midlife memory ability, assessed 15-20 years earlier, explained at least as much variance as memory change in clusters in the left inferior PFC and the bilateral hippocampus, during memory encoding. Memory change estimates, however, were found to be more sensitive in detecting bilateral frontal regions specifically diagnostic of age-related memory change. These finding highlight challenges in interpreting individual differences in neurocognitive measures as age-related changes in the absence of longitudinal data, and also demonstrates the improved sensitivity of longitudinal measures.

Keyword [en]
cognitive aging; individual differences; fMRI; episodic memory; longitudinal assessment
National Category
Psychology
Research subject
Psychology
Identifiers
URN: urn:nbn:se:su:diva-93025OAI: oai:DiVA.org:su-93025DiVA: diva2:643863
Funder
Swedish Research CouncilKnut and Alice Wallenberg Foundation
Available from: 2013-08-28 Created: 2013-08-28 Last updated: 2013-08-29
In thesis
1. Brain characteristics of memory decline and stability in aging: Contributions from longitudinal observations
Open this publication in new window or tab >>Brain characteristics of memory decline and stability in aging: Contributions from longitudinal observations
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Aging is typically associated with declining mental abilities, most prominent for some forms of memory. There are, however, large inter-individual differences within the older population. Some people experience rapid decline whereas others seem almost spared from any adverse effects of aging. This thesis examined the neural underpinnings of such individual differences by using longitudinal observations of episodic memory change across 15-20 years, combined with structural and functional magnetic resonance imaging of the brain. Study I found significant correlations between volume and activity of the hippocampus (HC), and memory change over a 6-year period. That is, individuals with decline in HC function also had declining memory. In contrast, Study II showed that successfully aged individuals, who maintained high memory scores over 15-20 years, had preserved HC function compared to age-matched elderly with average memory change. The successful agers had HC activity levels comparable to those of young individuals, as well as higher frontal activity. Study III revealed that individual differences in memory ability and brain activity of elderly reflect both differential age-related changes, and individual differences in memory ability that are present already in midlife, when age effects are minimal. Specifically, memory scores obtained 15-20 years earlier reliably predicted brain activity in memory-relevant regions such as the frontal cortex and HC. This observation challenges results from previous cross-sectional aging studies that did not consider individual differences in cognitive ability from youth. Collectively the three studies implicate HC and frontal cortex function behind heterogeneity in cognitive aging, both substantiating and qualifying previous results from cross-sectional studies. More generally, the findings highlight the importance of longitudinal estimates of cognitive change for fully understanding the mechanisms of neurocognitive aging.

Place, publisher, year, edition, pages
Stockholm: Department of Psychology, Stockholm University, 2013. 114 p.
Keyword
aging, episodic memory, individual differences, longitudinal assessment, magnetic resonance imaging, hippocampus, frontal cortex
National Category
Psychology (excluding Applied Psychology)
Research subject
Psychology
Identifiers
urn:nbn:se:su:diva-93026 (URN)978-91-7447-734-4 (ISBN)
Public defence
2013-10-04, David Magnussonsalen (U31), Frescati Hagväg 8, Stockholm, 13:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 3: Manuscript.

Available from: 2013-09-12 Created: 2013-08-28 Last updated: 2013-09-12Bibliographically approved

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