What are the neural and behavioral profiles that serve successful cognitive aging? Because gene activity provides the fundamental building blocks for cellular function and dysfunction, gene expression patterns must be the cornerstone of successful cognitive aging. One mechanism underlying preservation or maintenance of cognitive function in aging may involve engagement of compensation, a concept that is emerging from human brain imaging data. We propose to identify possible compensatory mechanisms in aging, based on a multidisciplinary approach using microarray analyses to profile gene expression patterns in clinically well-characterized human brain tissues, complemented by animal models to test mechanisms by which physical activity prevents cognitive decline, followed by a translation of the animal data to humans.
In Aim 1, a set of clinically and pathologically well-defined human tissues will be used. We hypothesize that in the presence of pathology, compensatory gene expression will be mobilized to help preserve cognitive function. To address this, cases will be divided into cognitive quintiles, from which we will select the top 20th cognitive percentile, representing successful cognitive aging. To identify possible compensatory gene mobilization, we will assess gene expression profiles in the successful aging cohort, comparing gene those with low vs moderate levels of pathology. In addition, maintaining pathology constant at a moderate level, we will assess gene expression profiles across the top 4 cognitive quintiles to identify how gene expression patterns change with declining cognition. We hypothesize that declines in cognition will be reflected in a downregulation of select gene classes and genes, particularly genes linked to synaptic integrity, plasticity and energy metabolism. Various lifestyle factors are emerging as key for successful cognitive aging, in particular, increased physical activity. Thus, in Aim 2, using both human and animal tissue, we will evaluate the hypothesis that physical activity helps maintain successful cognitive aging by engaging compensatory gene mechanisms, particularly in vulnerable populations. In aged animals showing cognitive impairment, we hypothesize that exercise will reverse the impairment and mobilize a gene profile supportive of cognition/plasticity. In transgenic mouse models carrying the ApoE4 gene, a major risk factor for cognitive decline in humans, we test the hypothesis that exercise may be paradoxically more effective in E4 than E3 animals, in improving cognitive function and mobilizing plasticity-related gene expression. Finally, we seek to translate the animal research to a set of human cases where physical activity and cognition have been monitored, using post-mortem brain tissue to analyze brain gene expression patterns in high- active vs. relatively inactive people. Taken together, our project will provide new insight into gene expression profiles in the human that underlie successful cognitive aging, which are currently unknown.

Public Health Relevance

The human population is aging and thus there is a great need to promote successful cognitive aging. Our studies will define the gene expression profiles in the human brain of those who have achieved successful cognitive aging, and determine if exercise will build and strengthen the aging brain through action on gene expression. Accordingly, these studies will help provide a rational for including exercise as a formula to promote successful cognitive health during aging.

Agency
National Institute of Health (NIH)
Institute
National Institute on Aging (NIA)
Type
Research Project (R01)
Project #
5R01AG034667-04
Application #
8318662
Study Section
Special Emphasis Panel (ZAG1-ZIJ-5 (M2))
Program Officer
Wagster, Molly V
Project Start
2009-08-15
Project End
2014-07-31
Budget Start
2012-08-01
Budget End
2013-07-31
Support Year
4
Fiscal Year
2012
Total Cost
$336,684
Indirect Cost
$116,629
Name
University of California Irvine
Department
Internal Medicine/Medicine
Type
Organized Research Units
DUNS #
046705849
City
Irvine
State
CA
Country
United States
Zip Code
92697
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Berchtold, Nicole C; Sabbagh, Marwan N; Beach, Thomas G et al. (2014) Brain gene expression patterns differentiate mild cognitive impairment from normal aged and Alzheimer's disease. Neurobiol Aging 35:1961-72
Intlekofer, Karlie A; Berchtold, Nicole C; Malvaez, Melissa et al. (2013) Exercise and sodium butyrate transform a subthreshold learning event into long-term memory via a brain-derived neurotrophic factor-dependent mechanism. Neuropsychopharmacology 38:2027-34
Berchtold, Nicole C; Coleman, Paul D; Cribbs, David H et al. (2013) Synaptic genes are extensively downregulated across multiple brain regions in normal human aging and Alzheimer's disease. Neurobiol Aging 34:1653-61
Berchtold, N C; Castello, N; Cotman, C W (2010) Exercise and time-dependent benefits to learning and memory. Neuroscience 167:588-97