CANDIDATE: The candidate is an Instructor in the Section on Gerontology and Geriatric Medicine in the Department of Internal Medicine. Her previous research experience focused on the role of nutrition and obesity on physical function and disability in older adults. Receipt of this MRSDA will provide training in genetics and genetic epidemiology in order to examine gene-environment (e.g., nutrition and physical activity) interactions on physical function. The candidate will acquire didactic training in genetics, genetic epidemiology, and analysis of genetic data, as well as hands on training to identify polymorphisms in vitamin D-related genes. RESEARCH: This study will examine the association between vitamin D status, as indicated by circulating 25(OH)D and PTH, and vitamin D-related gene polymorphisms (e.g., vitamin D receptor (VDR) gene) on muscle strength and physical function in the LIFE Pilot Study, a randomized controlled trial contrasting the effect of a physical activity intervention versus a successful aging program on incident mobility disability in older adults. The hypotheses are that low vitamin D status and vitamin D- related gene polymorphisms will be associated with (a) lower levels of muscle strength and physical function at baseline;(b) higher rates of decline in muscle strength and physical function among successful aging program participants;and (c) lower rates of improvement in muscle strength and physical function among physical activity intervention participants. A replication dataset, the IDEA Study, will be used to reevaluate the effects of vitamin D-related gene polymorphisms on muscle strength and physical function. The knowledge she acquires will provide the basis for an independent research career in the areas of genetics and gene-environment interactions on physical function and disability. ENVIRONMENT: The research environment at Wake Forest University School of Medicine is excellent with senior experienced mentors in epidemiology, aging, and disability (Dr. Stephen Kritchevsky);molecular genetics (Dr. Donald Bowden);and analysis of genetic data (Dr. Carl Langefeld).

Public Health Relevance

Vitamin D insufficiency is common in older adults and may accelerate the disablement process. Understanding the relationship between vitamin D and variations in vitamin D-related genes and the maintenance of physical function is of significant public health importance.

National Institute of Health (NIH)
National Institute on Aging (NIA)
Research Scientist Development Award - Research & Training (K01)
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National Institute on Aging Initial Review Group (NIA)
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Nayfield, Susan G
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Wake Forest University Health Sciences
Internal Medicine/Medicine
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United States
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Nettleton, Jennifer A; Follis, Jack L; Ngwa, Julius S et al. (2015) Gene × dietary pattern interactions in obesity: analysis of up to 68 317 adults of European ancestry. Hum Mol Genet 24:4728-38
Vimaleswaran, Karani S; Berry, Diane J; Lu, Chen et al. (2013) Causal relationship between obesity and vitamin D status: bi-directional Mendelian randomization analysis of multiple cohorts. PLoS Med 10:e1001383
Houston, Denise K; Neiberg, Rebecca H; Tooze, Janet A et al. (2013) Low 25-hydroxyvitamin D predicts the onset of mobility limitation and disability in community-dwelling older adults: the Health ABC Study. J Gerontol A Biol Sci Med Sci 68:181-7
Houston, Denise K; Tooze, Janet A; Neiberg, Rebecca H et al. (2012) 25-hydroxyvitamin D status and change in physical performance and strength in older adults: the Health, Aging, and Body Composition Study. Am J Epidemiol 176:1025-34
Levin, Gregory P; Robinson-Cohen, Cassianne; de Boer, Ian H et al. (2012) Genetic variants and associations of 25-hydroxyvitamin D concentrations with major clinical outcomes. JAMA 308:1898-905
Houston, Denise K; Tooze, Janet A; Davis, Cralen C et al. (2011) Serum 25-hydroxyvitamin D and physical function in older adults: the Cardiovascular Health Study All Stars. J Am Geriatr Soc 59:1793-801
Houston, Denise K; Tooze, Janet A; Hausman, Dorothy B et al. (2011) Change in 25-hydroxyvitamin D and physical performance in older adults. J Gerontol A Biol Sci Med Sci 66:430-6