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Our investigators

Jennifer Schrack, PhD, MS

Dr. JENNIFER SCHRACK is an Assistant Professor of Epidemiology and a core faculty member of the Center on Aging and Health at the Johns Hopkins Bloomberg School of Public Health. Dr. Schrack received her training at the University of Michigan (M.S.), the Johns Hopkins Bloomberg School of Public Health Department of Epidemiology (Ph.D.), and the National Institute on Aging (post-doctoral fellowship). Dr. Schrack has worked with the Baltimore Longitudinal Study of Aging (BLSA) since 2003 in multiple roles: as a clinical exercise physiologist, PhD student fellow (2007-2011), post doctoral fellow (2011-2012), and as a co-investigator (2012-present). Her research focuses on how energy expenditure and physical activity affect physical function in older populations. She also is a co-investigator on the Multicenter AIDS Cohort Study (MACS) and the Study to Understand falls Reduction and vitamin D in You (STURDY).


Seongjin Choi, PhD

Dr. Seongjin Choi joined the Intramural Research Program of the National Institute on Aging as an MRI researcher with the Longitudinal Studies Section and the Baltimore Longitudinal Study on Aging (BLSA). Dr. Choi is a biophysicist, specializing in magnetic resonance (MR) imaging and spectroscopy, investigating associations of MR-based findings with other biological and functional measurements from the BLSA to explore the basis and consequences of metabolic and energetic changes that are associated with human aging. He completed his PhD in the Biophysics Program at the Ohio State University and was trained as a postdoctoral researcher in the Department of Radiology at the Ohio State University Wexner Medical Center.

In his prior work, he investigated the use of magnetic resonance imaging in neuroimaging at ultra-high magnetic field (7 Tesla). Specifically, he conducted research on the structural integrity of neuronal fibers measured using diffusion tensor imaging (DTI) in traumatic brain injury (TBI), sports-related concussion, and post-stroke in human brain.

Since February 2013, he has focused on phosphorus (31P) and proton (1H) magnetic resonance spectroscopy (MRS) study in human skeletal muscle, mainly in the context of the BLSA. Investigation of muscle lipids (i.e., intramyocellular lipid: IMCL) using 1H-MRS and muscle bioenergetics (i.e., post-exercise phosphocreatine recovery rate) using 31P-MRS is of particular research focus. Initial findings have been correlated with a wide range of other biological and functional outcomes from the BLSA, including physical performance and aerobic capacity.


Brian Chen, Ph.D., M.P.H.

Dr. Brian Chen is an epidemiologist who uses high throughput technologies to gain insights into the biological underpinnings of aging and age-related diseases. His current work focuses on DNA methylation in relation to aging. He joined the Intramural Research Program of the National Institute on Aging (NIA) as an IRTA postdoctoral researcher. Prior to coming to the NIA, Dr. Chen worked at the National Heart, Lung, and Blood Institute's Framingham Heart Study. He received his PhD in epidemiology from UCLA and Master's in Public Health from UC Berkeley.


Qu Tian, PhD, MS

Dr. Tian is currently a postdoctoral fellow of Translational Gerontology Branch at the Intramural Research Program of the National Institute on Aging. With a unique training background in Epidemiology (PhD), Kinesiology (MS), and neuroimaging, Dr. Tian has a persistent interest in understanding the roles of physical activity and mobility in the aging brain and cognitive function. Prior joining the NIA in October 2013, Dr. Tian received her PhD in Epidemiology from University of Pittsburgh with a specialty in Neuroepidemiology. She obtained her Master’s Degree in Kinesiology with a specialty in exercise psychology from the University of Wisconsin – Milwaukee. She completed her undergraduate studies in Kinesiology from the Chengdu Sport University in China.
Dr. Tian’s prior work investigated how acute exercise affects attention in healthy adults and quantified the effects of physically active lifestyle and fitness on brain structure using advanced neuroimaging methodologies in older adults with a wide range of chronic disease conditions and physical functional limitations. At the NIA, she continues her research on how age-related brain atrophy in relation to activity and fitness. She is fascinated by understanding body-brain dynamics across the lifespan.


Bonnielin Swenor, Ph.D., M.P.H.

Bonnielin Swenor is an Assistant Professor at the Wilmer Eye Institute at Johns Hopkins University. She received an MPH concentrating in Epidemiology and Biostatistics and a PhD in Epidemiology from the Johns Hopkins Bloomberg School of Public Health. As a graduate student, Dr. Swenor was awarded the Dana Center for Preventive Ophthalmology Student Award, recognizing researchers committed to a career in public health ophthalmology. She completed a Postdoctoral Fellow at the National Institute on Aging in the Translational Gerontology Branch prior to returning to Wilmer in August of 2014. She maintains her association with the NIA and has “Special Volunteer” status.

Dr. Swenor’s research is at the intersection of aging and ophthalmology. Her primary research focus is to determine how visual impairment and eye disease effect functioning and quality of life trajectories in older adults. Dr. Swenor has epidemiologic expertise in longitudinal study design and analysis. Her current research includes examining neurocognitive, mobility, and reading outcomes in older adults with vision loss.


Eleanor M. Simonsick, PhD

Eleanor M. Simonsick received her PhD in Social and Behavioral Science and Health Education from the Johns Hopkins Bloomberg School of Public Health in 1988 and completed post-doctoral studies in the Department of Mental Health in 1990. She has been an epidemiologist and staff scientist in the Intramural Research Program (IRP) of the National Institute on Aging (NIA) ever since. Currently, Dr. Simonsick works in the Longitudinal Studies Section of the Translational Gerontology Branch where she serves as lead epidemiologist for the Baltimore Longitudinal Study of Aging (BLSA). She holds an academic appointment as an associate professor in the Division of Geriatric Medicine and Gerontology at the Johns Hopkins University School of Medicine. Dr. Simonsick has amassed over 250 publications in peer-review journals. Her primary area of expertise concerns assessment of higher-order physical function and changes with aging and evaluating the role and impact of social, behavioral, psychological and biological factors and conditions on maintenance and decline in function and the overall aging process.


Donnie Cameron Ph.D.

Dr. Donnie Cameron is a Medical Physicist who specializes in the development and application of new methods for magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS). He joined the Longitudinal Study Section of the National Institute on Aging in early 2014 as a Visiting Postdoctoral Research Fellow, after leaving his long-time home in the United Kingdom. Dr. Cameron received his Bachelor’s degree in Physics, Master’s in Medical Physics, and his Doctorate in Medical Imaging from the University of Aberdeen, Scotland—a university with a prodigious history in the development of MRI. He also spent one summer as an intern at ETH Zurich, an institution well-known for being Einstein’s alma mater, where he engaged in many fruitful collaborations. Dr. Cameron’s past work has ranged from the purely technical, to clinical applications—including computer-based MRI simulations, improvement of MRS techniques for assessment of breast cancer, and MRI characterization of cardiac tissue in patients with heart failure, myocardial infarction, and acute stress-induced cardiomyopathy. Aging is a new area of research for him, and his current work focusses on identifying new measures of muscle quality in older adults using magnetic resonance techniques of the lower limbs. To this end, he has been developing new MRI and MRS methods to achieve excellent data quality, and faster scan times.


Nancy Chiles Shaffer, Ph.D.

Dr. Nancy Chiles Shaffer joined the Intramural Research Program of the National Institute on Aging as a Postdoctoral fellow in October 2014. Dr. Chiles Shaffer received her PhD in Gerontology from the University of Maryland Baltimore.
Her research interests include body composition, physical function, mobility disability, and health disparities. Her doctoral dissertation examined the effect of sarcopenia, age-associated decreases in muscle, and peripheral nerve function on gait speed among older adults with and without diabetes. She also investigated whether these relationships differed by race and gender. At NIA, she hopes to continue her body composition research, particularly focusing on the impact of body mass on muscle. Dr. Chiles Shaffer also hopes to continue her focus on health disparities research.


Yuri A. Agrawal

My research is directed at studying age-related changes in vestibular function and implications for important geriatric outcomes, including gait impairment and falls. I employ a combination of vestibular physiologic testing and epidemiologic methods, and currently am collaborating with the NIA-funded Baltimore Longitudinal Study of Aging to study the epidemiology of vestibular dysfunction in that cohort and associations with mobility disability and cognitive decline. My long term research goals are to apply these epidemiologic insights towards the development of strategies to screen for, prevent and treat vestibular dysfunction and reduce associated disability in older individuals.


Edward G. Lakatta, M.D.

Dr. Lakatta is the founder and Director of the Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health. He also holds adjunct appointments as Professor, Department of Physiology, University of Maryland School of Medicine, and Professor, Cardiology Division, Johns Hopkins School of Medicine.

Dr. Lakatta received his M.D., Magna cum laude, at Georgetown University School of Medicine. Following an internship and residency in Medicine at Strong Memorial Hospital, University of Rochester, Rochester, N.Y., he trained in basic research for two years at the NIH. Subsequently, he completed his cardiology fellowship at Georgetown and Johns Hopkins University Schools of Medicine. This was followed by a year of basic research training in the Department of Physiology, University College and the Cardiothoracic Institute, London England.

He has made a sustained 40-plus-year commitment to a broad-based research career. His studies range from molecules to humans, including translation of novel findings into the clinical realm. The overall goals of his research program are 1) to identify age associated changes that occur within the cardiovascular system and to determine the mechanisms for these changes; 2) to determine how aging of the heart and vasculature interacts with chronic disease states to enhance the risk for CV diseases in older persons; 3) to study basic mechanisms in excitation-contraction coupling and how these are modulated by surface receptor signaling pathways in cardiac cells; 4) to elucidate mechanisms of pacemaker activity in sinoatrial nodal cells; 5) to elucidate mechanisms that govern cardiac and vascular cell survival; 6) to establish the potentials and limitations of new therapeutic approaches such as changes in lifestyle, novel pharmacologic agents or gene or stem cell transfer techniques in aging or disease states.

Dr. Lakatta is recognized as both nationally and internationally as an expert in cardiovascular research. He has authored over 450 original publications in top peer-reviewed cardiovascular journals, written over 250 invited reviews/book chapters, and delivered over 450 invited lectures. He is a member of multiple scholarly societies and journal editorial boards. Based upon his accomplishments, Dr. Lakatta has received numerous awards, among which has been election into the American Society for Clinical Research, the Association of American Physicians. Dr. Lakatta has also been elected as a fellow in the APS Cardiovascular Section, a fellow of the American Heart Association (F.A.H.A.) and is an Inaugural Fellow of the Council on Basic Cardiovascular Sciences of the American Heart Association. He is the recipient of Allied Signal Achievement Award in Aging, the Novartis Prize in Gerontology, the Irving Wright Award of Distinction of the American Federation for Aging Research (AFAR), the Frank J. O’Hara Alumni Award from the University of Scranton, the Distinguished Leader Award of the International Society of Heart Research (ISHR), the Eli Lilly Award in Medical Science, the Paul Dudley White Award in Cardiology, Distinguished Service Medals, Public Health Service, National Institutes of Health, National Institute on Aging and an Honorary Degree from the Universite D’Auvergne in Clermont, France.


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