Chris Martens

Associate Professor, Kinesiology & Applied Physiology University of Delaware

  • Newark DE

Prof. Martens's laboratory is interested in understanding mechanisms by which impaired vascular function contributes to cognitive declines.

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Researchers race to detect Alzheimer's sooner using $3.9M grant

Too often, people learn they have Alzheimer’s disease when it’s too late. The changes in the brain that lead to the disease manifesting with symptoms have already been occurring for decades. Researchers at the University of Delaware will attempt to detect the disease sooner through a new study that examines changes in the arteries and brain tissue in midlife adults in their 50s and 60s. The findings of this work, funded by a nearly $4 million grant from the National Institute on Aging (NIA), could identify the earliest mechanisms linking vascular aging to the loss of brain tissue integrity, leading to new targets for interventions aimed at preventing age-related cognitive impairment. “People who develop high blood pressure or stiffening of the aorta and carotid arteries in midlife are at a much higher risk for developing cognitive impairment or dementia in late life,” said Christopher Martens, the principal investigator of the study. Martens, an associate professor of kinesiology and applied physiology in UD's College of Health Sciences and director of the Delaware Center for Cognitive Aging (DECCAR), is working closely with Curtis Johnson, an associate professor of biomedical engineering in the College of Engineering and leader of the neuroimaging biomarker core within DECCAR, on research funded by a nearly $4 million grant from the National Institute on Aging (NIA), a division of the National Institutes of Health (NIH). “A lot happens as we age, so we’re aiming to pinpoint the timing and exact mechanisms that cause these changes in midlife adults,” Martens said. This latest grant extends DECCAR’s ongoing Delaware Longitudinal Study for Alzheimer’s Prevention (DeLSAP), which seeks to study how risk and protective factors for dementia are related and change over time. Those eligible for DeLSAP could also meet the criteria for participating in the new study. In his Neurovascular Aging Laboratory, Martens studies mechanisms leading to the stiffening of arteries, while Johnson is specifically interested in measuring the stiffness of the brain. “As a person ages, the brain gets softer and breaks down, and we’re looking to see whether changes in arterial stiffness and patterns of blood flow in the brain cause this decline,” Johnson said. Changes in blood flow to the brain come from controllable factors. Smoking, cardiovascular health, diet and exercise all impact blood flow positively and negatively. “A lot of aging research is done at the end of life,” Johnson said. “We want to look at midlife and try to predict what happens later in life so we can prevent it.” While the brain gets softer with age, arteries get stiffer. “We hypothesize that midlife increases in stiffness in blood vessels cause damaging pulsatile pressure to enter the brain,” Martens said. “We believe this is one of the reasons we start to develop cognitive issues at an older age because the brain is exposed to increased pressure; that pressure is likely inflicting damage on surrounding brain tissue.” In Johnson’s Mechanical Neuroimaging Lab, researchers will use high-resolution magnetic resonance elastography (MRE) to determine where brain damage occurs and what specific brain structures may be affected. “From an MRI perspective, most researchers look at AD and other neurodegenerative diseases like multiple sclerosis with an emphasis on detection in a hospital setting,” Johnson said. “Using highly specialized techniques we’ve developed, we focus on the earlier side and how these changes progress into disease from the neuroscience side, emphasizing prevention.” Together, they’ll seek to learn whether arterial stiffness causes the kind of cognitive impairment seen in AD or whether the decline is associated with a loss in the integrity of brain tissue. “If we can prove arterial stiffness is playing a causal role in cognitive aging, that would provide further support for focusing on blood vessel health as an intervention for delaying AD or other forms of dementia versus solely focusing on the brain,” Martens said.

Chris Martens

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Biography

Dr. Martens is interested in understanding the association between midlife cardiometabolic risk factors and late-life dementia with a primary focus on mechanisms of cerebrovascular dysfunction. His laboratory uses a range of techniques including cell culture, ultrasound, and magnetic resonance imaging (MRI) to investigate mechanisms of brain aging in humans. Dr. Martens is currently funded by the National Institutes of Health (NIH) to investigate the role of dietary added sugar intake on cerebral blood flow and brain tissue integrity in midlife adults and he is leading a clinical trial investigating a novel NAD+ boosting compound for improving brain health in older adults with mild cognitive impairment, a prodromal form of Alzheimer’s disease. He is also Director of the Delaware Center for Cognitive Aging Research (DECCAR) which provides infrastructure for research on Alzheimer's disease and related dementias within the state of Delaware.

Industry Expertise

Health and Wellness
Fitness

Areas of Expertise

Alzheimer's Disease
Aging
Clinical Trials
Cerebral Blood Flow
Vascular Aging

Media Appearances

Alzheimer's: Vitamin B supplementation could slow aging of neurons

Medical News Today  online

2023-03-03

If the brain cells can’t produce the energy they need to be able to function, then they can’t signal, and if nerve cells in the brain can’t signal effectively then cognition will be affected. Whether this is a cause of the disease or a symptom is unclear, said Dr. Christopher Martens, director of the Delaware Center for Cognitive Aging Research, and lead author of the current study.

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Natural dietary supplement can reach the brain, may prevent onset of Alzheimer’s

StudyFinds  online

2023-02-24

“NAD+ is gradually lost as we get older or develop chronic diseases. Loss of NAD+ is linked to obesity and other negative lifestyle habits like smoking,” says Christopher Martens, an assistant professor of kinesiology and applied physiology and director of the Delaware Center for Cognitive Aging Research, in a university release. “Because more NAD+ is needed to counteract those negative consequences, it’s more likely to be depleted in the face of negative lifestyle habits.”

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One step closer | UDaily

University of Delaware  online

2023-02-22

The discovery was made by Christopher Martens, assistant professor of kinesiology and applied physiology and director of the Delaware Center for Cognitive Aging Research, and Dr. Dimitrios Kapogiannis, a senior investigator at the National Institute on Aging. The finding is significant because it supports the idea that NR, upon reaching the brain, can alter the metabolism of relevant biological pathways involved in neurodegenerative diseases like Alzheimer’s. Their work, supported by an NIH grant, and in part by the Intramural Research Program of the NIH National Institute on Aging, was recently published in the journal Aging Cell.

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Articles

Vascular determinants of hippocampal viscoelastic properties in healthy adults across the lifespan

Journal of Cerebral Blood Flow & Metabolism

2023

Arterial stiffness and cerebrovascular pulsatility are non-traditional risk factors of Alzheimer's disease. However, there is a gap in understanding the earliest mechanisms that link these vascular determinants to brain aging. Changes to mechanical tissue properties of the hippocampus (HC), a brain structure essential for memory encoding, may reflect the impact of vascular dysfunction on brain aging. We tested the hypothesis that arterial stiffness and cerebrovascular pulsatility are related to HC tissue properties in healthy adults across the lifespan. Twenty-five adults underwent measurements of brachial blood pressure (BP), large elastic artery stiffness, middle cerebral artery pulsatility index (MCAv PI), and magnetic resonance elastography (MRE), a sensitive measure of HC viscoelasticity. Individuals with higher carotid pulse pressure (PP) exhibited lower HC stiffness (β = -0.39, r = -0.41, p = 0.05), independent of age and sex.

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Oral nicotinamide riboside raises NAD+ and lowers biomarkers of neurodegenerative pathology in plasma extracellular vesicles enriched for neuronal origin

Aging Cell

2023

Declining nicotinamide adenine dinucleotide (NAD+ ) concentration in the brain during aging contributes to metabolic and cellular dysfunction and is implicated in the pathogenesis of aging-associated neurological disorders. Experimental therapies aimed at boosting brain NAD+ levels normalize several neurodegenerative phenotypes in animal models, motivating their clinical translation. Dietary intake of NAD+ precursors, such as nicotinamide riboside (NR), is a safe and effective avenue for augmenting NAD+ levels in peripheral tissues in humans, yet evidence supporting their ability to raise NAD+ levels in the brain or engage neurodegenerative disease pathways is lacking. Here, we studied biomarkers in plasma extracellular vesicles enriched for neuronal origin (NEVs) from 22 healthy older adults who participated in a randomized, placebo-controlled crossover trial (NCT02921659) of oral NR supplementation (500 mg, 2x /day, 6 weeks).

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Blood lipid markers are associated with hippocampal viscoelastic properties and memory in humans

Journal of Cerebral Blood Flow & Metabolism

2021

Age-related memory loss shares similar risk factors as cardiometabolic diseases including elevated serum triglycerides (TGs) and low-density lipoprotein cholesterol (LDL-C) and reduced high-density lipoprotein cholesterol (HDL-C). The mechanisms linking these aberrant blood lipids to memory loss are not completely understood but may be partially mediated by reduced integrity of the hippocampus (HC), the primary brain structure for encoding and recalling memories. In this study, we tested the hypothesis that blood lipid markers are independently associated with memory performance and HC viscoelasticity-a noninvasive measure of brain tissue microstructural integrity assessed by high-resolution magnetic resonance elastography (MRE). Twenty-six individuals across the adult lifespan were recruited (14 M/12 F; mean age: 42 ± 15 y; age range: 22-78 y) and serum lipid profiles were related to episodic memory and HC viscoelasticity.

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Research Grants

The effects of added sugar intake on brain blood flow and hippocampal function in midlife adults

NIH/NIGMS P20 GM113125

09/01/2021-05/31/2026

NAD therapy for improving memory & cerebrovascular function in patients with MCI

NIH/NIA K01 AG054731

07/15/2017-03/31/2023

Accomplishments

Research Award, College of Health Sciences

2023

Fellowship, Institute on Methods and Protocols for Advancement of Clinical Trials in ADRD (IMPACT-AD)

2021

Early Investigator Award, North American Artery Society

2017

Education

University of Colorado Boulder

Postdoctoral Fellowship

2017

University of Delaware

PhD

Applied Physiology

2014

University of Delaware

BS

Exercise Science

2009

Affiliations

  • Delaware Center for Cognitive Aging Research (DECCAR)
  • UD Center of Biomedical Research Excellence (COBRE): Cardiovascular Health
  • American Physiological Society (APS)
  • American College of Sports Medicine (ACSM)
  • American Heart Association (AHA)