Where we've been and where we're going in the future!
Our research in cardiovascular, cerebrovascular, and exercise physiology has engaged with diverse populations across the lifespan and around the globe, from hot environments in firefighting protective equipment, to high altitude and the base camp of Mt. Everest! Below is a brief summary of our prior work and where it may take us in the future!
Sex differences in vascular mechanisms of brain health:
Alzheimer’s disease is forecast to impact nearly 14 million adults by 2050, with women impacted 2.5 times more than men. The mechanism behind these sex differences in brain health and Alzheimer’s disease risk is unknown but may be related to vascular health in middle age, a critical window during which vascular health is highly related to later-life brain health. Indeed, our current and prior work have shown women exhibit greater impairments in brain blood flow and may have less inherent protection against damaging blood flow patterns that may render the brain more vulnerable to detrimental age-related changes in blood flow and artery function. Within our studies, we are examining sex differences in vascular function and brain blood flow in middle-aged men and women, and also examining the role of menopause to understand if vascular mechanisms of brain health in middle age contribute to the greater cognitive disease burden among women in later-life. Our initial studies characterizing these differences will be followed by studies identifying therapeutic strategies to target mechanisms underlying these sex differences in brain aging and reduce sex differences in Alzheimer's disease burden.
Early vascular aging in children: contributors and consequences
Accelerated arterial stiffening is a hallmark of early vascular aging. We were one of the first to identify (1) greater arterial stiffness in African American children compared to white children, and (2) arterial stiffness contributes to pulsatile (i.e. discontinuous) blood flow in the brain among children, which could damage brain structures over time. Recently, we showed that physical activity is associated with a more favorable hemodynamic profile in children that could slow vascular aging, emphasizing the importance of exercise and physical activity in childhood. Taken together, these data highlight arterial stiffness as a vascular mechanism that can be targeted to abrogate early vascular aging and racial differences in cardiovascular and brain health.
Examining changes in cognitive function with exercise and environmental challenges:
Cognitive function remains one of the most foundational measures of brain health and function in the context of aging, disease (e.g. Alzheimer's disease, Multiple Sclerosis, etc.), and challenging environmental conditions. Although our data and others, have broadly shown acute aerobic and resistance exercise improves cognitive function, standard metrics of cognitive performance (accuracy, reaction time) contain a degree of inherent noise. We have utilized mathematical models of decision-making in collaboration with Dr. Corey White to provide a more detailed characterization of cognitive function that can separate behavioral strategies (e.g. caution, bias) that create noise in cognitive data from actual changes in the underlying decision making process (i.e. strength of evidence on which the decision was made). We have used this novel approach to understand how changes in bias, caution, and processes outside of the decision-making process (i.e. encoding/motor response) contribute to changes in cognitive function with aerobic exercise, high altitude, and exercise at high altitude. These data helped us establish a body of work incorporating novel mathematical models of decision-making to further understand behavioral mechanisms behind changes in cognitive function in the context of exercise and challenging environmental extremes, which we continue to use and incorporate into our assessments of cognitive function today.
Cerebro
vascular responses to high altitude environments and its relation to cognitive function:
Hypoxia challenges the cardiopulmonary system to maintain oxygen delivery to the brain, potentially contributing to cognitive dysfunction often observed at high altitude. Our prior work has shown that brain blood flow to the brain during cognitive activity is preserved at high altitude despite reductions in cognitive function in both the laboratory (hypoxic chamber) and field setting (Nepal Himalaya, Mt. Everest base camp). We have also shown that ingestion of a dietary vasodilator (nitrate, beet root juice) did not alter cerebrovascular or cognitive responses to hypoxia. This work in high altitude physiology has informed the manner in which we currently measure brain blood flow and has provided some of the greatest views ever seen while collecting data during a 2018 research expedition and study abroad program to Mt. Everest base camp. We hope to plan another research expedition to the Nepal Himalaya and Mt. Everest Base Camp within the next 5 years! Read about the 2018 expedition from the students' and researchers' perspective here! We also went back to EBC in May of 2023 and the blog can be found here, with the video below! Our plan is to start to put together research expeditions from Iowa State University with Iowa State students in ~2025-2026.