Research

Our research examines modulators of the medial temporal hippocampal memory system across the adult human lifespan. Currently, we have projects ongoing that focus on the impact of cardio-respiratory fitness and exercise, aging, and psychosocial stress through the lens of racial discrimination in African Americans on functional and structural integrity of the human brain. To examine these research questions we use functional and structural MRI, cognitive and neuropsychological assessments, as well as biomarker essays.

 

Ongoing Projects

Racial Discrimination and Brain Health

Cognitive Study (Funded by the Alzheimer’s Association)

This pilot study examines whether chronic stress due to experiences of racism negatively affects brain function in two subgroups of Black seniors. A larger percentage of African Americans than Americans of European ancestry have Alzheimer’s disease. The reasons for this health disparity are unclear. Discrimination related to racial minority status – racism – is a known chronic stressor. The Alzheimer’s health disparity may, in part, be explained by differences in racism-related chronic stress. Experiences of racism are common among African Americans, the largest minority group in the United States. The hippocampus, a brain area critical for memory formation, is negatively impacted by both Alzheimer’s disease and chronic stress. The goal of this research study is to examine whether racism-related chronic stress in African American seniors could lead to poorer cognition and elevated cortisol (the “stress hormone”). As part of this research and in collaboration with the University of the Virgin Islands, St. Croix Campus, we are also comparing African American seniors living in the Boston area where they are members of the racial minority with African American/Afro-Carribean seniors living on St. Croix in the United States Virgin Islands where they are members of the racial majority on cognitive function and cortisol level.

MRI Study (Funded by the National Institute on Aging, NIH)

The hippocampus is a brain area critical for learning and memory that is negatively impacted by aging, Alzheimer’s disease, and chronic stress. Another well-established modulator of the hippocampal memory system is aerobic exercise. Aerobic exercise and chronic stress are both potent, but opposite modulators of the hippocampal memory system. The goal of this research is to examine how psychosocial chronic stress due to experiences of racism affects the hippocampal memory system, and to examine whether physical activity can buffer against the negative effects of racial discrimination related chronic stress.

 

Exercise and Fitness

Twelve-Week Exercise Training Study (Funded by the National Institute on Aging, NIH)

The overall goal of this project is to investigate the impact of aerobic exercise training on the medial temporal hippocampal memory system in initially physically inactive, healthy seniors. The medial temporal hippocampal memory system, including the entorhinal cortex, is critical for successful navigation and context-dependent memory formation. This brain region shows profound pathology in Alzheimer’s disease. Entorhinal and hippocampal atrophy rates accelerate with age in cognitively intact seniors, who also show impaired navigation and reduced activity in hippocampal and parahippocampal areas during allocentric navigation. Allocentric navigation is a form of flexible navigation that depends on successful encoding of relationships between landmarks in the environment. Physical exercise consistently appears as one of the most effective interventions to attenuate cognitive decline in aging and Alzheimer’s disease, and promotes healthy cognitive and brain aging. In humans, it is currently not well understood what neurobiological mechanisms underlie exercise-induced plasticity in the brain and in the entorhinal-hippocampal memory system in particular. We hypothesize that entorhinal functional integrity and entorhinal-hippocampal functional connectivity during allocentric navigation in a virtual environment are enhanced following exercise training in initially physically inactive seniors and that this enhancement is positively related to changes in cognition. To investigate the impact of aerobic exercise training on virtual navigation in aging, we are using a randomized, controlled clinical trial of exercise training with baseline and post-training assessments of behavioral performance on cognitive tasks of entorhinal and hippocampal integrity, aerobic fitness, and brain function using high-resolution functional and structural MRI.