Assessing Exercise and Fitness-Related Brain Health Using Multi-modal Magnetic Resonance Imaging Outcomes

Several magnetic resonance imaging (MRI)-based modalities have provided insight into how acute and chronic exercise and physical activity impact brain health. Structural MRI-based measures provide information regarding brain volume and cortical thickness, diffusion-weighted imaging measures provide indices of white matter and gray microstructure, and cerebrovascular effects that may be assessed through measures of regional cerebral blood flow, and brain activation and neural networks can be indexed using task-based and connectivity-based functional MRI, respectively. In this chapter, a series of studies are described in which these multi-modal MRI outcomes, along with indices of neurocognitive function, have been documented after a brief walking exercise intervention in healthy older adults and those diagnosed with mild cognitive impairment. Finally, we provide some additional insight into the neurophysiological mechanisms that may be foundational for these effects, but are yet not measurable in humans. Multi-modal neuroimaging is a non-invasive method in humans to assess the potential mechanisms whereby acute and chronic exercise may exert benefits to brain function and neural networks related to cognition that may protect older adults from age-related cognitive decline and dementia.