Functional and Structural MRI in Alzheimer’s Disease: A Multimodal Approach

Abstract

Alzheimer’s disease (AD) is a progressive neurodegenerative brain disorder and the most common cause of dementia in the elderly. Neuroimaging techniques have revolutionized research on the pathogenetic processes in AD, as they allow tracking AD-related pathological changes in the living brain with ever-increasing detail. The most widely used MRI-based imaging techniques for the study of AD-related brain changes include structural MRI for assessment of gray matter atrophy, diffusion-weighted MRI for assessment of reduced white matter fiber integrity, and functional MRI for assessment of alterations in brain activation and functional network organization. In this chapter, we will describe how these imaging techniques have furthered our understanding of the specific pattern of structural and functional brain changes as they spread through the brain during AD pathogenesis and how these changes are associated with the expression of clinical symptoms. We will further describe how MRI-based technology is being used to study the neural mechanisms by which specific molecular, genetic, and lifestyle factors modify the risk for, and the clinical course of, AD. As a direct clinical application, increased knowledge about the characteristic brain changes in the course of AD pathogenesis can be used for the development of stage-specific disease biomarkers that increase the certainty of clinical diagnoses and may even allow predicting an individual’s risk for future cognitive decline and development of dementia. Finally, multimodal imaging approaches help to advance the study of disease mechanisms in AD through the assessment of interrelations among the diverse structural and functional brain changes and may further increase the accuracy of imaging-based diagnostic models by providing a more comprehensive picture of an individual’s pathologic state.