Neuroimaging in Dementias

Late-onset dementia is usually a multifactorial disease wherein cumulative pathological brain insults (of more than one pathology) results in progressive cognitive decline that ultimately leads to impairment in ability to function at work and/or perform usual activities/tasks. Until recently, postmortem examination has been the only way to accurately determine the underlying pathology that led to dementia. However with the recent emergence of advanced imaging technologies, imaging indicators of disease that closely reflect the underlying pathology have been found to be very useful in aiding the prediction of the underlying dementia pathology. In this chapter we will cover the three common neurodegenerative dementias-Alzheimer disease, dementia with Lewy bodies (DLB), and frontotemporal dementia (FTD). For each of these dementia subtypes we will discuss the clinical manifestation of the disease, the pathologies underlying the disease and the neuroimaging correlates that can be observed using the currently available imaging methods.