Alzheimer’s disease is the leading cause of dementia and has been historically characterized by amyloid-beta plaques within the brain parenchyma and neurofibrillary tangles within neurons. However, it is now clear that cerebrovascular pathology and associated impairments in cerebral blood flow, blood–brain barrier function, and clearance of brain waste are key contributors to Alzheimer’s disease progression. This chapter will discuss the microvascular changes that occur in Alzheimer’s disease, related dementias, and aging with an emphasis on mural cells and their dysfunction during disease. In particular, pericytes will be reviewed in relation to the varying microvascular zones in the brain and the different cellular and acellular components of the neurovascular unit. Our discussion will synthesize data from preclinical and clinical studies, including examples that have used classical and novel technologies to shed light on vascular contributions to dementia.