Alzheimer disease (AD) has been viewed as the quintessential neurodegenerative disorder, and has defied decades of extensive research to find safe and effective disease-modifying treatment approaches. However, over the last 15¨C20 years, a new focus has developed on the role of vascular dysfunction in AD. Key to this approach is the consideration of the non-neuronal cells and other structural elements comprising the neurovascular unit (NVU), in particular pericytes. This review will examine the role of pericytes and the NVU in AD pathogenesis and the manner in which they interact with traditional factors, such as neuroinflammation, amyloid-beta, and apolipoprotein E. Based on the emerging evidence of the unique properties of pericytes, these ¡°forgotten cells¡± might represent a crucial nexus for solving the mysteries of AD.