Stroke, Cognitive Function, and Alzheimer's Disease

Ischemic stroke is a leading cause of death and disability worldwide. Perhaps more importantly, stroke can lead to various cognitive changes, referred to collectively as vascular cognitive impairment (VCI). In addition, stroke increases the risk of vascular dementia (VaD), which is the most frequently encountered dementia after Alzheimer's disease (AD). Traditionally, the pathogenic causes and underlying mechanisms of VCI and AD have been considered separate entities. However, several lines of evidence now indicate an overlap between vascular and neurodegenerative causes of dementia. Indeed, vascular factors are now thought to be involved in both VCI and AD. Furthermore, clinical and experimental studies show that ischemic stroke increases the risk of AD, and may influence dementia expression by aggravating Alzheimer's-associated neuropathology. In this chapter, we begin by briefly summarizing the pathogenesis of stroke, before highlighting current evidence for the involvement of vascular factors in both VCI and AD, with a particular focus on the neurovascular unit. Finally, we will discuss clinical and experimental evidence for poststroke VCI and AD.