Pathological changes within the cerebral vasculature in Alzheimer’s disease: New perspectives

Abstract

Cerebrovascular disease underpins vascular dementia (VaD), but structural and functional changes to the cerebral vasculature contribute to disease pathology and cognitive decline in Alzheimer's disease (AD). In this review, we discuss the contribution of cerebral amyloid angiopathy and non‐amyloid small vessel disease in AD, and the accompanying changes to the density, maintenance and remodelling of vessels (including alterations to the composition and function of the cerebrovascular basement membrane). We consider how abnormalities of the constituent cells of the neurovascular unit – particularly of endothelial cells and pericytes – and impairment of the blood‐brain barrier (BBB) impact on the pathogenesis of AD. We also discuss how changes to the cerebral vasculature are likely to impair Aβ clearance – both intra‐periarteriolar drainage (IPAD) and transport of Aβ peptides across the BBB, and how impaired neurovascular coupling and reduced blood flow in relation to metabolic demand increase amyloidogenic processing of APP and the production of Aβ. We review the vasoactive properties of Aβ peptides themselves, and the probable bi‐directional relationship between vascular dysfunction and Aβ accumulation in AD. Lastly, we discuss recent methodological advances in transcriptomics and imaging that have provided novel insights into vascular changes in AD, and recent advances in assessment of the retina that allow in vivo detection of vascular changes in the early stages of AD.

Abstract

Structural and functional changes to blood vessels not only underpin disease pathogenesis in vascular dementia but are also major contributors to cognitive decline and disease progression in Alzheimer’s disease. We provide an updated review on the clinical and neuropathological vascular features (SVD, CAA) and underpinning functional changes to blood vessels in relation of disease pathology in Alzheimer’s disease. We also discuss recent methodological advances within the field that have provided novel insights into vascular changes in AD, including transcriptomics, imaging, and retinal assessment providing a window of opportunity for future clinical intervention.