CAA-related enlarged perivascular spaces are associated with abnormal angioarchitecture in human brain tissue: A key role for white matter atrophy?

Cerebral Amyloid Angiopathy, a common age-related small vessel disease leading to hemorrhagic stroke, shares many characteristics with Alzheimer's disease: toxic amyloid deposits, microvascular alterations and enlarged perivascular spaces (EPVS). Together, PVS enlargement, reduced amyloid-β clearance and further accumulation form a vicious cycle underlying disease progression. Yet, the neuropathological correlates of EPVS, including the associated angioarchitecture, are poorly understood. We provide quantitative 3D reconstructions of human brain microvascular networks and their topographical associations with EPVS in large volumes of cleared human tissue spanning over the gray/white matter interface. We reveal the existence of six vessel/PVS morphotypes, including sinusoid and helical vessels, enclosed in increasingly enlarged PVS, and increasingly disconnected from their surrounding network. Based on the buckling of elongated structures, we discuss how they likely result from generic processes of mechanical origin, driven by white matter atrophy, thus advancing our understanding of the pathophysiological overlap between amyloid-related and cerebrovascular disease.