Probing Cerebrovascular Alterations in Alzheimer's Disease Using MRI: From Transgenic Models to Patients

Vascular abnormalities commonly coexist with the histological features of Alzheimer's disease (AD). Deposition of amyloid-β peptide in cerebral vessel walls, known as cerebral amyloid angiopathy, is very frequent, but it is unclear whether CAA is triggering AD or is contributing to later phases in pathology. In this paper, the use of MRI to detect cerebrovascular changes in murine models of AD and in patients is addressed. As reduced blood flow is a consistent physiological deficit reported in individuals suffering from AD, perfusion MRI has a particular relevance. Moreover, because of their sensitivity to turbulences, angiographic or phase-contrast techniques have the potential to detect small alterations of vessels translating into minor flow disturbances. Cerebral blood volume assessments allow to study functional deficits before gross morphological alterations of associated brain regions. Despite initial encouraging results, the discussed techniques still need to be properly validated, either diagnostically or as a tool for drug discovery. The further characterization in murine models along tests in large-scale, epidemiologically rigorous, human studies are going to contribute to establish the true utility of MRI as a tool to visualize AD-related cerebrovascular alterations in experimental animals and in patients.