MAPT and Alzheimer disease: NVU damage and loss of BBB integrity are well-recognised pathological features of AD that correlate with disease progression.83 Microbleeds can be detected in brain MR imaging of patients with LOAD and colocalise with Aβ plaques and infiltration of blood-derived products.84,85 Importantly, there is evidence to suggest that BBB and disruption precede Aβ and p-tau pathology.