A vast network of arteries, capillaries, and veins is required to keep the 86 billion neurons in the brain functioning properly. Lab studies show that amyloid plaques and tau lead to blood vessel abnormalities and a breakdown of the blood-brain barrier. This vascular dysfunction appears to precede the full pathology of Alzheimer’s disease. Individuals with early cognitive dysfunction develop damage to the capillaries of the brain, and to the blood-brain barrier, regardless of the levels of accumulation of amyloid plaques or tau tangles. A new model of biomarkers has been suggested that links brain vascular changes to neurodegeneration. 

Berislav Zlokovic, M.D., Ph.D., Keck School of Medicine, University of Southern California