We found that BBB breakdown (evidenced by accumulation of fibrinogen in post‐mortem tissue from individuals with AD, VaD and mixed dementia) was associated with increased endothelin‐1 (EDN1), more severe hypoperfusion (lower myelin‐associated glycoprotein:proteolipid‐1 ratio), SVD, Aβ and tau [119]. This evidence concerns the gene MAPT and Alzheimer disease.