MAPT and Alzheimer disease: Thus, any changes in the BBB function may allow toxic molecules access to the brain and impair the clearance of neurotoxic molecules, such as amyloid-β (Aβ) peptides and tau proteins, which could lead to oxidative stress, neuroinflammation, disruption of the functional brain network, and impairment in cerebral blood flow revealed in patients with mild cognitive impairment (MCI), a condition that could advance to AD and related dementias [8].