MAPT and Alzheimer disease: Furthermore, the development of pathological hallmarks of AD, such as disrupted synaptic integrity, brain deposition of Aβ, and tau pathology [74], is facilitated by elevated levels of LDL (low-density lipoprotein) cholesterol, the essential lipoprotein that transports circulating cholesterol in the blood; (1) causes BBB leakage and increases brain levels of apoB [74,75]; (2) disrupts the neuronal endolysosome structure and function, another early pathological feature of sporadic AD [76].