The currently recognized mechanisms of AD are amyloid β protein (Aβ) toxicity (Wang et al., 2016), microtubule-associated protein tau phosphorylation (Bakota and Brandt, 2016), cholinergic system damage (Kamkwalala and Newhouse, 2017), insulin resistance (Diehl et al., 2017), oxidative stress response (Kamat et al., 2016), blood-brain barrier (BBB) damage (Cai et al., 2018), neuroinflammatory response (Heppner et al., 2015), and deposition of α-synuclein (α-syn; Twohig and Nielsen, 2019). Here, MAPT is linked to Alzheimer disease.