MAPT and Alzheimer disease: Conversely, when the tau is phosphorylated and, therefore, not able to attach to the microtubule, as happens in hyperphosphorylation in AD, there is decreased bundling and stability of microtubules resulting in disturbed neuronal architecture and impaired axonal transport; all of which ultimately lead to cell death (Amadoro et al., 2011; Youdim et al., 2003).