MAPT and Alzheimer disease: Neuronal transport disruption is considered an important form of tau toxicity, which is an early phenomenon and underlying cause of neurodegenerative conditions including AD (Lin and Beal, 2006; Morfini et al., 2009; Wang and Schwarz, 2009; Querfurth and LaFerla, 2010; Kopeikina et al., 2012).