MAPT and Alzheimer disease: AD is associated with progressive accumulation of two hallmarks, namely extracellular Amyloid β (Aβ) plaques and intracellular neurofibrillary tangles (NFTs; Selkoe, 2001; Duyckaerts et al., 2009) Currently there are no indications of increased Aβ and tau protein production in AD which suggests that the accumulation of these proteins is caused by a lack of cellular clearance (Olsson et al., 2003).