Neurofibrillary tangles and neuropil threads (NTs) are the major neuropathological hallmarks of Alzheimer's Disease (AD). They are composed of the microtubule-associated protein tau that has undergone posttranslational modifications, including phosphorylation, deamidation and isomerization on asparaginyl or aspartyl residues. They originate by the aggregation of hyper-phosphorylated protein tau and its conformers. AD shares this pathology with many neurodegenerative tauopathies, in particularly with specified types of frontotemporal dementia (FTD).