Tauopathies are diseases associated with the intracellular pathological aggregation of tau protein in neurofibrillary tangles, which is observed in almost 26 neurodegenerative diseases, including Alzheimer's disease, progressive supranuclear palsy (PSP), Dementia Pugilistica, and Pick's disease. This evidence concerns the gene MAPT and early-onset autosomal dominant Alzheimer disease.