A recent study analyzed tau from both soluble (TBS) and sarkosyl-insoluble (SI) fractions of human frontal cortex across AD, progressive supranuclear palsy (PSP), Pick’s disease (PiD), corticobasal degeneration (CBD), and controls using immunoprecipitation and high-resolution mass spectrometry with isotope-labeled standards [72] (Table 4). Here, MAPT is linked to Alzheimer disease.