MAPT and Alzheimer disease: Protein aggregates are one of the pathological features of several proteopathic neurodegenerative diseases,[1, 2, 3, 4] including Alzheimer's disease (AD), and a diversity of synthetic fluorescent ligands that can be used for optical imaging of these proteinaceous aggregated species has been presented.[5, 6, 7, 8, 9, 10, 11, 12, 13, 14] In AD, the two main neuropathologic lesions resulting from protein aggregation, i. e., the plaques and the neurofibrillary tangles, are respectively composed of the amyloid‐β (Aβ) peptide and the tau protein.