MAPT and tauopathy: In the 2018 NIA-AA Research Framework, PET (and other biomarkers) was used to classify each individual as positive or negative for brain amyloidosis (“A,” e.g., with amyloid PET), tauopathy (“T,” e.g., with tau PET), and neurodegeneration (“N,” e.g., with FDG PET) by using the AT(N) framework (17).