To achieve this, we analyzed data from 592 subjects ranging from cognitively normal to dementia from the Alzheimer’s Disease Neuroimaging Initiative (ADNI), with available cross-sectional amyloid-PET and tau-PET data to assess fibrillar Aβ and tau pathology, as well as CSF-based αSyn SAA data to identify αSyn pathology. Here, MAPT is linked to early-onset autosomal dominant Alzheimer disease.