As dual-phase amyloid-PET can evaluate amyloid (A) and neurodegeneration (N) with a single tracer injection, dual-phase tau-PET might be able to provide both tau (T) and N. Our study aims to assess the association of early-phase tau-PET scans and 18F-fluorodeoxyglucose (FDG) PET and their comparability in discriminating Alzheimer’s disease (AD) patients and differentiating neurodegenerative patterns. This evidence concerns the gene MAPT and early-onset autosomal dominant Alzheimer disease.