[F-18]-AV-1451 (Flortaucipir) is a novel positron emission tomography (PET) tracer that preferentially binds to paired helical filament (PHF)-tau containing neurofibrillary tangles (NFTs) in Alzheimer’s disease (AD) brains [33, 51] and those that form as a function of age [31, 33]. This evidence concerns the gene MAPT and early-onset autosomal dominant Alzheimer disease.