MAPT and early-onset autosomal dominant Alzheimer disease: Lastly, it is important to mention the possibility that the observed tau-PET signal may partially reflect non-tau related processes (e.g. astrogliosis, iron accumulation, spill-in from off-target regions), given the suboptimal binding properties of [18F]flortaucipir to non-Alzheimer’s disease tau pathology.67,68