MAPT and Cognitive impairment: Recent PET-to-autopsy studies [217–219] have consistently reported elevated Flortaucipir-PET signal in patients with advanced AD tau pathology (usually Braak stages IV or V), and the FDA recently approved Flortaucipir for the estimation of aggregated tau neurofibrillary tangles in adult patients with cognitive impairment who are being evaluated for AD [220].