Meyer PF, et al. - Researchers sought to define individuals with tau abnormality indicated by cerebrospinal fluid (CSF) assay or PET. They included 322 individuals in the Alzheimer’s Disease Neuroimaging Initiative who underwent CSF and PET assessments of tau pathology between 2010 and 2019. They recruited a sum of 322 study individuals. They matched tau-positive vs tau-negative groups as shown by either modality, demographic and clinical variables, amyloid β–PET burden, and flortaucipir-PET binding across Braak stage-related ROIs. They further compared 5-year rates of CSF P-tau accumulation and cognitive decline before flortaucipir-PET scanning. The results indicated that suprathreshold CSF P-tau without flortaucipir-PET abnormality may show a stage of AD development characterized by early tau abnormality without measurable loss in cognitive performance. It was noted that elevation of CSF P-tau seems to precede flortaucipir-PET positivity in the progression of AD pathogenesis and related cognitive decline.