Here we evaluated whether regional patterns of baseline tau-PET predict prospective longitudinal decline in specific cognitive domains in early symptomatic Alzheimer's disease (AD), including participants from clinical trial cohorts.<h4>Methods</h4>731 amyloid-positive participants with a clinical diagnosis of mild cognitive impairment (MCI) or mild AD dementia underwent a flortaucipir F 18 PET (FTP-PET), structural MRI, and neuropsychological testing with the AD Assessment Scale-Cognitive Subscale (ADAS-Cog). Here, MAPT is linked to early-onset autosomal dominant Alzheimer disease.