MAPT and Alzheimer disease: Using linear models, we tested biomarker changes as predictors of cognitive changes, comparing predictive strengths across biomarkers using bootstrapping.<h4>Results</h4>Tau-PET, plasma p-tau217, and cortical thickness changes accurately tracked change rates in Mini-Mental State Examination, Alzheimer's Disease Assessment Scale-Cognitive Subscale 13-item version, Clinical Dementia Rating-Sum of Boxes, and Preclinial Alzheimer Cognitive Composite scores.