MAPT and Alzheimer disease: In this Alzheimer's Association Global Biomarker Standardization Consortium (GBSC) plasma p‐tau Round Robin study, we performed a comprehensive and blinded comparison of 33 different p‐tau assays, including seven different p‐tau epitopes, or p‐tau/t‐tau ratios, utilizing eight immunological platforms, in plasma and CSF from symptomatic individuals categorized as having AD or non‐AD pathology.