MAPT and Alzheimer disease: AD BBMs can be broadly categorized based on their target pathology, including plasma Aβ42/40,4, 5 phosphorylated tau epitopes (p‐tau),6 indicators of neuronal degeneration (e.g., neurofilament light chain),7, 8 and markers of neuroinflammation (e.g., glial fibrillary acidic protein).9