In this era of intensive shift to blood-based assays, it is crucial to investigate the fine-grain balance between the serum and CSF concentration of AD-specific biomarkers, such as t-tau, p-tau, Aβ42, Aβ40, and the Aβ42/40 ratio, but also to understand if their relationship with other molecules such as albumin may indirectly play a role. Here, MAPT is linked to Alzheimer disease.