Interestingly, even though exosomal Tau represents a minimal fraction of total extracellular Tau, exosomes derived from the condition media obtained from cultured neuroblastoma cells (N2a), or from the CSF of early AD patients contain significantly higher levels of phosphorylated (but not total) Tau compared to age-matched healthy subjects, although some controversies exist [91]. Here, MAPT is linked to Alzheimer disease.