MAPT and Alzheimer disease: In AD, sEVs derived from cerebrospinal fluid (CSF) and plasma exhibit increased levels of amyloid-β (Aβ) peptides, phosphorylated tau (p-tau), and regulatory microRNAs such as miR-29a/b and miR-34a, which are implicated in amyloid genesis and synaptic dysfunction [28,57,58].