MAPT and Alzheimer disease: To assess the relationship of CSF EV Aβ42 and CSF EV Tau/Aβ42 ratio to memory impairment (a hallmark of early aMCI/AD) versus cognitive domains more characteristic of HAND, 55 HIV+ individuals with available CSF EV Aβ42 and CSF EV Tau/Aβ42 ratio values were categorized in groups by CSF EV Aβ42 top/middle vs. bottom tertiles or CSF EV Tau/Aβ42 ratio bottom/middle vs. top tertiles.