The population of CD8+CD45RA+CCR7- T effector memory (TEMRA) cells expands in the peripheral blood of individuals with mild cognitive impairment (MCI) and AD, and in the cerebrospinal fluid (CSF) following infection with Epstein–Barr virus (EBV), suggesting particular CD8+ T cell phenotypes may also play a role in AD9. This evidence concerns the gene CD8A and Alzheimer disease.