GRIN1 and Alzheimer disease: Studies that have evaluated NMDAR subunit expression using RT-qPCR report reduced mRNA levels of GluN1, GluN2A, and GluN2B in the hippocampus, temporal cortex, entorhinal cortex, and cingulate cortex from individuals with AD and report no alterations in less vulnerable regions, such as the occipital cortex or cerebellum [132,137,138,139].