In human post-mortem sections of the temporal neocortex, no differences were detected in microglial activation between APOE4 carriers and non-carriers [151]; however, studies in living individuals across the aging and AD spectrum [152], as well as studies in mice and with the use of transcriptomics [92,153,154,155,156], have demonstrated the important contribution of the APOE4 allele to the microglial response in AD. Here, APOE is linked to Alzheimer disease.