We detected that the possession of an APOE ε2 allele, known to be associated with reduced risk of Alzheimer’s disease, was significantly related to a high expression of Iba1 (P = 0.001) and MSR-A (P < 0.001) and a reduced amount of CD68 and HLA-DR (P < 0.001, respectively), whereas possession of an APOE ε4 allele, known to be associated with increased risk of Alzheimer’s disease, was significantly related to greater expression of CD68, HLA-DR and CD64, but a reduced amount of Iba1 (P < 0.001, respectively). This evidence concerns the gene CD68 and early-onset autosomal dominant Alzheimer disease.