Interestingly, associations between microglial markers in the grey and white matter highlighted (i) Iba1 associated with control groups independently of systemic infection, maybe reflecting microglial motility, a function essential to healthy brain [44, 47]; (ii) CD68 (phagocytosis) and CCR2 (monocyte recruitment) as markers of neurodegeneration in AD independently of systemic infection; and (iii) CD64 as a potential marker of systemic infection whatever the disease status [44]. This evidence concerns the gene CCR2 and Alzheimer disease.