We hypothesize that the increased neuroinflammation was observed in AD injected 5XFAD mice and not in CTL 5XFAD mice or in AD injected WT mice because of a combined effect of the presence of PHF-tau proteins in the injected material and of the disruption of the blood–brain barrier in 5XFAD mice as we confirmed by demonstrating an extravasation of immunoglobulins in the latter mice, implying potentially a more easy access of intravenously injected PHF-tau proteins to the brain tissue in 5XFAD mice. This evidence concerns the gene MAPT and Alzheimer disease.