APP and Alzheimer disease: Furthermore, reduced uptake of IgG, anti-BACE1, and anti-TfR/BACE1 antibodies was observed in the brains of PS2-APP, P301L, and P301S AD model mice, in contrast to the high CNS uptake of these molecules in the experimental model of allergic encephalomyelitis, which causes massive damage to the BBB, suggesting that no or minimal BBB impairment occurs in AD [43].