MAPT and early-onset autosomal dominant Alzheimer disease: Aβ and tau pathologies exert synergistic effects on neuronal morphology/function (Rhein et al., 2009) particularly at synapses (Hoover et al., 2010; Ittner et al., 2010; Takahashi et al., 2010; Amadoro et al., 2012) believed to initiate Alzheimer’s disease progression (Selkoe, 2002), indicating that passive immunization with 12A12mAb can contribute to improve disease-associated mnestic disabilities at its early phases by preventing both pathognomonic toxic proteins from damaging synaptic connectivity in pathologically relevant vulnerable neuronal circuits.