MAPT and early-onset autosomal dominant Alzheimer disease: The study found that tau spreads into the posterior cingulate cortex (PCC) via the cingulum bundle, a major white matter tract that connects the hippocampus with the cingulate gyrus.11 The results of this study suggest that Aβ-associated tau accumulation is accelerated by the apolipoprotein E (APOE ε4) allele, the most significant risk factor of sporadic late-onset Alzheimer's disease, even at lower levels of Aβ, indicating that APOE ε4 may promote earlier Aβ-driven tau propagation across interconnected brain regions.