MAPT and frontotemporal dementia: Our analyses, carried out in a well-characterized cohort of patients with FTD, provide evidence that ApoE4 genotype accelerates neurodegeneration in patients with MAPT mutations or FTLD-tau pathology independent of Aβ—notably AAO in FTD-tau cases was on average about 3.9 years earlier in those who carried an ApoE4 allele.