MAPT and Alzheimer disease: Given that longitudinal follow-up of neuropathologically defined PART is not possible, a main controversy exists whether PART reflects an early form of AD, with Aβ pathology developing in the further disease course, or whether it represents an entirely distinct pathologic entity.12,13,14 Herein, we noted that A− TMTL+ individuals did not show significant Aβ accumulation over the available follow-up period, thus arguing against the possibility that this condition reflects an early tau-first subtype of AD.55