The strong similarity in induction of Tau-pathology by prion-like Tau-seeds and pre-aggregated forms of Aβ in in vivo models (i.e. in crosses of transgenic mice, following injection of pre-aggregated Aβ containing brain extracts from mice and AD patients, and pre-aggregated synthetic Aβ) has incited us to analyze whether pre-aggregated Aβ could directly cross-seed filamentous Tau-aggregation, leading to propagation of Tau pathology. Here, MAPT is linked to Alzheimer disease.