MAPT and dementia: Organoids from another five DS donors, and one DupAPP patient, (all diagnosed with clinical dementia) all showed presence of diffuse and compact amyloid-like deposits (Fig. 8) as well as presence of neuritic plaque-like features (focal hyperphosphorylated tau (AT8+), conformationally altered tau (TG3+), and filamentous Tau (AT100+)) within neuropil neurites within plaque-like circular foci (Fig. 9a–n).