Role of tau deposition in early cognitive decline in Down syndrome

INTRODUCTION: Drawing on the amyloid/tau/neurodegeneration (AT[N]) model, the study examined whether the tau positron emission tomography (PET) biomarker [(18)F]AV‐1451 was associated with episodic memory problems beyond what was predicted by the amyloid beta (Aβ) PET in Down syndrome (DS). METHODS: Data from 123 non‐demented adults with DS (M = 47 years, standard deviation = 6.34) were analyzed. The Cued Recall Test assessed episodic memory. Tau PET standardized update value ratio (SUVR) was assessed across Braak regions as continuous and binary (high tau [T(H)] vs. low tau [T(L)]) variable. Global PET Aβ SUVR was assessed as binary variable (Aβ– vs. Aβ+). RESULTS: In models adjusting for controls, tau SUVR was negatively associated with episodic memory performance in the Aβ+ but not Aβ– group. The Aβ+/T(H) group evidenced significantly worse episodic memory than the Aβ+/T(L) group. DISCUSSION: Similar to late‐onset and autosomal dominant Alzheimer's disease (AD), high tau was an indicator of early prodromal AD in DS.