Role of tau deposition in early cognitive decline in Down syndrome

Drawing on the amyloid/tau/neurodegeneration (AT[N]) model, the study examined whether the tau positron emission tomography (PET) biomarker [¹⁸F]AV-1451 was associated with episodic memory problems beyond what was predicted by the amyloid beta (Aβ) PET in Down syndrome (DS).

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+).

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.

Similar to late-onset and autosomal dominant Alzheimer's disease (AD), high tau was an indicator of early prodromal AD in DS.