Amyloid- β and tau deposition influences cognitive and functional decline in Down syndrome.

This study investigates whether tau has (i) an independent effect from amyloid-β on changes in cognitive and functional performance and (ii) a synergistic relationship with amyloid-β in the exacerbation of decline in aging Down syndrome (DS). 105 participants with DS underwent baseline PET [18F]-AV1451 and PET [11C]PiB scans to quantify tau deposition in Braak regions II-VI and the Striatum and amyloid-β status respectively. Linear Mixed Effects models were implemented to assess how tau and amyloid-β deposition are related to change over three time points. Tau was a significant independent predictor of cognitive and functional change. The three-way interaction between time, [11C]PiB status and tau was significant in the models of episodic memory and visuospatial cognition. Baseline tau is a significant predictor of cognitive and functional decline, over and above the effect of amyloid-β status. Results suggest a synergistic relationship between amyloid-β status and tau as predictors of change in memory and visuospatial cognition.