Fig 1: Characterization of neuropathology using custom histological scoring and biochemistry. a Representative IHC images from a DS case with Xtau = 1 and XAβ = 1 (UCI 35-06) and from a DS cases with Xtau = 4 and XAβ = 4 (UCI 29-06). FFPE sections were dual stained with primary antibodies specific for either Aβ40/Aβ42 or total Aβ/S262 pTau and were detected using fluorescent secondary antibodies. Scale bars are 100 µm. b Proportions of cases in each cohort with each XAβ and Xtau as determined by custom manual scoring methodology. c–h Protein concentrations determined in frozen tissue, ± SEM. For soluble proteins (APP, sTau), clarified brain homogenate was assayed by ELISA. For insoluble proteins (Aβ40, Aβ42, total insoluble tau, and pTau), formic acid-extracted samples were assayed by HTRF. Significance values were determined by one-way ANOVA with Tukey’s multiple comparisons test. *: 0.01 < p ≤ 0.05; **: 0.001 < p ≤ 0.01, ***: 0.0001 < p ≤ 0.001. ****: p < 0.0001