Furthermore, across the whole disease spectrum including NC, MCI and AD subjects (n = 310), lower CSF-decorin levels correlated to higher CSF-t-tau (beta(se) = − 0.11(0.04), p = 0.0014) (Additional file 9: Fig. S2b) and CSF-p-tau levels (beta(se) = − 0.16(0.04), p < 0.0001) (Additional file 9: Fig. S2c) but no association with CSF-Aβ42 levels was observed (beta(se) = 0.09(0.06); p = 0.11) (Additional file 9: Fig. S2a) which is expected considering that decorin increases early in the a + t − preclinical AD subjects and then subsequently decreases upon disease progression (Fig. 4e). This evidence concerns the gene DCN and Alzheimer disease.