GRIA4 and Alzheimer disease: While CSF GluA4 levels were not associated with clinical diagnosis (Fig. 2a; p = 0.2), low NPTX2 levels correlated with low GluA4 levels in controls (n = 27 r2 = 0.2, p = 0.003), sAD (n = 20, r2 = 0.4, p < 0.0001) and in DS (n = 81, r2 = 0.4, p < 0.0001): The association in DS was apparent at all AD stages; aDS (n = 36, r2 = 0.5, p = 0.04), pDS (n = 18, r2 = 0.5, p = 0.005) and dDS (n = 21, r2 = 0.4, p = 0.02).