APOE and Alzheimer disease: There were weak to moderate correlations between apoE3 and apoE4 isoform concentrations and AD biomarkers (Aβ42/40, t-tau, p-tau) for all individuals (rho = − 0.14–0.41, p < 0.001) (Additional file 8: Figure S7A) as well as for the Aβ+ (rho = − 0.15–0.44, p < 0.001) and Aβ− groups (rho = − 0.21–0.59, p < 0.01) (Additional file 8: Figure S7B-C).