Including CSF Aβ42 as a second predictor increased the explained CSF sTREM2 level variability (R = 0.61), while age and delirium did not further increase predictive ability (ln(CSF sTREM2): CSF p-tau β1 = 0.01, p < 0.001; CSF Aβ42 β2 = 0.002, p = 0.002; age β3 = 0.0001, p = 0.91; delirium β4 = − 0.03, p = 0.86; n = 59). Here, MAPT is linked to delirium.