Fig. 4

The interaction and mediation effects of blood neutrophil percentage on brain tau burden. The interaction effect of tau burden on longitudinal sleep-related changes in hippocampal volume was observed in the high neutrophil sample (B1, B2) but not in the pooled (high and low neutrophil) sample (A1, A2). NS adj p > 0.05, *adj p < 0.05. The mediation analysis showed the mediation effects of tau burden, including CSF t-tau (C1–C3) and p-tau (C4–C6), on blood neutrophil percentage within a 2-year follow-up of cognitive outcomes. The blue lines showed the total effect (c), the blue dotted lines showed the direct effect (c′), and the green lines depicted the mediation effects (a*b) of the tau burden. The path weight was expressed as an effect and a p-value