NPPB and Anxiety: While the direct effect of NT-proBNP on HADS anxiety at baseline was not significant (B = -0.288; CI: -1.1095; 0.5334), we found that the relationship between NT-proBNP and HADS anxiety at baseline was mediated by social support with an indirect effect of -0.477 (CI − 0.8770; − 0.1087) (Fig. 2), which got weaker but stayed significant when controlled for age (B = − 0.468; CI − 0.9196; − 0.0488).