Fig. 5
Mediation effects of brain volume on the association between grip strength and behavioral outcomes. a Mediation effect of mean GMV on the association between grip strength and behavioral outcomes. The proportion of variance explained by the mediation as well as the lower and upper bound of 95% confidence interval was shown. b The top three behavioral phenotypes having the highest mediation effect size were numeric memory (proportion mediated = 21.83%; 95% CI = 13.80%~41.88%; bootstrapping test, FDR corrected P < 2 × 10−4), symbol-digit substitution: attempted (15.58%; 9.66%~29.87%; P < 2 × 10−4), and symbol-digit substitution: corrected (15.26%; 9.31%~29.51%; P < 2 × 10−4). a×b: the indirect effect; c: the total effect; c’: the direct effect