Partial effects plots for DHEAS showing the smooth of DHEAS concentrations on age for females (a, n = 31, edf = 5.81, p < .001) and males (b, n = 22, edf = 7.03, p < .001), and the partial parametric effect of sex on DHEAS (c, −1.17, p = .40). Overall comparison of DHEAS concentrations between males and females also shown for reference (d). DHEAS, dehydroepiandrosterone-sulfate