SHBG and Alzheimer disease: The results of the network MR analysis indicated that testosterone may act as a mediator in the causal pathway of SHBG on AD, and accounts for 6.2% of the overall impact of SHBG on AD (the effect of SHBG on testosterone is 0.062, the effect of testosterone on AD is 0.005, so the mediating effect of testosterone is equal to 0.062 × 0.005 = 0.00031, the mediated proportion was the mediating effect of testosterone/the total effect of SHBG on AD = 0.00031/0.005 = 6.2%) (see Table 6).