Fig. 3: Mediation model demonstrating the significant indirect effect of BMI in the relationship between ADI and total cortical volume.

Reported values of a, b, and c are regression coefficients for each path. The indirect effect is the product of paths a and b and is described as the amount of mediation attributed to BMI. The dashed line corresponding to c′ indicates the reduced direct effect of ADI on Cortical Volume when BMI is included as a mediator. Inset graphs are from Fig. 1 and are used to illustrate the relationships that must be established to conduct mediation analysis.