A and B: linear regression analysis demonstrating the relationships between age and baseline middle cerebral artery velocity (MCAv; A) and cerebrovascular resistance index (CVRi; B; n = 73, females = 39). Solid line represents the regression fit for males, and dotted line represents the regression fit for female participants. Hierarchical regression models (P value and R2) are presented for the relationship with age (model 1), the relationship with sex (model 2), and the moderator relationship of the sex-dependent relationship with age (model 3). Slope coefficients (β) of the relationship with age are presented for males and females separately (model 3). MCAv, middle cerebral artery velocity.