Sex influences the effect of adiposity on arterial stiffness and renin-angiotensin aldosterone system activity in young adults

Introduction Sex influences the cardiovascular risk associated with body mass index (BMI) in older adults. Whether this risk differs by sex in younger adults is unknown. We aimed to evaluate the association between measures of adiposity and arterial stiffness and reninangiotensin-aldosterone system (RAAS) activity in younger adults, stratified by sex. Methods Body mass index (BMI), waist circumference (WC), hip circumference (HC), waist-to-hip ratio (WHR), waist-to-height ratio (WHtR) and fat mass% (FM%) were measured in healthy participants in a fasting, high-salt state. Arterial stiffness [pulse wave velocity (PWV) and aortic augmentation index (AIx)] were measured at baseline and in response to angiotensin II challenge, a validated marker of RAAS activity. Associations were evaluated using linear regression analysis and stratified by sex. Results Ninety-five healthy, normotensive, non-diabetic females (n = 67, 37 +/- 2 y, BMI 25 +/- 1 kg/m(2)) and males (n = 28, 39 +/- 3 y, BMI 27 +/- 1 kg/m(2)) participated in the study. No association was observed between any measure of adiposity and PWV, either at baseline or in response to angiotensin II challenge in premenopausal females. In contrast, all measures of adiposity except HC were associated with PWV at baseline (BMI r = 0.32; WC r = 0.18; WHtR r = 0.34; FM r = 0.21; all values p < .05) and in response to AngII (BMI r = -0.39; WC r = -0.42; WHR r = -0.39; and WHtR r = -0.55) in males. Most adiposity measures were positively associated with baseline AIx (BMI r = 0.33; WC r = 0.27; WHtR r = 0.35; FM% r = 0.25; p < .05) in females, while only WHtR was associated with baseline AIx (r = 0.39; p = .04) in males. All measures of adiposity were positively associated with a blunted Aix response to Ang II (all values p < .001) in females. BMI, WC, WHR and WHtR were associated with a blunted AIx response to Ang II (Delta AIx: BMI r = -0.37; WC r = -0.31; WHR r = -0.16; and WHtR r = -0.22; all values p < .05) in males. Conclusion The associations between adiposity measures and cardiovascular risk differ by sex in a young population. These factors should be considered when managing cardiovascular risk.