Cardiovascular Reactivity and Cardiovascular Disease Risk in Adolescents
Lambiase, Maya Jung
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Background. Greater cardiovascular reactivity to psychological stress is associated with carotid artery intima-media thickness (CIMT) and a greater risk for cardiovascular disease (CVD) as early as childhood. Cardiovascular responses during exercise are matched to the increased metabolic demand, but this may not be the case during psychological stress. It is hypothesized that cardiovascular responses during acute psychological stress are in excess of what is expected based on metabolic demand, and this excess cardiovascular response may promote atherogenesis. However, this has not yet been tested. Purpose. To determine whether acute psychological stress results in excess cardiovascular responses relative to concurrent levels of metabolic demand in adolescents and to determine whether this excess was associated with CIMT. Methods. Fifty-four adolescents, ages 13-16 years completed a graded exercise test on one day and measures of psychological stress reactivity (star tracing, speech) on another day. Heart rate (HR), blood pressure (BP), and oxygen (O2) consumption were measured on both days. On a third visit adolescents completed an ultrasound scan to measure CIMT. Results. Predicted HR and BP values during psychological stress were calculated based on HR-O 2 and BP-O 2 relationships calculated during graded exercise. At a given O 2 consumption, actual HR and BP were greater than predicted values during the psychological stress tasks. Traditionally measured systolic blood pressure reactivity (SBP) (β=0.001, p<0.04) and excess SBP (β=0.001, p<0.04) during the speech task were associated with greater CIMT. When excess SBP was tested as a mediator in the regression model, traditionally measured SBP reactivity remained a significant predictor of CIMT. Conclusions. This study replicated the results in adults that cardiovascular responses were in excess of what was predicted based on metabolic demand in adolescents and adds to the growing body of literature showing a link between traditionally measured SBP reactivity to acute psychological stress and CIMT in youth. The results further add to the literature by demonstrating that excess SBP is also associated with CIMT. That excess SBP did not mediate the relationship between SBP reactivity and CIMT raises doubts about whether the metabolic appropriateness of cardiovascular responses during psychological stress is a contributing factor to CVD risk.