Abstract Body: Background: Stress, stress perceptions, appraisals and perceived individual ability to manage stress significantly impact cardiovascular health in humans, yet this relationship is complex and multi-factorial. The Stress Overload Scale (SOS) and its sub-domains Event Load (EL) and Personal Vulnerability (PV) may identify individuals at a higher risk for stress-related cardiovascular health concerns. Yet whether the cardiovascular reactivity patterns, autonomic tone and cardiovascular risk differ based on these self-reported stress-subdomains are unknown. We investigated the relationship between SOS and its subscales with acute stress-induced cardiovascular reactivity markers and resting markers of autonomic tone.
Methods: In 610 South Africans (46% Men, 45% Black African, 20-30 years) the SOS and subscales EL and PV, assessed stress overload. We determined those with a total SOS score, and combinations High-EL-High-PV; Low-EL-low-PV; Low-EL-High-PV and High-EL-Low-PV, using established sub-domain cut-points for the SOS scale. An acute mental stress task was administered for 1-minute and hemodynamic reactivity for systolic-and diastolic BP, heart rate (HR), stroke volume (SV), cardiac output (CO), total peripheral resistance (TPR), arterial compliance (Cwk) and left-ventricular ejection fraction (LVEF) were measured. Ambulatory BP and heart rate variability (HRV) was assessed.
Results: Of the 610 participants, 25% (n=151) were High-EL-High-PV; 27% (n=163) Low-EL-Low-PV; 29% (n=174) Low-EL-High-PV and 19% (n=122) High-EL-Low-PV. Within each group, sex and ethnicity did not differ significantly. Depressed HRV was the highest in the high-EL-high-PV group (P<0.01), with the low-EL-high-PV also indicating depressed-HRV compared to the low-PV groups (all P<0.02). High-EL-low-PV had greater acute hemodynamic reactivity compared to the other groups (all P<0.05). In the two high-PV groups, increases in CO, TPR and decreases in CwK associated with PV (all P<0.03). In the High-EV-Low-PV group, increases in CO, HR, SV and Cwk and decreases in TPR associated inversely with PV (P<0.001) and positively with EL (P=0.014).
Conclusion: Perceived personal vulnerability consistently associated with autonomic tone and acute hemodynamics, with greater PV adversely impacting acute hemodynamics, and possibly future cardiovascular risk. However, a low PV, despite a high EL, is linked to compensatory, physiologically advantageous autonomic tone and acute hemodynamic stress responses.