Affective Responsivity to Daily Stressors and Cardiac Autonomic Function in Young Adults

• Nora Vallarino, Human Physiology, University of Delaware

• Jody Greaney, Health Behavior and Nutrition Sciences, University of Delaware

Introduction: Heightened emotional responsiveness to daily stressors is linked to elevated cardiovascular disease (CVD) morbidity and mortality, yet the underlying physiological mechanisms remain incompletely understood. In midlife and older adults, greater negative affective responsivity (NA-R) to daily stressors is associated with blunted heart rate variability (HRV), an index of cardiac autonomic dysfunction. Young adults experience more frequent daily stressors and amplified affective responsivity; however, whether this also translates to cardiac autonomic dysfunction [i.e., reduced HRV and cardiovagal baroreflex sensitivity (cvBRS)] in young adults is not known. Similarly, whether and how positive affective responsivity (PA-R) is related to cardiac autonomic function remains unexplored. Hypothesis: We hypothesized that (1) NA-R would be negatively associated with HRV and cvBRS and (2) PA-R would be positively associated with HRV and cvBRS in young adults (18-39 yrs). Methods: Daily stress processes and daily negative and positive affect were assessed during routine life for 8-14 consecutive days in 96 young adults free of traditional CVD risk factors (67 females, 23±6 yrs). On the last day of daily assessments, beat-to-beat blood pressure (finger photoplethysmography) and heart rate (electrocardiogram) were measured during 10-min of supine rest. NA-R and PA-R were operationalized as the intra-individual slope of the change in negative and positive affect, respectively, on stressor days compared to stressor-free days (multilevel modeling). Results: Daily stressors occurred on 37±26% of days (range 0-100%). NA-R was not associated with either HRV (r=0.11, p=0.33) or cvBRS (r=0.072, p=0.52). PA-R was likewise not associated with either HRV (r=-0.040, p=0.72) or cvBRS (r=-0.056, p=0.62). Conclusion: These findings suggest that greater affective responsivity to daily stressors is not associated with cardiac autonomic dysfunction in young adults, perhaps reflecting physiological resiliency to the cardiovascular consequences of daily stress in early adulthood.