UC Irvine

This dissertation investigates the relationship between resting heart rate variability (HRV) and substance use, including the potential moderating roles of gender and race. Study 1 analyzes data from the Midlife in the United States Study (MIDUS) to examine cross-sectional associations between resting HRV and substance use, exploring potential gender differences and mediation effects involving emotion regulation (ER). Results indicate that men reported higher emotion control, alcohol consumption, and cigarette smoking compared to women. Higher resting HRV was associated with increased alcohol consumption, particularly in women, while no significant link was found between resting HRV and cigarette smoking. Mediation and moderation models did not yield significant findings. Study 2 utilizes data from the Augusta Heart Study to examine associations between resting HRV in late adolescence and substance use in early adulthood, again while considering gender and race. Results show that men and European Americans used more substances than women and African Americans, respectively. However, resting HRV did not predict substance use. Among African Americans, the slope between resting HRV and cigarette smoking was more positive in women than in men. These findings suggest that resting HRV may not be a particularly strong predictor of substance use but could still hold relevance in specific contexts or subgroups. Further research is needed to explore the complex interplay of factors influencing substance use behaviors. This dissertation highlights the importance of understanding various motivations for substance use and emphasizes the need for ongoing research targeting individualized treatments based on marginalized identities.