Early drug use might to lead to drug addiction; the earlier individuals begin to engage in risky drug use, the more likely they are to engage in later drug abuse. Therefore, early intervention is warranted. This study explored individual differences in drug use tendencies in young and healthy adults. Specifically, I examined how self-reported emotion regulation (ER) difficulties and inhibition abilities, as indexed by resting heart rate variability (HRV), might predict risky drug use tendencies in young adults. I further considered these associations stratified by women and men. Novel results showed self-reported (or perceptions of) difficulties in ER were associated with higher drug usage in the full sample and this association was significantly stronger in women than men. Among the six different facets of ER difficulties, only those related to impulse control difficulties and limited access to ER strategies were most related to risky drug usage in women but not men. The other four facets of ER difficulties were not significantly different between men and women. An indirect association was found between resting HRV and drug use, mediated by self-reported difficulties in ER, particularly in women. Overall, results indicate that lower HRV and difficulties in ER indirectly and directly, respectively, predict risky drug use in women. These data are in line with research suggesting women might engage in risky drug use primarily for stress regulation while men might engage in risky drug activity irrespective of both resting HRV and difficulties in ER. Clinical implications are discussed.

Higher self-reported rumination, a common form of trait perseverative cognition, is linked with lower resting heart rate variability (HRV), which indicates poorer cardiac function and greater disease risk. A prior meta-analysis and systematic review indicates that in samples with fewer European Americans, the association of rumination with both heart rate and blood pressure was stronger. Thus, trait rumination may be more strongly associated with HRV among ethnically minoritized populations, but few studies exist. The current study therefore investigated whether differences in the association of self-reported rumination with resting HRV varied by ethnicity in a sample (N = 513; Mage = 19.41; 226 Women) of self-identified African Americans (n = 110), Asian Americans (n = 84), and European Americans (n = 319). Participants completed a 5-min baseline period to assess resting HRV, followed by the Ruminative Responses Scale, which contains three facets of rumination including brooding, depressive, and reflective rumination. On average, Asian Americans reported higher levels of rumination relative to European Americans. African Americans had higher average HRV than Asian Americans. Adjusting for covariates, higher self-reported rumination was significantly associated with lower HRV in both African and Asian Americans, but not significantly so in European Americans. This finding was consistent for brooding and reflective, but not depressive rumination. Overall, this study lends insight into a psychological mechanism – rumination – that may impact health disparities among ethnically minoritized individuals, contributing to an understanding of how stress gets under the skin among such populations.

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.

Rationale

Objective

Methods

Results

Conclusions