Racial differences in baroreflex function: Implications for the cardiovascular conundrum.

Study objective: African Americans (AAs) show early signs of vascular dysfunction paired with elevated blood pressure (BP) and total peripheral resistance (TPR), which is thought to underlie their increased rates of cardiovascular health complications relative to European Americans (EAs). AAs paradoxically have higher cardiac vagal tone, indexed by heart rate variability (HRV), which is cardio-protective. This paradox has been termed the Cardiovascular Conundrum. The physiological mechanism underlying this phenomenon is not well understood. We examined race differences in baroreflex function, which might be an important mechanism underlying the Cardiovascular Conundrum. Design: Participants completed a 5-minute baseline period where resting cardiac metrics were assessed. Setting: Laboratory. Participants: 130 college-aged individuals (54 women, 57 AAs). Main outcome measures: Baroreflex function was indexed as baroreflex sensitivity (BRS; the magnitude of changes in cardiovascular activity in accordance with BP changes) and effectiveness (BEI; the ratio of BP changes that elicit changes in cardiovascular activity) in the cardiac, vascular, and myocardial limbs. Results and conclusions: Results showed AAs to have higher HRV and cardiac BRS in comparison to EAs, suggesting the baroreflex is more sensitive to correcting the heart period for changes in BP among AAs compared to EAs. However, AAs showed lower vascular BEI relative to EAs, suggesting less effective control of TPR. In sum, lower BEI in the vascular branch might be an important mechanism underlying the Cardiovascular Conundrum (i.e., higher HRV and BP) and by extension, health disparities in cardiovascular diseases between AAs and EAs.

Negative emotions enhance memory-guided attention in a visual search task by increasing frontoparietal, insular, and parahippocampal cortical activity.

Previous literature demonstrated that long-term memory representations guide spatial attention during visual search in real-world pictures. However, it is currently unknown whether memory-guided visual search is affected by the emotional content of the picture. During functional magnetic resonance imaging (fMRI), participants were asked to encode the position of high-contrast targets embedded in emotional (negative or positive) or neutral pictures. At retrieval, they performed a visual search for targets presented at the same location as during encoding, but at a much lower contrast. Behaviorally, participants detected more accurately targets presented in negative pictures compared to those in positive or neutral pictures. They were also faster in detecting targets presented at encoding in emotional (negative or positive) pictures than in neutral pictures, or targets not presented during encoding (i.e., memory-guided attention effect). At the neural level, we found increased activation in a large circuit of regions involving the dorsal and ventral frontoparietal cortex, insular and parahippocampal cortex, selectively during the detection of targets presented in negative pictures during encoding. We propose that these regions might form an integrated neural circuit recruited to select and process previously encoded target locations (i.e., memory-guided attention sustained by the frontoparietal cortex) embedded in emotional contexts (i.e., emotional contexts recollection supported by the parahippocampal cortex and emotional monitoring supported by the insular cortex). Ultimately, these findings reveal that negative emotions can enhance memory-guided visual search performance by increasing neural activity in a large-scale brain circuit, contributing to disentangle the complex relationship between emotion, attention, and memory.

Multi-ethnic variation in the ties that bind rumination and heart rate variability: Implications for health disparities.

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 meta-analysis and systematic review indicated 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 resting HRV among ethnically minoritized populations. The current study 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 five-minute 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 resting HRV than Asian Americans. Adjusting for covariates, higher self-reported rumination was significantly associated with lower resting 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 minoritized populations.

Attachment insecurity, heart rate variability, and perceived social support in a diverse sample of young adults.

Psychological and physical factors are robustly associated with perceived social support. Drawing from the literature on attachment style in adults and psychophysiology, we examined the possibility that the interaction of attachment insecurity and resting heart rate variability (HRV) was associated with perceived social support in a diverse sample of young adults living in the U.S (N = 145, Mage = 20.45) that was majority Latino (n = 77). Analyses revealed three key findings. First, in the overall sample, attachment avoidance and attachment anxiety were negatively associated with perceived social support, but in the Latino sample, only attachment avoidance was negatively associated with perceived social support. Second, HRV was not associated with perceived social support in the overall sample nor in the Latino sample. Third, attachment insecurity and HRV interacted to predict perceived social support only in the Latino sample such that, for those with lower levels of HRV, attachment anxiety was positively associated with perceived social support. This study underscores the importance of examining both psychological and physiological processes with careful consideration of ethnicity/culture in order to better understand perceived social support.

Resting heart rate variability and emotion regulation difficulties: Comparing Asian Americans and European Americans.

Asian Americans and European Americans differ in emotion regulation (ER), particularly regarding strategies utilized to adaptively engage in ER. Resting heart rate variability (HRV), a biomarker of ER ability, is suggested to differ between Asian Americans and European Americans, but evidence for such differences has been inconsistent. Yet, research has not considered how Asian Americans and European Americans might differ in the well-established link between resting HRV and ER difficulties, which might lend a better understanding of such inconsistencies. In 374 college-aged individuals (66 Asian Americans; 311 European Americans; 190 women; mean age = 19.3 years [Min. 18, Max 38]), we examined if ethnicity moderated the link between resting HRV and self-reported ER difficulties. Resting HRV was obtained during a 5-min resting-baseline period, and ER difficulties were assessed using the Difficulties in ER Scale, which contained six facets of ER difficulties. Adjusting for gender and body mass index, moderation analyses showed a stronger association between resting HRV and ER difficulties in Asian Americans compared to European Americans. When examining facets of ER, ethnicity moderated only the link between resting HRV and difficulties in accessing ER strategies when facing negative emotions. At lower levels of HRV, Asian Americans reported greater difficulties in ER relative to European Americans. This effect diminished and trended in the opposite direction among those with higher HRV. In sum, these results provide novel evidence that higher resting HRV might be particularly important for adaptive ER among Asian Americans - a marginalized ethnic group - in the U.S.

Differential Associations of Childhood Abuse and Neglect With Adult Autonomic Regulation and Mood-Related Pathology.

OBJECTIVE: This study assessed whether different types of childhood maltreatment (i.e., abuse versus neglect) had differential relationships with heart rate variability (HRV) and baroreflex sensitivity. In addition, this study tested the indirect effect of maltreatment subtypes on adult mood-related psychopathology via HRV, and whether these relationships differed in those with HRV above and below established clinical cutoffs. METHODS: Secondary analysis was performed using the Midlife Development in the United States data set ( N = 967; Mage = 55; 58.4% female; 75.9% White). In a single study visit, autonomic measurements were captured at rest, during two cognitive stressors (Stroop and MATH tasks), and during recovery after the tasks. Structural equation modeling was used to assess the relationships between key variables during all three measurement periods. RESULTS: Resting pathways from abuse and neglect to baroreflex sensitivity were nonsignificant, as was the pathway from HRV to mood-related pathology. Notably, greater abuse was significantly predictive of lower HRV (standardized ß = -0.42, p = .009), whereas greater neglect was significantly predictive of higher HRV (standardized ß = 0.32, p = .034). In addition, higher abuse was significantly predictive of greater adult symptoms (standardized ß = 0.39, p < .001), but neglect was not found to be related to adult mood-related pathology. Significant relationships between variables were only found in those with low HRV. CONCLUSIONS: Although cross-sectional, our findings provide further evidence that low HRV may be a transdiagnostic endophenotype for mood-related pathology and suggest that greater differentiation between abuse and neglect is appropriate when investigating the impact of childhood maltreatment on adult health outcomes.

Sex differences in heart rate and heart rate variability in rats: Implications for translational research.

The present study aimed to investigate sex differences in measures of cardiac chronotropy and heart rate variability (HRV) in 132 young adult wild-type Groningen rats (n = 45 females). Electrocardiographic signals were recorded for 48 h in freely moving rats to quantify heart rate (HR) and inter-beat interval (IBI) as measures of cardiac chronotropy, and time- and frequency-domain HRV parameters as physiological readouts of cardiac vagal modulation. Females showed greater vagally-mediated HRV despite having higher HR and shorter IBI than males during undisturbed conditions. Such differences were evident i) at any given level of HRV, and ii) both during the 12-h light/inactive and 12-h dark/active phase of the daily cycle. These findings replicate the paradoxical cardiac chronotropic control reported by human meta-analytic findings, since one would expect greater vagally-mediated HRV to be associated with lower HR and longer IBI. Lastly, the association between some HRV measures and HR was stronger in female than male rats. Overall, the current study in young adult rats provides data illustrating a sex-dependent association between vagally-mediated HRV and indexes of cardiac chronotropy. The current results i) are in line with human findings, ii) suggest to always consider biological sex in the analysis and interpretation of HRV data in rats, and iii) warrant the use of rats for investigating the neuro-hormonal basis and temporal evolution of the impact of sex on the association between vagally-mediated HRV and cardiac chronotropy, which could inform the human condition.

Heart rate variability in the prediction of mortality: A systematic review and meta-analysis of healthy and patient populations.

Measures of heart rate variability (HRV) as a predictor of risk of disease and mortality have been investigated from various perspectives for more than six decades. The aim of the present comprehensive meta-analysis is to examine eight different HRV parameters to determine their association with all-cause and cardiac mortality. A total of 32 studies and two individual participant datasets (IPD) with 37 samples and 38,008 participants were included. Lower HRV parameter values were significant predictors of higher mortality across different ages, sex, continents, populations and recording lengths. Most of the examined parameters showed comparable hazard ratios (HR). IPD sub-analysis for heart rate corrected HRV parameters confirmed the strong association between HRV and all-cause mortality. Meta-regressions revealed no effect modifier for HRs extracted from covariate-adjusted studies. Sub-analyses of studies comparing the lowest quartile of 5-min root mean square of successive differences (RMSSD) vs. the other quartiles yielded a combined HR of 1.56 (95% CI: 1.32-1.85). The applicability of HRV measurement in preventive settings is discussed.

Childhood adversity and vagal regulation: A systematic review and meta-analysis.

Childhood adversity (CA) is associated with increased risk for physical and mental health problems, with alterations in vagal regulation (an aspect of autonomic functioning indexed by vagally-mediated heart rate variability [vmHRV]) implicated as a mechanism. Three-level meta-analyses were conducted to synthesize research on the relationship between CA and 1) baseline vagal activity, and 2) vagal reactivity to challenges including stress tests, emotion-eliciting tasks and cognitive tasks. No significant overall association was found between CA and vagal activity (r = -.015; p = .11) or vagal reactivity (r = -.017; p = .13). However, analyses controlling for moderator interrelatedness revealed an association between CA and lower baseline vagal activity in samples including participants diagnosed with a psychiatric disorder, and for direct adversities such as maltreatment. For vagal reactivity, CA was associated with lower reactivity if the adversity was experienced less recently, and for studies operationalizing reactivity using task mean levels of vmHRV. These findings indicate that small alterations in vagal functioning occur for specific CA subtypes and subgroups of individuals.

Resting Heart Rate Variability, Perceived Emotion Regulation, and Low-Risk Drug Use in College-Aged Adults: Gender as a Moderator.

Identification of individual differences in drug use is warranted, as a history of use is associated with future drug problems. Such drug use is thought to disrupt inhibitory and motivation networks involved in emotion regulation (ER). Higher resting heart rate variability (HRV), a biomarker of effective inhibitory abilities, is associated with less substance (e.g., alcohol, opioid) use. Higher HRV is associated with lower perceived ER difficulties, and this link is stronger in women relative to men. Evidence suggests women might engage in drug use primarily to reduce stress, and men primarily to induce feelings of elation. Research has yet to examine associations among individuals' difficulties in ER, resting HRV, and a recent history of drug use; the current study explored this, in addition to how these associations might differ as a function of gender. Young and healthy college students (N = 190; 88 women) completed a 5-min baseline to assess resting HRV, followed by the 36-item difficulties in ER Scale and 10-item Drug Abuse Screening Test. Higher difficulties in ER, but not resting HRV, were associated with a greater history of "low-risk" drug use in the full sample and moderation tests confirm this link was stronger in women. Moderated-mediation results confirmed an indirect association between resting HRV and drug use, mediated by self-reported difficulties among women only. A significant association between resting HRV and Difficulties in Emotion Regulation Scale (DERS) emerged only among women without a history of drug use. These results indicate that difficulties in ER are both associated with a low-risk history of drug use and underlie an indirect link between resting HRV and drug use history in women only. Among these women with a history of drug use relative to women without, there was no link between resting HRV and self-reported difficulties in ER, suggesting a disrupted inhibitory-motivational pathway. Additional work is needed to understand the psychophysiological correlates of a history of low-risk drug use in young men. These data are in line with research suggesting gender differences in the motivation to engage in recreational drug use and ER interventions might be important in women who engage in low-risk recreational drug use.

Racial and ethnic differences in perseverative cognition at the onset of the COVID-19 pandemic.

RATIONALE: Coronavirus (COVID-19) disproportionately affects people of color (e.g., Black and Latinx individuals) in the U.S., increasing their morbidity and mortality relative to White people. Despite this greater threat to their well-being, the mental health impact of COVID-19 on people of color remains poorly understood. Perseverative cognition (PC; i.e., excessive worry and/or rumination), is a common psychological response to such threats that independently associates with poor mental and physical health. OBJECTIVE: To examine patterns of PC across race/ethnicity when the COVID-19 pandemic began. METHODS: This study surveyed 6,514 respondents from the NORC AmeriSpeak panel, a probability-based representative national sample of U.S. adults between 3/18/20-4/18/20. We employed traditional statistical analyses and natural language processing of open-ended data to examine pandemic-related worries. RESULTS: Weighted regression analyses with relevant covariates revealed group differences across specific domains of COVID-related worry. Relative to White respondents, Hispanic/Latino respondents reported more worries about social disarray, meeting basic needs, experiencing economic impacts, obtaining healthcare, and contracting COVID-19. Black respondents reported more worry about economic impacts relative to Whites. Additional group differences in worry emerged in open-ended data: Black respondents perseverated about death from COVID-19, whereas Hispanic/Latino respondents reported concerns about COVID-19 spread, and people refusing to uphold mitigation mandates. In contrast, White respondents expressed worry over compromised immune systems and economic collapse. CONCLUSIONS: Results identify significant group differences in COVID-19 related PC, suggesting that people of color faced greater threat to mental well-being at the onset of the pandemic, and may be at greater risk for downstream PC-related physical health consequences.

Heart's eyes to see color: Cardiac vagal tone modulates the impact of ethnicity on selected attention under high load.

The present study tested whether cardiac vagal activity-which is known to play a vital role in social cognition and engagement-predicted the impact of faces of other ethnicity on selective attention under load. Based on the neurovisceral integration theory, we hypothesized that participants with higher resting heart rate variability (HRV) would exhibit better task performance of a target detection task in trials with face distractors of other ethnicity than participants with lower resting HRV, when cognitive resources were scarce under high load. Caucasian participants were instructed to detect a target letter among letter strings superimposed on Black or White male distractor faces under high and low perceptual load. Consistent with the prediction, under high load, HRV was positively correlated with accuracy in trials with Black distractor faces, but not in trials with White distractor faces. The current research demonstrated that individual differences in cardiac vagal tone predicted successful inhibition of an ethnicity-related distractor with limited cognitive resources, which allowed for completing goal-directed behavior more successfully.

Vagally mediated heart rate variability, stress, and perceived social support: a focus on sex differences.

Higher vagally mediated heart rate variability (vmHRV), reflecting vagal activity as indexed by heart function and lower stress vulnerability, is associated with higher perceived social support. Seeking social support is an adaptive stress response, and evolutionary theories suggest that females use this strategy more than males. The current study investigated the hypothesis that higher vmHRV is related to higher perceived social support under conditions of higher, relative to lower, stress, and that this association is most prominent in females. A healthy student sample (n = 143; 82 males, 61 females; mean age 19.9) completed the short version of the Medical outcomes study social support survey (MOS) and the Perceived stress scale (PSS). Activity in the high frequency band of heart rate variability (HF-HRV), deducted from five-minute resting electrocardiogram (ECG) recordings, indexed vmHRV. A moderation analysis was conducted, with PSS and sex as moderators of the association between vmHRV and MOS. Statistical effects were adjusted for age, education, physical activity, body mass index (BMI), alcohol and drug use, ECG-derived respiration (EDR), and mean heart rate. Higher PSS scores moderated the association between vmHRV and MOS in females but not males. Lower PSS scores did not moderate the relation between vmHRV and MOS. This suggests that higher vmHRV is associated with higher perceived social support under conditions of higher stress in females but not males, consistent with evolution of different stress management strategies in the sexes. The results may have implications for individualized intervention strategies for increasing vmHRV and perceived social support.

Gender Differences in Cardiac Chronotropic Control: Implications for Heart Rate Variability Research.

There is a continuing debate concerning "adjustments" to heart period variability [i.e., heart rate variability (HRV)] for the heart period [i.e., increases inter-beat-intervals (IBI)]. To date, such arguments have not seriously considered the impact a demographic variable, such as gender, can have on the association between HRV and the heart period. A prior meta-analysis showed women to have greater HRV compared to men despite having shorter IBI and higher heart rate (HR). Thus, it is plausible that men and women differ in the association between HRV and HR/IBI. Thus, the present study investigates the potential moderating effect of gender on the association between HRV and indices of cardiac chronotropy, including both HR and IBI. Data from 633 participants (339 women) were available for analysis. Cardiac measures were assessed during a 5-min baseline-resting period. HRV measures included the standard deviation of inter-beat-intervals, root mean square of successive differences, and autoregressive high frequency power. Moderation analyses showed gender significantly moderated the association between all HRV variables and both HR and IBI (each p < 0.05). However, results were not consistent when using recently recommended HRV variables "adjusted" for IBI. Overall, the current investigation provides data illustrating a differential association between HRV and the heart period based on gender. Substantial neurophysiological evidence support the current findings; women show greater sensitivity to acetylcholine compared to men. If women show greater sensitivity to acetylcholine, and acetylcholine increases HRV and the heart period, then the association between HRV and the heart period indeed should be stronger in women compared to men. Taken together, these data suggest that routine "adjustments" to HRV for the heart period are unjustified and problematic at best. As it relates to the application of future HRV research, it is imperative that researchers continue to consider the potential impact of gender.

Heart-wired to be cold? Exploring cardiac markers of callous-unemotional traits in incarcerated offenders.

Elevated callous-unemotional (CU) traits have been repeatedly identified in a subgroup of offenders that displays severe antisocial behavior; establishing physiological markers may help improve early identification and treatment efforts. This study examines to what extent baseline-resting heart rate (HR) and heart rate variability (HRV) can be used as markers of CU in incarcerated juvenile and adult offenders. CU traits were assessed using the Inventory of Callous-Unemotional traits. Results of the multiple hierarchical regression tests indicated that there was a small yet significant positive association between baseline HR and CU and negative association between HRV and CU in juvenile offenders with medium model effect sizes (R2 = 0.115 for HR-CU; R2 = 0.126 for HRV-CU). The cardiac markers were unrelated to CU in adult offenders. These findings are important because they demonstrate that impaired cardiac autonomic activity is related to CU traits in juveniles, suggesting that socioemotional processing difficulties should be considered in understanding these deficits. Future research should be conducted in large samples, under reactive and static conditions, while including cardiac covariates, to get more clarity on the interplay between biological systems and behavioral expression.

Smartphone based music intervention in the treatment of episodic migraine headaches - A pilot trial.

OBJECTIVES: Migraine headaches are a prevalent and burdening disorder for the public worldwide. Both traditional preventive drugs and behavioral-based interventions have been used as treatment in the prevention of migraine attacks. However, benefits of alternative interventions in patients with primary headache disorders have not yet been fully explored. The present investigation sought to examine the impact of a patient controlled music intervention (MUSIC CARE) on episodic migraine headache. DESIGN: A sample of 20 episodic migraine patients (17 females, mean age of 42 years) was included in the pilot trial. Patients completed a pre-treatment assessment on headache severity, associated psychopathological distress (anxiety and depression) and functional impairment, and provided reports on their medication intake. During the 3-months intervention period, patients required 1-2 music sessions (based on the "U" sequence) per day with a minimum of 15 per month. RESULTS: Following the intervention, patients reported a significant reduction in the frequency of migraine attacks (MDiff = -2.8, p = .01). Ten patients reported a 50% reduction in the frequency of migraine attacks. Additionally, there was a significant reduction in medication intake (MDiff = -2.85, p = .02), the duration of migraine attacks (MDiff = -5.45, p = .002), anxiety (MDiff = -1.65 (2.88), p = .02) and depression (MDiff = -2.45 (3.5), p = .002). CONCLUSION: These data provide evidence that music intervention may significantly prevent migraine attacks. Moreover, this method is easily accessible and administered. Future well-controlled clinical trials are necessary to further explore the efficiency of the intervention.

The Cardiovascular Conundrum in Ethnic and Sexual Minorities: A Potential Biomarker of Constant Coping With Discrimination.

Background: A paradoxical profile of greater elevated sympathetic vasoconstriction (increased total peripheral resistance, TPR) and increased vagally-mediated heart rate variability (HRV) -the so-called Cardiovascular Conundrum- has been reported in African Americans (AAs) both at rest and in response to orthostasis. Whereas some authors have attributed this pattern to genetic factors, others have pointed to the potential role of coping with repeated racial discrimination. Objective: To disentangle between these alternative explanations, we have examined the hemodynamic profile of another population that is likely to be exposed to episodes of discrimination, i.e., sexual minorities. Methods: The first study was conducted on a sample of AAs and European Americans (EAs) with the aim of replicating previous results on the Cardiovascular Conundrum. In the second study, lesbian, gay, and bisexual (LGB) people, matched by age and sex with heterosexual participants, underwent a hemodynamic and autonomic assessment at rest and during an emotional (in the experimental group, both LGB-related and non LGB related), and a cognitive stressor. Results: The first study confirmed a pattern of higher resting HRV, paired with higher TPR, in AAs compared to EAs. In the second study, compared to heterosexuals, the LGB group showed the Cardiovascular Conundrum pattern, characterized by greater HRV and higher TPR at baseline and a more vascular hemodynamic profile and prominent compensation deficit in response to both tasks, and particularly during the LGB-related emotional task. However, in LGB only, the vascular response was negatively correlated with perceived discrimination. Conclusion: Present preliminary results are discussed in terms of maladaptive physiological consequences of exposure to chronic stress and the chronic use of dysfunctional emotion regulation strategies such as suppression.

A Close Examination of the Use of Systolic Time Intervals in the Calculation of Impedance Derived Cardiac Autonomic Balance and Regulation.

Traditionally, impedance derived measures of cardiac autonomic balance (CAB) and regulation (CAR) are calculated using indices of heart rate variability (HRV) that primarily reflect parasympathetic nervous system activity (e.g., high-frequency HRV | HF-HRV) and pre-ejection period (PEP; a systolic time interval and measure of sympathetic activity). However, HF-HRV and PEP are considered measures of chronotropic and inotropic cardiac influence, respectively. Left ventricular ejection time (LVET) is a systolic time interval that reflects sympathetic chronotropic influence, and therefore may be a more appropriate measure for calculating CAB and CAR compared to PEP. Thus, the current study evaluates both PEP and LVET in the calculation of CAB and CAR. Data from 158 healthy participants (mean age = 19.09 years old, SD = 1.84 years) were available for analyses. CAB and CAR values were calculated using both HF-HRV and the root mean square of successive differences, in addition to both PEP and LVET, in accordance with previously established guidelines. Analyses showed that correlations were significantly weaker between CAB and CAR calculated using LVET for both HF (z = 5.12, p < 0.001) and RMSSD (z = 5.26, p < 0.001) than with PEP. These data suggest that LVET, compared to PEP, provides better "autonomic space" as evidenced by a lack of correlation between CAB and CAR computed using LVET. We stress that future research consider calculating CAB and CAR using chronotropic measures for both parasympathetic and sympathetic activity, as doing so may yield more accurate and independent measures of cardiac autonomic activity compared to a mixture of inotropic (i.e., PEP) and chronotropic (i.e., HF-HRV) measures.

Gender Matters: Nonlinear Relationships Between Heart Rate Variability and Depression and Positive Affect.

Vagally mediated heart rate variability (vmHRV), a measure of the parasympathetic nervous system's control over the heart, is often negatively related to maladaptive emotional outcomes. Recent work suggests that quadratic relationships involving these factors may be present; however, research has not investigated gender differences in these nonlinear functions. To address this gap, the current study tested for quadratic relationships between resting vmHRV and depression and positive affect while investigating gender differences in these relationships. Significant quadratic effects were found between resting vmHRV and reports of both depression symptoms and positive affect in women but not men. Specifically, the lowest levels of depression and the highest levels of positive affect were found at moderate vmHRV in women. These results suggest that examinations of vmHRV's nonlinear associations require the consideration of gender. Our findings are interpreted based on proposed differential neuropsychological mechanisms of vmHRV in men versus women.

Higher cardiac vagal activity predicts lower peripheral resistance 6 years later in European but not African Americans.

African American (AA) individuals are at a greater risk for the development of cardiovascular complications, such as hypertension, compared with European Americans (EAs). Higher vagally mediated heart rate variability (HRV) is typically associated with lower blood pressure (BP) and total peripheral resistance (TPR). However, research has yet to examine the differential impact of HRV on longitudinal hemodynamic activity between AAs and EAs. We sought to rectify this in a sample of 385 normotensive youths (207 AAs, 178 EAs; mean age 23.16 ± 2.9 yr). Individuals participated in two laboratory evaluations spanning approximately 6 yr. Bioimpedance was used to assess HRV at time 1 and cardiac output at both time 1 and time 2. Mean arterial pressure (MAP) was measured at both time points via an automated BP machine. TPR was calculated as MAP divided by cardiac output. Results showed AAs to have higher BP and higher TPR at time 2 compared with EAs, independent of several important covariates. Also, higher HRV at time 1 significantly predicted both lower TPR and BP at time 2 among EAs only; these associations were attenuated and not significant in AAs. HRV did not significantly predict cardiac output at time 2 in the full sample or split by ethnicity. Our findings highlight that AAs show TPR mediated long-term increases in BP irrespective of resting HRV, providing a physiological pathway linking AAs with a greater risk for mortality and morbidity from hypertension and potentially other cardiovascular disease.NEW & NEWSWORTHY African Americans and European Americans differ in hemodynamics underlying long-term blood pressure regulation. Over 6 yr, African Americans show total peripheral resistance-mediated increases in blood pressure compared with European Americans. Higher heart rate variability predicts lower blood pressure and total peripheral resistance 6 yr later in European Americans but not African Americans.