Cardiac vagal control in depression: a critical analysis

Nocturnal heart rate variability moderates the association between sleep-wake regularity and mood in young adults

STUDY OBJECTIVES

Sleep-wake regularity (SWR) is often disrupted in college students and mood disorders are rife at this age. Disrupted SWR can cause repetitive and long-term misalignment between environmental and behavioral cycles and the circadian system which may then have psychological and physical health consequences. We tested whether SWR was independently associated with mood and autonomic function in a healthy adult cohort.

METHODS

We studied 42 college students over a 3 week period using daily sleep-wake diaries and continuous electrocardiogram recordings. Weekly SWR was quantified by the interdaily stability of sleep-wake times (ISSW) and mood was assessed weekly using the Beck Depression Inventory-II. To assess autonomic function, we quantified the high-frequency (HF) power of heart rate variability (HRV). Linear mixed effects models were used to assess the relationship between repeated weekly measures of mood, SWR, and HF.

RESULTS

Low weekly ISSW predicted subsequent poor mood and worsening mood independently of age, sex, race, sleep duration, and physical activity. Although no association was found between ISSW and HF, the ISSW-mood association was significantly moderated by nocturnal HF, i.e. reported mood was lowest after a week with low ISSW and high HF. Prior week mood scores did not significantly predict the subsequent week's ISSW.

CONCLUSIONS

Irregular sleep-wake timing appears to precede poor mood in young adults. Further work is needed to understand the implications of high nocturnal HRV in those with low mood and irregular sleep-wake cycles.

Internalizing Problems and Attentional Control

Abstract. Individuals with internalizing problems differ in levels of attentional control (AC), and this heterogeneity could be associated with differences in autonomic arousal. The present study investigated whether AC moderated the effect of internalizing problems on self-reported experience and autonomic nervous system (ANS) responses after the induction of negative affect. Children aged 9–13 years were recruited into a patient group (29) and a healthy control group (25). AC was measured by the Early Adolescent Temperament Questionnaire. Heart rate, heart rate variability (HRV) and pre-ejection period (PEP) were recorded during baseline, a sad film clip and recovery, and analyzed using a marginal linear model. Children reported their experienced emotion, valence, and arousal in response to the film. A significant interaction effect showed increased HRV and longer PEP from baseline to recovery for patients with higher AC. Patients with lower AC showed increased HRV followed by a return to baseline values after the film clip and no significant changes in PEP. Healthy controls showed no significant changes in HRV or PEP independent of level of AC. There were no differences between groups in self-reported experience. The results indicate that AC moderated the effect of internalizing problems on ANS regulation. Increased HRV and longer PEP from baseline to recovery were uniquely associated with higher AC and internalizing problems. This physiological response might indicate a cognitive avoidance strategy. AC could be an important factor explaining heterogeneity in ANS activity among individuals with internalizing problems. Clinical implications of the present findings are discussed.

Cardiac vagal control mediates the relation between past depression and blood pressure several years later among young adults

Depression has been associated with high blood pressure (BP). However, the mechanisms of the relation between depression and high BP are unclear. We therefore examined whether impaired cardiac vagal control, indexed as low levels of resting respiratory sinus arrhythmia (RSA), serves as a route from depression to high BP. The sample included 125 subjects with histories of depression (probands), 123 never depressed siblings of probands (high-risk siblings), and 156 controls. Resting RSA was assessed at Time 1 (T1) along with BP when subjects were adolescents (M_age  = 16.3 years); systolic and diastolic BP (SBP and DBP) were measured again at Time 2 (T2) when subjects were young adults (M_age  = 22.3 years). Linear mixed-effects models were used to examine the group differences in resting RSA and T2 BP outcomes and to test for RSA mediation of the relation between depression (history or being at high risk) and BP. Resting RSA was lower among probands than controls but was similar among high-risk siblings and controls, while the subject groups did not differ in T2 SBP or DBP. Controlling for T1 BP, depression history indirectly affected T2 DBP (but not SBP) through resting RSA. The findings suggest that, although the direct detrimental effects of depression on BP are not yet evident in young adulthood, among those with depression histories, impaired cardiac vagal control appears to serve as a mechanism of elevated DBP.

Heart Rate Variability for the Prediction of Treatment Response in Major Depressive Disorder

Major depressive disorder (MDD) is one of the disabling diseases in the world-wide, and known to increase cardiac morbidity and mortality. Therefore, previous studies related heart rate variability (HRV) have been conducted to evaluate and diagnose MDD, and to predict treatment outcomes in patient with MDD. We reviewed extensively on the previous peer-reviewed publications associated with this issue, using Pub-Med. In this review article, we introduce the basic concept of HRV and HRV measures, and present several important findings associated with diagnosis and treatment prediction in MDD with using HRV parameters. Furthermore, we discuss the possible underlying mechanism of this phenomenon, and suggest several considerations for the future research.

Heart and Brain Interaction of Psychiatric Illness: A Review Focused on Heart Rate Variability, Cognitive Function, and Quantitative Electroencephalography

Heart rate variability (HRV) reflects beat-to-beat variability in the heart rate due to the dynamic interplay of the sympathetic and parasympathetic nervous systems. HRV is considered an index of the functional status of the autonomic nervous system. A decrease in HRV is thus observed in individuals with autonomic dysfunction. Abnormal HRV has been reported in a range of mental disorders. In this review, we give an overview of HRV in patients with major depressive disorder (MDD), schizophrenia, and posttraumatic stress disorder (PTSD), one of whose core symptoms is cognitive dysfunction. The association between HRV and cognitive function is highlighted in this review. This review consists of three main sections. In the first section, we examine how HRV in patients with MDD, schizophrenia, and PTSD is characterized, and how it is different when compared to that in healthy controls. In the second section, beyond the heart itself, we discuss the intimate connection between the heart and the brain, focusing on how HRV interacts with quantitative electroencephalography (qEEG) in the context of physiological changes in the sleep cycle. Lastly, we finish the review with the examination of the association between HRV and cognitive function. The overall findings indicate that the reduction in HRV is one of main manifestations in MDD, schizophrenia, and PTSD, and also more generally HRV is closely linked to the change in qEEG and also to individual differences in cognitive performance.

Cardiac Vagal Control, Regulatory Processes and Depressive Symptoms: Re-Investigating the Moderating Role of Sleep Quality

Lower cardiac vagal control (CVC), which is often understood as an indicator for impaired regulatory processes, is assumed to predict the development of depressive symptoms. As this link has not been consistently demonstrated, sleep quality has been proposed as a moderating factor. However, previous studies were limited by non-representative samples, cross-sectional data, and focused on CVC as a physiological indicator for impaired regulatory processes, but neglected corresponding subjective measures. Therefore, we investigated whether sleep quality moderates the effects of CVC (quantified by high-frequency heart rate variability) and self-reported regulatory processes (self- and emotion-regulation) on concurrent depressive symptoms and on depressive symptoms after three months in a representative sample (N = 125). Significant interactions between CVC and sleep quality (in women only), as well as self-/emotion-regulation and sleep quality emerged, whereby higher sleep quality attenuated the relation between all risk factors and current depressive symptoms (cross-sectional data). However, there were no significant interactions between those variables in predicting depressive symptoms three months later (longitudinal data). Our cross-sectional findings extend previous findings on sleep quality as a protective factor against depressive symptoms in the presence of lower CVC and subjective indices of impaired regulatory processes. In contrast, our conflicting longitudinal results stress the need for further investigations.

Anxiety, depressive symptoms, and cardiac autonomic function in perimenopausal and postmenopausal women with hot flashes: a brief report

OBJECTIVE

The aim of the study was to examine whether anxiety and depressive symptoms are associated with an adverse cardiac autonomic profile among midlife women with hot flashes.

METHODS

Anxiety and depressive symptoms were evaluated by validated self-administered questionnaires among peri- and postmenopausal women in a randomized trial of slow-paced respiration for hot flashes. Pre-ejection period (PEP), a marker of sympathetic activation, and respiratory sinus arrhythmia (RSA), a marker of parasympathetic activation, were measured at baseline and 12 weeks using impedance cardiography and electocardiography. Multivariable repeated measures linear regression models examined associations between anxiety and depression symptoms and autonomic markers, corrected for multiple comparisons with Benjamini-Hochberg procedure, and adjusted for age and body mass index.

RESULTS

Among the 121 participants, greater state anxiety was associated with shorter PEP, reflecting higher sympathetic activity (β = -0.24, P = 0.02). Greater trait anxiety and cognitive anxiety were associated with lower RSA, reflecting decreased parasympathetic activity (β = -0.03, P < 0.01 for Spielberger Trait Anxiety; β = -0.06, P = 0.02 for Hospital Anxiety and Depression Scale [HADS] Anxiety Subscale). Greater depressive symptoms were associated with lower RSA (β = -0.06, P = 0.03 for HADS Depression Subscale; β = -0.03, P = 0.04 for Beck Depression Inventory).

CONCLUSIONS

Among peri- and postmenopausal women with hot flashes, greater self-reported anxiety and depressive symptoms were associated with lower levels of resting cardiac parasympathetic activity, and greater state anxiety was associated with higher levels of cardiac sympathetic activity. Findings suggest that midlife women with increased anxiety and depressive symptoms may have an unfavorable cardiac autonomic profile with potential implications for their overall cardiovascular risk.

Impact of Mood on Endothelial Function and Arterial Stiffness in Bipolar Disorder

Background

Previous research in bipolar disorder demonstrates greater than expected vascular dysfunction later in the course of illness, proportionate to the cumulative burden of mood symptoms. However, little is known about the effect of acute mood states on vascular function. Here we examine the relation between vascular function and mood state in individuals with bipolar disorder.

Method

This prospective study followed 40 individuals with bipolar disorder for up to 6 months. Participants were assessed for mood state and vascular function at baseline, 2 weeks, and 6 months. Mood state was determined using clinician-administered Montgomery-Åsberg Depression Rating Scale and Young Mania Rating Scale. Vascular function was assessed by flow-mediated dilation (FMD) of the brachial artery, forearm vascular resistance (FVR), and arterial stiffness.

Results

Participants had a mean age of 30.1 years and 75% were male. Primary outcome measures FMD and nitroglycerine-mediated dilation were not found to have statistically significant associations with depressive or manic symptoms. In unadjusted models, higher manic symptoms were significantly associated with increased FVR nitroprusside-mediated dilation and diastolic blood pressure. In adjusted models, higher depressive symptoms were significantly associated with increases in augmentation index adjusted for heart rate of 75 bpm, and higher manic symptoms remained associated with increases in diastolic blood pressure.

Conclusion

FMD may have limited sensitivity as a biomarker for measuring short-term effects of mood state. Longer-term prospective studies are needed to clarify the temporal relation between chronic mood symptoms and vascular function in bipolar disorder.

The persistence of hedonically-based mood repair among young offspring at high- and low-risk for depression

The aim of the present study was to examine whether offspring at high and low familial risk for depression differ in the immediate and more lasting behavioural and physiological effects of hedonically-based mood repair. Participants (9- to 22-year olds) included never-depressed offspring at high familial depression risk (high-risk, n = 64), offspring with similar familial background and personal depression histories (high-risk/DEP, n = 25), and never-depressed offspring at low familial risk (controls, n = 62). Offspring provided affect ratings at baseline, after sad mood induction, immediately following hedonically-based mood repair, and at subsequent, post-repair epochs. Physiological reactivity, indexed via respiratory sinus arrhythmia (RSA), was assessed during the protocol. Following mood induction and mood repair, high- and low-risk (control) offspring reported comparable changes in levels of sadness and RSA. However, sadness increased among high-risk offspring following the post-repair epoch, whereas low-risk offspring maintained mood repair benefits. High-risk/DEP offspring also reported higher levels of sadness following the post-repair epoch than did low-risk offspring. Change in RSA did not differ across the three offspring groups. Self-ratings confirm that one source of difficulty associated with depression risk is diminished ability to maintain hedonically-based mood repair gains, which were not apparent at the physiological level.

A meta-analysis of heart rate variability in major depression

BACKGROUND

Major depression (MD) is a risk factor for cardiovascular disease. Reduced heart rate variability (HRV) has been observed in MD. Given the predictive value of HRV for cardiovascular health, reduced HRV might be one physiological factor that mediates this association.

METHODS

The purpose of this study was to provide up-to-date random-effects meta-analyses of studies which compare resting-state measures of HRV between unmedicated adults with MD and controls. Database search considered English and German literature to July 2018.

RESULTS

A total of 21 studies including 2250 patients and 1982 controls were extracted. Significant differences between patients and controls were found for (i) frequency domains such as HF-HRV [Hedges' g = -0.318; 95% CI (-0.388 to -0.247)], LF-HRV (Hedges' g = -0.195; 95% CI (-0.332 to -0.059)], LF/HF-HRV (Hedges' g = 0.195; 95% CI (0.086-0.303)] and VLF-HRV (Hedges' g = -0.096; 95% CI (-0.179 to -0.013)), and for (ii) time-domains such as IBI (Hedges' g = -0.163; 95% CI (-0.304 to -0.022)], RMSSD (Hedges' g = -0.462; 95% CI (-0.612 to -0.312)] and SDNN (Hedges' g = -0.266; 95% CI (-0.431 to -0.100)].

CONCLUSIONS

Our findings demonstrate that all HRV-measures were lower in MD than in healthy controls and thus strengthens evidence for lower HRV as a potential cardiovascular risk factor in these patients.

Tuning of brain-autonomic coupling by prior threat exposure: Implications for internalizing problems in Mexican-origin adolescents

Exposure to threat increases the risk for internalizing problems in adolescence. Deficits in integrating bodily cues into representations of emotion are thought to contribute to internalizing problems. Given the role of the medial prefrontal cortex in regulating bodily responses and integrating them into representations of emotional states, coordination between activity in the medial prefrontal cortex and autonomic nervous system responses may be influenced by past threat exposure with consequences for the emergence of internalizing problems. A sample of 179 Mexican-origin adolescents (88 female) reported on neighborhood and school crime, peer victimization, and discrimination when they were 10-16 years old. At age 17, participants underwent a functional neuroimaging scan during which they viewed pictures of emotional faces while respiratory sinus arrhythmia (RSA) and skin conductance responses were measured. Adolescents also reported symptoms of internalizing problems. Greater exposure to threats across adolescence was associated with more internalizing problems. Threat exposure was also associated with stronger negative coupling between the ventromedial prefrontal cortex and RSA. Stronger negative ventromedial prefrontal cortex-RSA coupling was associated with fewer internalizing problems. These results suggest the degree of coordinated activity between the brain and parasympathetic nervous system is both enhanced by threat experiences and decreased in adolescents with more internalizing problems.

Sleep disturbance and physiological regulation among young adults with prior depression

Sleep disturbance and respiratory sinus arrhythmia (RSA) are well-known to be independently associated with depression. Yet, it remains unclear how sleep disturbance and impaired physiological regulation (indexed by RSA) may synergistically contribute to depression risk. The current study examined the relationship between sleep disturbance (duration, insomnia) on daily depressive symptoms, and whether RSA moderated this relationship in a sample of young adults with a history of depression. To examine hypotheses, participants (N = 102, ages 18-22) completed a laboratory socio-evaluative stressor task to assess RSA at rest and reactivity. Participants then completed daily measures of sleep duration, insomnia symptoms, and depressive symptoms for two weeks. For main effects, multilevel modeling indicated that shorter overall sleep duration (but not insomnia) predicted higher depressive symptoms, and individual fluctuations in insomnia symptoms (but not sleep duration) predicted higher levels of next-day depressive symptoms. Lower resting RSA, but not reactivity, potentiated these relationships. Individual differences in sleep disturbance (duration and insomnia) predicted prospective levels of depressive symptoms among individuals with lower physiological regulation (indexed by lower RSA), who were particularly vulnerable to the daily effects of sleep disturbance on depressed mood. These results suggest the need to examine both daily sleep disturbance and physiological regulation to understand who may be at greatest risk for depression.

Associations of depression severity with heart rate and heart rate variability in young adults across normative and clinical populations

Limitations of current depression treatments may arise from a lack of knowledge about unique psychophysiological processes that contribute to depression across the full range of presentations. This study examined how individual variations in heart rate (HR) and heart rate variability (HRV) are related to depressive symptoms across normative and clinical populations in 152 young adults (aged 18-35 years). Moderating effects of sex and antidepressant medication status were considered. Electrocardiogram data were collected during "vanilla" baseline and in response to positive and negative emotional cues. Linear regressions and repeated-measures mixed models were used to assess the relationships between Beck Depression Inventory-II (BDI-II) scores, sex, antidepressant use, and cardiovascular outcomes. Baseline models yielded significant main effects of BDI-II and sex on HR and significant interactions between antidepressant medication status and BDI-II on HRV outcomes. The main effects of BDI-II and sex on HR were no longer significant after controlling for cardiorespiratory fitness. Participants who denied current antidepressant use (n = 137) exhibited a negative association and participants who endorsed current antidepressant (n = 15) use exhibited a positive association between BDI-II scores and HRV. Emotional reactivity models were largely non-significant with the exception of a significant main effect of antidepressant medication status on high-frequency HRV reactivity. Results indicated antidepressant medication use may moderate the relationship between depression severity and cardiovascular functioning, but this requires replication given the modest proportion of medicated individuals in this study. Overall, findings suggest cardiovascular processes and cardiorespiratory fitness are linked to depression symptomatology and may be important to consider in depression treatment.

The association between perseverative cognition and resting heart rate variability: A focus on state ruminative thoughts

OBJECTIVE

Two studies were conducted to shed light on the associations between trait and state rumination and worry and a time-domain metric of heart rate variability, the root mean square of successive differences (RMSSD) of cardiac interbeat-interval (IBI).

METHOD

Study 1 involved 130 healthy adults (118 females; mean age = 23.4 ± 3.59 years), while 72 healthy participants (58 females; mean age = 22.2 ± 1.79 years) were involved in Study 2. RMSSD was calculated from a 5-min baseline recording and state ruminative thoughts were assessed during measurement. Trait perseverative cognitions were measured using self-reported questionnaires.

RESULTS

In Study 1, we found that a higher level of state but not trait ruminative thoughts showed weak negative association with lnRMSSD. In Study 2, we replicated the results of Study 1 and we found that trait reflection moderated the relationship between state rumination and lnRMSSD.

CONCLUSION

State rumination may reflect actual cardiovascular activity better than trait preservative cognitions, although trait reflection could be a protective factor.

Lower resting cardiac autonomic balance in young adults with current major depression

Research on cardiac autonomic function in major depressive disorder (MDD) has predominantly examined cardiac vagal control and adopted a model of reciprocal autonomic balance. A proposed bivariate autonomic continuum uses cardiac autonomic balance (CAB) and cardiac autonomic regulation (CAR) models, derived from normalized values of respiratory sinus arrhythmia and pre-ejection period, to more adequately index patterns of autonomic control. The purpose of this study was to assess resting levels of CAB and CAR among young adults with and without a current diagnosis of major depression. One hundred forty-two young adults (n = 65 MDD, n = 77 healthy controls; 20.8 ± 2.6 years) completed a structured diagnostic interview, cardiovascular assessment, and a maximal aerobic fitness test. The findings revealed that CAB, but not CAR, significantly predicted current MDD status (OR = 0.70, 95% CI [0.53, 0.93]), an effect that remained after controlling for aerobic fitness and body mass index. Although CAB was found to be a significant predictor of current MDD status among a sample of young adults, there remained substantial variation in autonomic control that was not captured by the traditional model of reciprocal autonomic balance.

Heart rate variability for treatment response between patients with major depressive disorder versus panic disorder: A 12-week follow-up study

BACKGROUND

Heart Rate Variability (HRV) parameters have been used to evaluate the autonomic nervous system. We hypothesized that patients with major depressive disorder (MDD) and panic disorder (PD) showed different HRV profiles compared to healthy controls. We also hypothesized that we could predict the responder groups in the MDD and PD patients, using differences in HRV indices between the stress and rest phases.

METHODS

28 MDD patients and 29 PD patients were followed for 12 weeks, and we also followed 39 healthy control subjects. We measured HRV parameters at the rest, stress, and recovery phases.

RESULTS

Patients with MDD and PD demonstrated lower pNN50 than controls during the stress (F = 7.49, p = 0.001), and recovery phases (F = 9.43, p = 0.0001). Patients with MDD and PD also showed higher LF/HF ratio than controls during the stress phase (F = 6.15, p = 0.002). Responders in the PD group presented a lower level of LF/HF ratio during the stress phase compared to non-responders (F = 10.14, p = 0.002), while responders in the MDD group showed a lower level of heart rate during all three phases, compared to non-responders. Additionally, we could predict treatment response in patients with MDD using ΔLF/HF ratio (OR: 1.33, 95% CI = 1.07-1.65, p = 0.011) and ΔpNN50 (OR: 1.49, 95% CI 1.09-1.77, p = 0.014).

CONCLUSION

The changes of HRV parameters of pNN50 and LF/HF ratio between the stress and recovery phase may be clinical markers of predictors of treatment responsiveness in MDD and PD patients.

Gut permeability and depressive symptom severity in unmedicated adolescents

OBJECTIVE

This study examined gut permeability in unmedicated adolescents with and without major depressive disorder.

METHOD

Medically healthy, non-medicated, 12-17 year-old females in a major depressive episode (MDE) or healthy controls, without any psychiatric condition, were enrolled. They completed the Children's Depression Rating Scale-Revised (CDRS-R) and underwent a clinical interview. Preejection period (PEP) and respiratory sinus arrhythmia (RSA) data were collected to measure autonomic nervous system activity. Following an overnight fast, participants ingested lactulose and mannitol and collected urine for 4 hours while still fasting, to examine gut permeability. Plasma cytokines (interleukin 1β, interleukin 6, and tumor necrosis factor α) were measured. Correlational analyses were used to examine the associations between relevant variables.

RESULTS

41 female participants (age: 14.8 ± 1.6 years, n = 25 with MDE) were enrolled. PEP, but not RSA, was inversely associated with neurovegetative symptom severity on the CDRS-R (r = -0.31, p < 0.06). In the 30 participants with gut permeability data, the lactulose to mannitol ratio (LMR) was significantly positively associated with depression severity, particularly neurovegetative symptom severity (r = 0.37, p < 0.05). Notably, the association between neurovegetative symptom severity and PEP was substantially reduced after adjusting for LMR. Additionally, depression severity was significantly associated with circulating cytokines.

CONCLUSIONS

This is the first study to examine gut permeability in unmedicated adolescents, offering preliminary support for a mechanistic pathway linking sympathetic nervous system activation to increased gut permeability and activation of the innate immune system, likely contributing to the emergence of neurovegetative symptoms of depression.

The Effect of Single-Dose Massage Session on Autonomic Activity, Mood, and Affective Responses in Major Depressive Disorder

Background: Massage therapy (MT) is a holistic procedure that includes hand pressure (HP), therapeutic communication (TC), and attentive care (AC); together, these procedures could decrease symptoms of depression. Purpose: To study the influence of TC and AC during MT. Methods: Within-subject experimental design with counterbalancing order of treatment. Comparison analysis of the effect of a typical Swedish massage session (SM) with a "sham" massage (ShM; without HP) on the heart rate variability (HRV) mood and affective responses of patients with major depressive disorder (N = 11). During the ShM, clay stones were randomly placed on the body, and the patients were informed about the (sham) therapeutic effect of stones. Findings: A main effect of time showed that after intervention, both SM and ShM increased the HRV (high-frequency power; F[1, 10] = 7.58, p = .02) and reduced scores for anxiety (F[1, 10] = 37.57, p < .001), other feelings (F[1, 10] = 22.64, p = .001), and physical sedation (F[1, 10] = 10.72, p = .008). The SM was associated with more positive affective responses than ShM (qualitative analysis). Conclusions: AC and TC included in MT session improved mood and HRV in the absence of HP. Additional effect on affective responses was observed owing to the HP.

Exercise influence on the microbiome-gut-brain axis

The microbiome in the gut is a diverse environment, housing the majority of our bacterial microbes. This microecosystem has a symbiotic relationship with the surrounding multicellular organism, and a balance and diversity of specific phyla of bacteria support general health. When gut bacteria diversity diminishes, there are systemic consequences, such as gastrointestinal and psychological distress. This pathway of communication is known as the microbiome-gut-brain axis. Interventions such as probiotic supplementation that influence microbiome also improve both gut and brain disorders. Recent evidence suggests that aerobic exercise improves the diversity and abundance of genera from the Firmcutes phylum, which may be the link between the positive effects of exercise on the gut and brain. The purpose of this review is to explain the complex communication pathway of the microbiome-gut-brain axis and further examine the role of exercise on influencing this communication highway.

Heart rate variability as a biomarker of anxious depression response to antidepressant medication

BACKGROUND

There is a need to identify biomarkers of treatment outcomes for major depressive disorder (MDD) that can be disseminated. We investigated the predictive utility of pretreatment heart rate variability (HRV) for outcomes of antidepressant medication in MDD, with pretreatment anxious depression as a hypothesized moderator of HRV effects.

METHODS

A large, randomized, multicenter practical trial (International Study to Predict Optimized Treatment in Depression) in patients with current nonpsychotic MDD (N = 1,008; 722 completers) had three arms: escitalopram, sertraline, and venlafaxine-extended release. At pretreatment, patients were defined as having anxious (N = 309) versus nonanxious (N = 413) depression and their resting high-frequency HRV (root mean square of successive differences) was assessed. Patients' usual treating clinicians managed medication. At 8 weeks, primary outcomes were clinician-rated depressive symptom response and remission; secondary outcomes were self-reported response and remission.

RESULTS

Pretreatment HRV predicted antidepressant outcomes as a function of anxious versus nonanxious depression. In anxious depression, patients with higher HRV had better outcomes, whereas patients with lower HRV had poorer outcomes. In nonanxious depression, patients with lower HRV had better outcomes, whereas patients with higher HRV had poorer outcomes. Some simple effects were not significant. Results did not differ by treatment arm and remained significant when controlling for important covariates.

CONCLUSIONS

These findings inform a precision medicine approach in which clinical and biological assessments may be integrated to facilitate treatment outcome prediction. Knowing about HRV may help determine which patients with anxious depression could benefit from antidepressants and which patients may require a different treatment approach.

Respiratory Sinus Arrhythmia During Sleep and Waking

Abstract. Resting respiratory sinus arrhythmia (RSA) is related to individual differences in waking affective style and self-regulation. However, little is known about the stability of RSA between sleep/wake stages or the relations between RSA during sleep and waking affective style. We examined resting RSA in 25 healthy undergraduates during the waking state and one night of sleep. Stability of cardiac variables across sleep/wake states was highly reliable within participants. As predicted, greater approach behavior and lower impulsivity were associated with higher RSA; these relations were evident in early night Non-REM (NREM) sleep, particularly in slow wave sleep (SWS). The current research extends previous findings by establishing stability of RSA within individuals between wake and sleep states, and by identifying SWS as an optimal period of measurement for relations between waking affective style and RSA.

Cardio-Respiratory Fitness and Autonomic Function in Patients with Major Depressive Disorder

Patients with major depressive disorder (MDD) have an augmented risk of cardiovascular morbidity and mortality. Although a link between depression and autonomic dysfunction as well as reduced cardio-respiratory fitness (CRF) is well documented, the underlying cause is a matter of debate. Therefore, we studied the interplay between autonomic function, body composition and severity of the disease to disentangle possible physiological factors influencing the assumed lack of CRF in MDD patients. We investigated seventeen patients suffering from MDD and seventeen control subjects matched with respect to age, sex, body-mass-index, and smoking habits. A resting baseline assessment and a cardiopulmonary exercise test including a prolonged recovery period were performed to study autonomic function (i.e., heart rate responses and heart rate variability) during rest, exercise and recovery as well as CRF. Most investigated autonomic indices were significantly different at rest, during exercise as well as during recovery indicating altered autonomic modulation. Nevertheless, none of our participants was classified as chronotropically incompetent. As expected, a reduced CRF (i.e., peak oxygen uptake and peak power output, p < 0.01) was observed in patients compared to controls. In addition, a correlation of baseline heart rate and of heart rate during recovery with the ventilatory threshold 1 (p < 0.05) was found in patients only, indicating a relation to the lack of CRF. Furthermore, we observed a positive correlation of the severity of the disease with the weekly sitting time (p < 0.01) as well as a negative correlation with the activity time in the intensity domain walking (p < 0.001) and with the total score of the International Physical Activity Questionnaire (p < 0.01) for patients. This study shows that patients with MDD have altered autonomic function not only during resting conditions but also during exercise as well as recovery from exercise. Intervention studies are needed to evaluate how the described autonomic alterations can be influenced by increasing CRF due to appropriate exercise training programs.

The Effects of Tai Chi on Heart Rate Variability in Older Chinese Individuals with Depression

Background Very little research has been done to simultaneously investigate the effects of Tai Chi (TC) on depression and heart rate variability (HRV). This study, therefore, attempted to explore the effects of TC on depression and on HRV parameters. Methods Sixty older individuals with depression score of 10 or above (the Geriatric Depression Scale, GDS) were randomly assigned into two groups: TC (n = 30) and control group (n = 30). Participants in the experimental group participated in a 24-week TC training program (three 60-min sessions per week), whereas individuals in the control group maintained their unaltered lifestyle. Depression and HRV were measured using the GDS and digital electrocardiogram at baseline and after the 24-week intervention. Results The TC had produced significant positive chances in depression and some HRV parameters (mean heart rate, RMSSD, HF, LFnorm, and HFnorm) (p < 0.05), whereas these positive results were not observed in the control group. Conclusions The results of this study indicated that TC may alleviate depression of the elderly through modulating autonomous nervous system or HRV parameters. This study adds to a growing body of research showing that TC may be effective in treating depression of the elderly. Tai Chi as a mild to moderate mind-body exercise is suitable for older individuals who suffer from depression.

History of childhood emotional abuse predicts lower resting-state high-frequency heart rate variability in depressed women

Childhood emotional abuse impairs emotion regulation and increases risk for major depressive disorder in adulthood. Mounting evidence suggests that decreased resting-state high-frequency heart rate variability, an index of parasympathetic function, represents a transdiagnostic biomarker of emotion dysregulation. We propose that adults with histories of major depressive disorder and childhood emotional abuse represent a subpopulation at particularly high risk to exhibit deficits in parasympathetic control. The current report compared resting-state high-frequency heart rate variability across three groups: (1) depressed women who endorsed childhood emotional abuse (N = 11); (2) depressed women without childhood emotional abuse (N = 19), and (3) never-depressed women without childhood emotional abuse (N = 22). Participants completed childhood trauma self-reports and assessment of resting-state high-frequency heart rate variability. ANCOVAs comparing the three groups after controlling for health-related, psychiatric, and respiratory factors were significant. Depressed women with childhood emotional abuse exhibited lower high-frequency heart rate variability than both groups without childhood emotional abuse (d's ranging from 0.81-0.92). Surprisingly, psychiatric factors were non-significant predictors, indicating that childhood emotional abuse may have a unique impact on autonomic functioning. Future research on larger samples is needed to disentangle the relative and synergistic burdens of depression and childhood trauma on physiologic indicators of emotion dysregulation.

Health, pre-disease and critical transition to disease in the psycho-immune-neuroendocrine network: Are there distinct states in the progression from health to major depressive disorder?

The psycho-immune-neuroendocrine (PINE) network is a regulatory network of interrelated physiological pathways that have been implicated in major depressive disorder (MDD). A model of disease progression for MDD is presented where the stable, healthy state of the PINE network (PINE physiome) undergoes progressive pathophysiological changes to an unstable but reversible pre-disease state (PINE pre-diseasome) with chronic stress. The PINE network may then undergo critical transition to a stable, possibly irreversible disease state of MDD (PINE pathome). Critical transition to disease is heralded by early warning signs which are detectible by biomarkers specific to the PINE network and may be used as a screening test for MDD. Critical transition to MDD may be different for each individual, as it is reliant on diathesis, which comprises genetic predisposition, intrauterine and developmental factors. Finally, we propose the PINE pre-disease state may form a "universal pre-disease state" for several non-communicable diseases (NCDs), and critical transition of the PINE network may lead to one of several frequently associated disease states (influenced by diathesis), supporting the existence of a common Chronic Illness Risk Network (CIRN). This may provide insight into both the puzzle of multifinality and the growing clinical challenge of multimorbidity.

High frequency heart rate variability: Evidence for a transdiagnostic association with suicide ideation

Low levels of high frequency heart rate variability (HF-HRV) have been shown to be associated with suicidal ideation and behavior in students and depressed patients. The goal of the present study was to examine associations between suicide ideation and resting HF-HRV as well as HF-HRV reactivity in a diagnostically heterogeneous sample of adult outpatients with or without concurrent suicide ideation. Participants were N = 85 outpatients (67.1% female; age: M = 38.8, SD = 13.72). HF-HRV reactivity was assessed using a sad film induction method. Associations between resting HF-HRV, HF-HRV reactivity and suicide ideation were analyzed using linear regression modeling - controlling for depression, anxiety and stress. HF-HRV reactivity towards the sad film, but not low resting HF-HRV baseline, was predictive of higher scores on suicidal ideation within the whole sample. In women, lower resting as well as perturbed HF-HRV reactivity was associated with higher scores on suicidal ideation. Results suggest that suicide ideators have a reduced capacity to regulate their response to stress.

Heart rate variability alterations in late life depression: A meta-analysis

OBJECTIVE

There is strong evidence for a bi-directional relationship between heart-health and depression in later life, but the physiological mechanisms underlying this relationship remain unclear. Heart rate variability is one promising factor that might help explain this relationship. We present results of a meta-analysis that considers heart rate variability alterations in older adults with depression.

METHODS

Literature search of Embase, PsychInfo and Medline revealed five clinical studies and six observational studies that examined the relationship between heart rate variability and depression in adults with a mean age over 60. These studies were included in this meta-analysis.

RESULTS

Heart rate variability was reduced among older adults with clinical depression (N = 550), relative to healthy controls (Hedges' g = -0.334, 95%CI [-0.579, -0.090], p = .007). When high-frequency and low-frequency heart rate variability were investigated separately, only low-frequency heart rate variability was significantly reduced in depressed patients (Hedges' g = -0.626, 95%CI [-1.083, -0.169], p = .007). A similar but weaker pattern of results was found in the observational studies. Most findings remained significant among unmedicated depressed older adults.

LIMITATIONS

Evidence of effect-size heterogeneity was found in the clinical studies, indicating the need for more well-designed research in the area.

CONCLUSION

Heart rate variability is reduced among older adults with depression, and this effect is not fully attributable to antidepressant medication use. Specifically, low-frequency heart rate variability may be reduced in depressed older adults. Heart rate variability warrants further attention, as it could help inform research into the prevention and treatment of depression in later life.

Association of Depressive Symptoms and Heart Rate Variability in Vietnam War-Era Twins: A Longitudinal Twin Difference Study

IMPORTANCE

Depressive symptoms are associated with lower heart rate variability (HRV), an index of autonomic dysregulation, but the direction of the association remains unclear.

OBJECTIVE

To investigate the temporal association between depression and HRV.

DESIGN, SETTINGS, AND PARTICIPANTS

A longitudinal, cross-lagged twin difference study, with baseline assessments from March 2002 to March 2006 (visit 1) and a 7-year follow-up (visit 2) at an academic research center with participants recruited from a national twin registry. Twins (n = 166) from the Vietnam Era Twin Registry, who served in the US military during the Vietnam War, and were discordant for depression at baseline were recruited.

MAIN OUTCOMES AND MEASURES

At both visits, depressive symptoms were measured using the Beck Depression Inventory-II (BDI-II), and HRV was measured through 24-hour electrocardiogram monitoring. To assess the direction of the association, within-pair differences in multivariable mixed-effects regression models were examined, and standardized β coefficients for both pathways were calculated. The associations were evaluated separately in monozygotic and dizygotic twins.

RESULTS

In the final analytic sample (N = 146), all participants were men, 138 (95%) were white, and the mean (SD) age was 54 (3) years at baseline. Results showed consistent associations between visit 1 HRV and visit 2 BDI score across all HRV domains and models (β coefficients ranging from -0.14 to -0.29), which were not explained by antidepressants or other participant characteristics. The magnitude of the association was similar in the opposite pathway linking visit 1 BDI score to visit 2 HRV, with β coefficients ranging from 0.05 to -0.30, but it was largely explained by antidepressant use. In stratified analysis by zygosity, significant associations were observed in monozygotic and dizygotic twins for the path linking visit 1 HRV to visit 2 BDI score, although the associations were slightly stronger in dizygotic twins.

CONCLUSIONS AND RELEVANCE

The association between depression and autonomic dysregulation, indexed by HRV, is bidirectional, with stronger evidence suggesting that autonomic function affects depression risk rather than vice versa. The opposite causal pathway from depression to lower HRV is mostly driven by antidepressant use. These findings highlight an important role of autonomic nervous system in the risk of depression and contribute new understanding of the mechanisms underlying the comorbidity of depression and cardiovascular disease.

Psychopathology, everyday behaviors, and autonomic activity in daily life: An ambulatory impedance cardiography study of depression, anxiety, and hypomanic traits

Discrepancies regarding the link between autonomic nervous system (ANS) activity and psychopathology may be due in part to inconsistent measurement of non-psychological factors, including eating, drinking, activity, posture, and interacting with others. Rather than sources of noise, behaviors like being active and being with others may be the behavioral pathways that connect psychopathology symptoms to autonomic activity. The present study examined whether behaviors mediate the association of depression, anxiety, and hypomanic traits with ANS by using experience sampling methodology and ambulatory impedance cardiography. Participants (n = 49) completed measures of affect and one day of experience sampling and ambulatory impedance cardiography. The association of hypomanic traits with heart rate variability and heart rate was mediated by physical activity, and social activity mediated the association of depressive symptoms and respiration. These results highlight the importance of considering the pathways between psychopathology and ANS and the mediating role that everyday behaviors play.

Autonomic and Brain Morphological Predictors of Stress Resilience

Stressful life events are an important cause of psychopathology. Humans exposed to aversive or stressful experiences show considerable inter-individual heterogeneity in their responses. However, the majority does not develop stress-related psychiatric disorders. The dynamic processes encompassing positive and functional adaptation in the face of significant adversity have been broadly defined as resilience. Traditionally, the assessment of resilience has been confined to self-report measures, both within the general community and putative high-risk populations. Although this approach has value, it is highly susceptible to subjective bias and may not capture the dynamic nature of resilience, as underlying construct. Recognizing the obvious benefits of more objective measures of resilience, research in the field has just started investigating the predictive value of several potential biological markers. This review provides an overview of theoretical views and empirical evidence suggesting that individual differences in heart rate variability (HRV), a surrogate index of resting cardiac vagal outflow, may underlie different levels of resilience toward the development of stress-related psychiatric disorders. Following this line of thought, recent studies describing associations between regional brain morphometric characteristics and resting state vagally-mediated HRV are summarized. Existing studies suggest that the structural morphology of the anterior cingulated cortex (ACC), particularly its cortical thickness, is implicated in the expression of individual differences in HRV. These findings are discussed in light of emerging structural neuroimaging research, linking morphological characteristics of the ACC to psychological traits ascribed to a high-resilient profile and abnormal structural integrity of the ACC to the psychophysiological expression of stress-related mental health consequences. We conclude that a multidisciplinary approach integrating brain structural imaging with HRV monitoring could offer novel perspectives about brain-body pathways in resilience and adaptation to psychological stress.

The Heart´s rhythm 'n' blues: Sex differences in circadian variation patterns of vagal activity vary by depressive symptoms in predominantly healthy employees

INTRODUCTION

Successful regulation of emotional states is positively associated to mental health, while difficulties in regulating emotions are negatively associated to overall mental health and in particular associated with anxiety or depression symptoms. A key structure associated to socio-emotional regulatory processes is the central autonomic network. Activity in this structure is associated to vagal activity can be indexed noninvasively and simply by measures of peripheral cardiac autonomic modulations such as heart rate variability. Vagal activity exhibits a circadian variation pattern, with a maximum during nighttime. Depression is known to affect chronobiology. Also, depressive symptoms are known to be associated with decreased resting state vagal activity, but studies investigating the association between circadian variation pattern of vagal activity and depressive symptoms are scarce. We aim to examine these patterns in association to symptom severity of depression using chronobiologic methods.

METHODS

Data from the Manheim Industrial Cohort Studies (MICS) were used. A total of 3,030 predominantly healthy working adults underwent, among others, ambulatory 24-h hear rate-recordings, detailed health examination and online questionnaires and were available for this analysis. The root mean sum of successive differences (RMSSD) was used as an indicator of vagally mediated heart rate variability. Three individual-level cosine function parameters (MESOR, amplitude, acrophase) were estimated to quantify circadian variation pattern. Multivariate linear regression models including important covariates such as age, sex, and lifestyle factors as well as an interaction effect of sex with depressive symptoms were used to estimate the association of circadian variation pattern of vagal activity with depressive symptoms simultaneously.

RESULTS

The analysis sample consisted of 20.2% females and an average age 41 with standard deviation of 11 years. Nonparametric bivariate analysis revealed significant MESOR and amplitude differences between the 90^th percentile split, but not on acrophase. Multivariate linear regression models estimated depressive symptoms to be negatively associated with the 24h mean (MESOR) and oscillation amplitude in men but positively associated in women. This pattern of findings indicates a blunted day-night rhythm of vagal activity in men with greater depressive symptoms as well as a moderation effect of sex in the association of CVP and depressive symptoms.

CONCLUSIONS

This is the first study investigating circadian variation pattern by mild depressive symptoms in a large, rather healthy occupational sample. Depressive symptoms were associated with decreased circadian variation pattern of vagal activity in men but with increased circadian variation pattern in women. The possible underlying mechanism(s) are discussed using the neurovisceral integration model. These findings may have implications for the knowledge on etiology, diagnosis, course, and treatment of depressive symptoms and thus may be of significant public health relevance.

Arterial stiffness is associated with depression in middle-aged men - the Maastricht Study

BACKGROUND

Arterial stiffening may underlie the association between depression and cardiovascular disease (CVD), but reported data are inconsistent. We investigated the associations between aortic stiffness and major depressive disorder (MDD) and depressive symptoms, and whether these differed by sex and age.

METHODS

We measured carotid to femoral pulse wave velocity (cfPWV) using applanation tonometry, and we assessed depression using the Mini-International Neuropsychiatric Interview (MINI) and the Patient Health Questionnaire-9 (PHQ-9) in a cohort of participants from The Maastricht Study. Logistic and negative binominal models were adjusted for age, type 2 diabetes mellitus (T2DM), mean arterial pressure (MAP) and CVD risk factors.

RESULTS

We included 2757 participants in our analyses (48.8% men, mean age 59.8 ± 8.1 yr, 27% T2DM). We found that cfPWV was associated with MDD in men (fully adjusted odds ratio [OR] 2.36, 95% confidence interval [CI] 1.45-3.84), but not in women (OR 1.57, 95% CI 0.93-2.66), aged 60 years or younger. The ORs were not significant in individuals older than 60 years (men: OR 1.03, 95% CI 0.63-1.68; women: OR 0.64, 95% CI 0.32-1.31). Similarly, cfPWV was associated with a higher PHQ-9 score in men (rate ratio 1.28, 95% CI 1.09-1.52), but not in women (rate ratio 1.11, 95% CI 0.99-1.23), aged 60 years or younger. Associations were not significant in individuals older than 60 years (men: rate ratio 0.96, 95% CI 0.84-1.08; women: rate ratio 1.00, 95% CI 0.90-1.12).

LIMITATIONS

We cannot rule out reversed causation in this cross-sectional study.

CONCLUSION

Greater aortic stiffness is associated with MDD and depressive symptoms among middle-aged men and to a lesser extent in women, whereas this association was not observed in old age.

Heart Rate Variability Biofeedback Stress Relief Program for Depression

Background: Depressive disorders often have a chronic course and the efficacy of evidence-based treatments may be overestimated.

Objective: To examine the effectiveness of the Heart Rate Variability Stress Reduction Program (SRP) as a supplement to standard treatment in patients with depressive disorders.

Methods: The SRP was individually administered in eight weekly sessions. Seven participants completed the full protocol and were enrolled in a single-subject ABA multiple baseline experimental design. To perform interrupted time-series analyses, daily measures were completed in a diary (depression, resilience, happiness, heart coherence and a personalized outcome measure).

Results: Five out of seven patients improved in depressed mood and/or a personalized outcome measure. The effect of treatment was reversed in four patients during the withdrawal phase. One patient reliably improved on depression, whereas two patients recovered on autonomy and one on social optimism. No consistent relationship was found between the heart rate variability-related level of coherence and self-reported mood levels.

Conclusions: The SRP is beneficial in some domains and for some patients. A prolonged treatment or continued home practice may be required for enduring effects. The intervention had more clinical impact on resilience-related outcome measures than on symptoms. The small sample size does not permit generalization of the results. We recommend future investigation of the underlying mechanisms of the SRP.

The relationships of current suicidal ideation with inflammatory markers and heart rate variability in unmedicated patients with major depressive disorder

Studies investigating inflammatory status and autonomic functioning simultaneously in depressed patients with current suicidal ideation (SI) are lacking. We recruited 58 unmedicated depressed patients with current SI but without lifetime history of suicidal behavior, as well as 61 equally depressed patients without lifetime history of SI or suicidal behavior. We measured serum cortisol, high-sensitivity C-reactive protein (hs-CRP), erythrocyte sedimentation rate (ESR), and autonomic functioning evaluated by frequency-domain measures of heart rate variability (HRV). The intensity of current SI was rated with the Columbia Suicide Severity Rating Scale. Chronic psychological stress was assessed using the Chinese version of the Perceived Stress Scale (PSS). Patients with current SI showed higher hs-CRP and ESR but lower variance (total HRV), low frequency (LF), and high frequency (HF) HRV than those without lifetime history of SI. We found no differences in cortisol levels and PSS scores. The intensity of current SI was negatively correlated with variance, LF, and HF but positively correlated with hs-CRP. Our results help improve the understanding of the relationships among current SI, inflammation, and autonomic functioning in depressed patients. The combined use of inflammatory markers and HRV indices may one day be applied in predicting and monitoring patients' suicide risk.

Heart rate variability mediates the link between rumination and depressive symptoms: A longitudinal study

Ruminative thinking about negative feelings has been prospectively associated with increases in depressive symptoms and heightened risk for new onsets of major depression. One putative pathophysiological mechanism underlying this link might be represented by autonomic nervous system dysfunction. The objective of this longitudinal study was to evaluate the interplay between rumination, autonomic function (as revealed by heart rate variability (HRV) analysis), and depressive symptoms in healthy young subjects, over a three-year period. Rumination and depressive symptoms were evaluated in twenty-two women and twenty men at three assessment points (Time 0, 1 and 2) by the score on the Ruminative Response Scale, and the Center for Epidemiological Studies Depression Scale, respectively. Vagally-mediated HRV was assessed in a laboratory session (Time 0) and in two ambulatory sessions at Time 1 and Time 2 (~13 and 34months after Time 0, respectively). Ruminative thinking was found to be (i) a stable trait characteristic, (ii) more prevalent in women than men, and (iii) positively correlated with depressive symptoms. Moreover, resting HRV was negatively correlated with both rumination and depressive symptoms. Finally, HRV at Time 1 mediated the relationship between rumination at Time 0 and depressive symptoms at Time 2. We conclude that autonomic dysfunction, specifically low vagal tone, may be prospectively implicated in the generation of depressive symptoms in a non-clinical setting.

Cardiac Vagal Control and Depressive Symptoms: The Moderating Role of Sleep Quality

Lower cardiac vagal control (CVC) has been linked to greater depression. However, this link has not been consistently demonstrated, suggesting the presence of key moderators. Sleep plausibly is one such factor. Therefore, we investigated whether sleep quality moderates the link between CVC (quantified by high-frequency heart rate variability, HF-HRV) and depressive symptoms (assessed using established questionnaires) in 29 healthy women. Results revealed a significant interaction between HF-HRV and sleep quality in predicting depressive symptoms: participants with lower HF-HRV reported elevated depressive symptoms only when sleep quality was also low. In contrast, HF-HRV was not associated with depressive symptoms when sleep quality was high, suggesting a protective function of high sleep quality in the context of lower CVC.

Differences of sympathetic and parasympathetic modulation in major depression

Inconsistent results have been reported with respect to cardiac autonomic function in major depression. The aim of our study was to investigate autonomic function in various branches of the autonomic nervous system in order to better understand parasympathetic and sympathetic modulation in the disease. We investigated 29 unmedicated patients suffering from major depression (MD) in comparison to matched control subjects (gender, age, BMI). The autonomic assessment at rest included values of heart rate variability (HRV), blood pressure variability (BPV), baroreflex sensitivity (BRS), respiration, skin conductance (SC) as well as the calculation of pupillary diameter and the unrest index (PUI). Results were compared by means of a multivariate analysis of variance. In a classification analysis, we identified suitable parameters for patient - control separation. Finally, to analyze interrelations of pupillometric parameters and autonomic indices, we estimated Pearson correlation coefficients and fitted a linear regression model. Apart from a significantly increased heart rate (75±12 vs. 65±6min^-1, p<0.001) and decreased BRS (14±13 vs. 20±15ms/mmHg, p<0.05), we observed a lack of significant differences in HRV and BPV analysis between patients and controls. However, pupillary diameter (left: 4.3±0.9 vs. 3.8±0.6, p<0.01; right: 4.3±0.9 vs. 3.7±0.6mm, p<0.01) and PUI (left: 14.8±6.0 vs. 10.7±4.5mm/min, p<0.01; right: 14.1±5.5 vs. 10.7±4.8mm/min, p<0.01), as well as the level (left: 7.3±6.2 vs. 4.3±4.4 μS, p<0.05) and fluctuations of skin conductance (left: 4.2±4.1 vs. 2.5±3.6, p<0.05; right: 4.2±4.4 vs. 2.6±3.2, p<0.05) were significantly different. The classification accuracy was 88.5% with high specificity (e=92.9%) and sensitivity (s=83.3%) including heart rate, PUI and skin conductance. HRV indices correlated to PUI in controls but not in patients. Our data add evidence to the current debate on autonomic function in major depression. We suggest that diverse results are mainly caused by methodological shortcomings, in particular by the application of HRV assessment only, which misses changes of sympathetic modulation. The application of broader analyzing tools will clarify the pattern of autonomic function in depression and ultimately its role in cardiac morbidity and mortality.

Childhood adversity predicts reduced physiological flexibility during the processing of negative affect among adolescents with major depression histories

BACKGROUND

Adversity during early development has been shown to have enduring negative physiological consequences. In turn, atypical physiological functioning has been associated with maladaptive processing of negative affect, including its regulation. The present study therefore explored whether exposure to adverse life events in childhood predicted maladaptive (less flexible) parasympathetic nervous system functioning during the processing of negative affect among adolescents with depression histories.

METHODS

An initially clinic-referred, pediatric sample (N=189) was assessed at two time points. At Time 1, when subjects were 10.17years old (SD=1.42), on average, and were depressed, parents reported on adverse life events the offspring experienced up to that point. At Time 2, when subjects were 17.18years old (SD=1.28), and were remitted from depression, parents again reported on adverse life events in their offspring's lives for the interim period. At time 2, subjects' parasympathetic nervous system functioning (quantified as respiratory sinus arrhythmia) also was assessed at rest, during sad mood induction, and during instructed mood repair.

RESULTS

Extent of adverse life events experienced by T1 (but not events occurring between T1 and T2) predicted less flexible RSA functioning 7years later during the processing of negative affect. Adolescents with more extensive early life adversities exhibited less vagal withdrawal following negative mood induction and tended to show less physiological recovery following mood repair.

CONCLUSIONS

Early adversities appear to be associated with less flexible physiological regulatory control during negative affect experience, when measured later in development. Stress-related autonomic dysfunction in vulnerable youths may contribute to the unfavorable clinical prognosis associated with juvenile-onset depression.

Inflexibility as a Vulnerability to Depression: A Systematic Qualitative Review

The study of vulnerabilities to depression typically identifies factors that are thought to be universally maladaptive or adaptive. In contrast, researchers recently have theorized that the ability to flexibly engage in different thoughts and behaviors that fit situational demands may be most indicative of psychological health. We review empirical evidence from 147 studies reporting associations between five components of flexibility (set-shifting, affective set-shifting, cardiac vagal control, explanatory flexibility, and coping flexibility) and depression and classify studies according to strength of study design. Evidence from correlational and case-controlled studies suggests cross-sectional relationships, but few prospective studies have been conducted. We discuss limitations of existing studies, identify new directions for programmatic research, and discuss implications that flexibility has for the prevention and treatment of depression.

Physiological Markers of Interpersonal Stress Generation in Depression

Abnormalities in parasympathetic nervous system activity have been linked to depression, but less is known about processes underlying this relationship. The present study evaluated resting and stress-reactive respiratory sinus arrhythmia (RSA) to a laboratory stressor as predictors of daily interpersonal stress generation and depressive symptoms, whether stress generation mediated the relationship between RSA and depressive symptoms, and potential sex differences. A sample of formerly depressed 102 emerging adults (18-22 years; 78% female) completed a laboratory stressor and daily assessments of stressors and depressive symptoms over two weeks. Multilevel modeling revealed that: 1) lower resting RSA predicted daily depressive symptoms; 2) less RSA reactivity predicted interpersonal stress generation, 3) interpersonal dependent stressors mediated the relationship between RSA reactivity and daily depressive symptoms, and 4) sex differences occurred in the resting RSA-depression relationship. These findings highlight the importance of resting RSA and RSA reactivity in the examination of depression and interpersonal processes.