Differences of sympathetic and parasympathetic modulation in major depression

Under pressure: A systematic review of the association between blood pressure variability with depression and anxiety

Blood pressure variability (BPV) impacts brain health by influencing brain structure and cerebrovascular pathologies, though the mechanisms are poorly understood. Changes in the cerebrovasculature may lead to late-onset depression, cognitive impairment, and dementia, however the relationship between BPV with depression and anxiety remains unclear, due to methodological differences and inconsistencies in past research. This review aims to clarify the association between BPV with depression and anxiety in adults to inform understandings of the mechanisms implicating BPV in cognitive health. A systematic search from inception through to January 2024 was performed on Embase, PubMed, PsycINFO, and Web of Science. Studies that assessed BPV quantified by beat-to-beat, 24-hour, or visit-to-visit were eligible if the standardised assessment of depression and/or anxiety were reported as a linear association, or mean differences across control and affect groups. A total of 14 articles reporting on 13 samples and N = 5055 persons met the inclusion criteria (median female proportion = 61 %, range 0 % - 76 %). A meta-analysis was not possible due to methodological heterogeneity in BPV measurements and metrics across studies. Mixed results were observed across depression studies with inconsistencies and variation in the direction, strength of association, and BPV metric. There was weak evidence from only three studies to support a linear association between systolic coefficient of variation and anxiety. Collectively, the findings contribute to understanding the association between BPV and brain health, suggesting that any relationship between BPV and brain structures critical for cognitive function are independent of depression and only modestly implicate anxiety.

The impact of attention bias modification training on behavioral and physiological responses

Attention bias modification training aims to alter attentional deployment to symptom-relevant emotionally salient stimuli. Such training has therapeutic applications in the management of disorders including anxiety, depression, addiction and chronic pain. In emotional reactions, attentional biases interact with autonomically-mediated changes in bodily arousal putatively underpinning affective feeling states. Here we examined the impact of attention bias modification training on behavioral and autonomic reactivity. Fifty-eight participants were divided into two groups. A training group (TR) received attention bias modification training to enhance attention to pleasant visual information, while a control group (CT) performed a procedure that did not modify attentional bias. After training, participants performed an evaluation task in which pairs of emotional and neutral images (unpleasant-neutral, pleasant-neutral, neutral-neutral) were presented, while behavioral (eye movements) and autonomic (skin conductance; heart rate) responses were recorded. At the behavioral level, trained participants were faster to orientate attention to pleasant images, and slower to orientate to unpleasant images. At the autonomic level, trained participants showed attenuated skin conductance responses to unpleasant images, while stronger skin conductance responses were generally associated with higher anxiety. These data argue for the use of attentional training to address both the attentional and the physiological sides of emotional responses, appropriate for anxious and depressive symptomatology, characterized by atypical attentional deployment and autonomic reactivity.

Neurobiological Underpinnings of Hyperarousal in Depression: A Comprehensive Review

Patients with major depressive disorder (MDD) exhibit an abnormal physiological arousal pattern known as hyperarousal, which may contribute to their depressive symptoms. However, the neurobiological mechanisms linking this abnormal arousal to depressive symptoms are not yet fully understood. In this review, we summarize the physiological and neural features of arousal, and review the literature indicating abnormal arousal in depressed patients. Evidence suggests that a hyperarousal state in depression is characterized by abnormalities in sleep behavior, physiological (e.g., heart rate, skin conductance, pupil diameter) and electroencephalography (EEG) features, and altered activity in subcortical (e.g., hypothalamus and locus coeruleus) and cortical regions. While recent studies highlight the importance of subcortical-cortical interactions in arousal, few have explored the relationship between subcortical-cortical interactions and hyperarousal in depressed patients. This gap limits our understanding of the neural mechanism through which hyperarousal affects depressive symptoms, which involves various cognitive processes and the cerebral cortex. Based on the current literature, we propose that the hyperconnectivity in the thalamocortical circuit may contribute to both the hyperarousal pattern and depressive symptoms. Future research should investigate the relationship between thalamocortical connections and abnormal arousal in depression, and explore its implications for non-invasive treatments for depression.

Heart rate variability status at rest in adult depressed patients: a systematic review and meta-analysis

Purposes

A meta-analysis was conducted to examine the differences in heart rate variability (HRV) between depressed patients and healthy individuals, with the purpose of providing a theoretical basis for the diagnosis of depression and the prevention of cardiovascular diseases.

Methods

To search China National Knowledge Infrastructure (CNKI), WanFang, VIP, PubMed, Web of Science, Science Direct, and Cochrane Library databases to collect case-control studies on HRV in depressed patients, the retrieval date is from the establishment of the database to December 2022. Effective Public Health Practice Project (EPHPP) scale was used to evaluate literature quality, and Stata14.0 software was used for meta-analysis.

Results

This study comprised of 43 papers, 22 written in Chinese and 21 in English, that included 2,359 subjects in the depression group and 3,547 in the healthy control group. Meta-analysis results showed that compared with the healthy control group, patients with depression had lower SDNN [Hedges' g = -0.87, 95% CI (-1.14, -0.60), Z = -6.254, p < 0.01], RMSSD [Hedges' g = -0.51, 95% CI (-0.69,-0.33), Z = -5.525, p < 0.01], PNN50 [Hedges' g = -0.43, 95% CI (-0.59, -0.27), Z = -5.245, p < 0.01], LF [Hedges' g = -0.34, 95% CI (-0.55, - 0.13), Z = -3.104, p < 0.01], and HF [Hedges' g = -0.51, 95% CI (-0.69, -0.33), Z = -5.669 p < 0.01], and LF/HF [Hedges' g = -0.05, 95% CI (-0.27, 0.18), Z = -0.410, p = 0.682] showed no significant difference.

Conclusion

This research revealed that HRV measures of depressed individuals were lower than those of the healthy population, except for LF/HF, suggesting that people with depression may be more at risk of cardiovascular diseases than the healthy population.

A review of clinical studies of electrodermal activity and transcranial magnetic stimulation

There is a growing body of evidence indicative of changes in autonomic nervous system (ANS) activity in patients with disorders of the central nervous system (CNS). Non-invasive measures of the ANS, including heart rate variability (HRV), electrodermal activity (EDA), and pupillary light reflex (PLR) may have value as markers of symptom severity, subtype, risk profile, and/or treatment response. In this paper we provide an introduction into the anatomy and physiology of EDA and review the literature published after 2007 in which EDA was an outcome measure of cortical stimulation with transcranial magnetic stimulation (TMS). Eleven studies were included and considered regarding the potential of EDA as an outcome measure reflecting ANS activity in TMS research and treatment. These studies are summarized according to study population, experimental methodology, cortical region targeted, and correlation with other measures of ANS activity. Results indicate that EDA changes vary with the frequency and target of TMS. Inhibitory TMS to the dorsolateral prefrontal cortex (dlPFC) was the most common paradigm in these studies, consistently resulting in decreased EDA.

Impact of antidepressant use on the autonomic nervous system: A meta-analysis and systematic review

Changes in cardiac autonomic nervous system (ANS) regulation observed in psychiatric disorders may be mitigated by antidepressants. We meta-analyzed and systematically reviewed studies examining antidepressants' effects on ANS outcomes, including heart rate variability (HRV). We conducted a PRISMA/MOOSE-compliant search of PubMed and Scopus until March 28th, 2022. We included randomized placebo-controlled trials (RCTs) and pre-post studies, regardless of diagnosis. We pooled results in random-effects meta-analyses, pooling homogeneous study designs and outcomes. We conducted sensitivity analyses and assessed quality of included studies. Thirty studies could be meta-analyzed. Selective serotonin reuptake inhibitors (SSRIs) were significantly associated with a reduction in the square root of the mean-squared difference between successive R-R intervals (RMSSD) (SMD= -0.48) and skin conductance response (SMD= -0.55) in RCTs and with a significant increase in RMSSD in pre-post studies (SMD=0.27). In pre-post studies, tricyclic antidepressants (TCAs) were associated with a significant decrease in several HRV outcomes while agomelatine was associated with a significant increase in high frequency power (SMD= 0.14). In conclusion, SSRIs reduce skin conductance response but have no or inconclusive effects on other ANS outcomes, depending on study design. TCAs reduce markers of parasympathetic function while agomelatine might have the opposite effect. Studies are needed to investigate the impact of SSRIs on the recovery of cardiac ANS regulation after acute myocardial infarction, and the effects of newer antidepressants.

Temporal profile of intranasal oxytocin in the human autonomic nervous system at rest: An electrocardiography and pupillometry study

BACKGROUND

Human social behavior is modulated by oxytocin (OT). Intranasal administration of OT (IN-OT) is a noninvasive route shown to elicit changes in the autonomic nervous system (ANS) activity; however, IN-OT's effect on the temporal profile of ANS activity at rest is yet to be described.

AIMS

We aimed to describe the temporal profile of IN-OT at six 10-min time windows from 15- to 100-min post-administration in 20 male participants at rest while continuously recording their pupillary in an eyes-open condition and cardiac activity in eyes-open and eyes-closed conditions.

METHODS

We used a double-blind, placebo-controlled, within-subjects design study where we extracted two proxies of parasympathetic nervous system (PNS) activity: high-frequency heart rate variability (HF-HRV) and pupillary unrest index (PUI); and a proxy of sympathetic nervous system activity: sample entropy of the pupillary unrest.

RESULTS

In the eyes-open condition, we found an effect of IN-OT on the proxies of PNS activity: decreased PUI in the three-time windows post-administration spanning 65-100 min, and as an exploratory finding, an increased HF-HRV in the 80-85 min time window.

CONCLUSIONS

We suggest there is a role of OT in PNS regulation that may be consistent with OT's currently theorized role in the facilitation of alertness and approach behavior.

A comparative evaluation of resting state proxies of sympathetic and parasympathetic nervous system activity in adolescent major depression

Major depressive disorder (MDD) is associated with autonomic nervous system (ANS) dysfunction, characterized by decreased parasympathetic (PNS) and increased sympathetic (SNS) activity. Although findings on reduced PNS activity in adult MDD have been replicated in adolescents, comprehensive studies assessing PNS and SNS proxies in underage patients with MDD are scarce. Proxies of resting PNS (heart rate variability (HRV) and SNS activity (skin conductance response [SCR] and salivary alpha amylase [sAA], as well as mixed activity (heart rate [HR]) were collected in adolescents with MDD (n = 29) and non-depressed controls (n = 29). Primary analyses addressed differences between groups and correlations with depression severity. Patients with MDD showed significantly decreased HRV (g = - 0.87; 95% CI [- 1.39; - 0.35]) and increased HR (g = 0.66; 95% CI [0.14; 1.18]). Proxies of pure SNS activity showed no significant differences between groups. HR (positive) and HRV (negative) were significantly correlated with self- and clinician-rated depression severity. Alterations of ANS activity are evident in adolescent MDD, but characterized by decreased PNS activity only. We found no evidence for altered SNS activity. Findings suggest that ANS dysfunction early in the course of MDD might be predominantly driven by decreased PNS activity.

When Heart Beats Differently in Depression: Review of Nonlinear Heart Rate Variability Measures

BACKGROUND

Disturbed heart dynamics in depression seriously increases mortality risk. Heart rate variability (HRV) is a rich source of information for studying this dynamics. This paper is a meta-analytic review with methodological commentary of the application of nonlinear analysis of HRV and its possibility to address cardiovascular diseases in depression.

OBJECTIVE

This paper aimed to appeal for the introduction of cardiological screening to patients with depression, because it is still far from established practice. The other (main) objective of the paper was to show that nonlinear methods in HRV analysis give better results than standard ones.

METHODS

We systematically searched on the web for papers on nonlinear analyses of HRV in depression, in line with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) 2020 framework recommendations. We scrutinized the chosen publications and performed random-effects meta-analysis, using the esci module in jamovi software where standardized effect sizes (ESs) are corrected to yield the proof of the practical utility of their results.

RESULTS

In all, 26 publications on the connection of nonlinear HRV measures and depression meeting our inclusion criteria were selected, examining a total of 1537 patients diagnosed with depression and 1041 healthy controls (N=2578). The overall ES (unbiased) was 1.03 (95% CI 0.703-1.35; diamond ratio 3.60). We performed 3 more meta-analytic comparisons, demonstrating the overall effectiveness of 3 groups of nonlinear analysis: detrended fluctuation analysis (overall ES 0.364, 95% CI 0.237-0.491), entropy-based measures (overall ES 1.05, 95% CI 0.572-1.52), and all other nonlinear measures (overall ES 0.702, 95% CI 0.422-0.982). The effectiveness of the applied methods of electrocardiogram analysis was compared and discussed in the light of detection and prevention of depression-related cardiovascular risk.

CONCLUSIONS

We compared the ESs of nonlinear and conventional time and spectral methods (found in the literature) and demonstrated that those of the former are larger, which recommends their use for the early screening of cardiovascular abnormalities in patients with depression to prevent possible deleterious events.

Inconclusive evidence that breathing shapes pupil dynamics in humans: a systematic review

More than 50 years ago, it was proposed that breathing shapes pupil dynamics. This widespread idea is also the general understanding currently. However, there has been no attempt at synthesizing the progress on this topic since. We therefore conducted a systematic review of the literature on how breathing affects pupil dynamics in humans. We assessed the effect of breathing phase, depth, rate, and route (nose/mouth). We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, and conducted a systematic search of the scientific literature databases MEDLINE, Web of Science, and PsycInfo in November 2021. Thirty-one studies were included in the final analyses, and their quality was assessed with QualSyst. The study findings were summarized in a descriptive manner, and the strength of the evidence for each parameter was estimated following the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. The effect of breathing phase on pupil dynamics was rated as "low" (6 studies). The effect of breathing depth and breathing rate (6 and 20 studies respectively) were rated as "very low". Breathing route was not investigated by any of the included studies. Overall, we show that there is, at best, inconclusive evidence for an effect of breathing on pupil dynamics in humans. Finally, we suggest some possible confounders to be considered, and outstanding questions that need to be addressed, to answer this fundamental question. Trial registration: This systematic review has been registered in the international prospective register of systematic reviews (PROSPERO) under the registration number: CRD42022285044.

Electrophysiological correlates of mindfulness in patients with major depressive disorder

Objectives

Mindfulness-based interventions (MBI) can reduce both stress and depressive symptoms. However, the impact of mindfulness on stress level in depressed subjects remains unclear. This study aims to assess electrophysiological correlates of mindfulness in patients with major depressive disorder (MDD) at baseline, under stress exposure, and in relaxation following stress exposure.

Methods

Perceived mindfulness was assessed with the Freiburger Mindfulness Inventory (FMI) in 89 inpatients (mean age 51) with MDD [mean Beck Depression Inventory (BDI) 30]. Electrophysiological parameters [resting heart rate (RHR), heart rate variability (HRV), respiration rate, skin conductance, and skin temperature] were recorded at 5-min baseline, 1-min stress exposure, and 5-min self-induced relaxation.

Results

Freiburger Mindfulness Inventory was strongly inversely correlated with symptom severity measured by BDI (r = –0.53, p < 0.001). No correlations between FM score and electrophysiological parameters in any of the three conditions (baseline, stress exposure, relaxed state) could be found. The factor openness was associated with higher VLF (very low frequency of HRV) in the baseline condition. However, this correlation was no more significant after regression analysis when corrected for respiratory rate, age, and sex.

Conclusion

Autonomous nervous reactivity in depression was not associated with perceived mindfulness as measured by FMI score and presented electrophysiological parameters, despite the strong inverse correlation between state mindfulness and symptom severity.

Immune transcriptional profiles in mothers with clinically elevated depression and anxiety symptoms several years post-delivery

BACKGROUND

Most research on maternal mental health focuses on the perinatal period and does not extend beyond 12 months postpartum. However, emerging evidence suggests that for some women (30%-50%), psychological symptoms may persist beyond the first year postpartum or even emerge later increasing the risk of chronic mood and anxiety symptoms. Despite the high prevalence rates and devastating maternal-child consequences, studies examining maternal depression, anxiety, and post-traumatic stress disorder (PTSD) beyond the first year postpartum are rare and our understanding of the underlying biological mechanisms is incomplete. Inflammatory processes are thought to be involved in the pathophysiology of depression, anxiety, & PTSD outside of the postpartum period. Therefore, the purpose of the current investigation was to examine the relationship between depression, anxiety, and PTSD two to three years post-delivery, and transcriptional control pathways relevant to inflammatory and antiviral processes.

METHODS

Women over 18 years of age enrolled in ongoing research studies at Cedars Sinai Medical Center who were 2-3 years postpartum were invited to participate in the current study. Women (N = 33) reported on their levels of depression, anxiety, and PTSD and provided a blood sample approximately 2-3 years post-delivery. Bioinformatic analyses of differential gene expression (DGEs) to infer transcription factor activity were used. Gene expression was assayed by RNA sequencing and TELiS bioinformatics analysis of transcription factor-binding motifs in the promoters of differentially expressed genes.

RESULTS

DGE analyses revealed that women with clinically elevated symptoms of depression, anxiety and PTSD (n = 16) showed upregulation of genes activated by transcription control pathways associated with inflammation (NF-_Κ B, p = 0.004; JUN, p = 0.02), including ꞵ-adrenergic responsive CREB (p = 0.01) and reduced activation of genes associated with the antiviral response (IRFs, p = 0.02) and the glucocorticoid signaling pathway (GR, p = 0.02) compared to women without clinical symptoms (n = 17).

CONCLUSIONS

This is one of the first investigations into the immune signaling pathways involved in depression, anxiety, and PTSD two to three years post-delivery. The results of this study suggest that clinically elevated symptoms of depression, anxiety, and PTSD two to three years post-delivery are associated with a gene expression profile characterized by upregulated expression of pro-inflammatory genes and downregulated expression of antiviral genes. The data also point to two potential stress responsive pathways linking symptoms to increased inflammatory signaling in immune cells: sympathetic nervous system mediated ꞵ-adrenergic signaling and reduced hypothalamic pituitary adrenal axis activity. Together, these findings highlight the need for investigations into maternal mental health beyond the first year postpartum. This article is protected by copyright. All rights reserved.

The Role of Depressive Disorders in Autonomic Cardiovascular Dysregulation in Fibromyalgia

OBJECTIVE

Previous research revealed aberrances in autonomic cardiovascular regulation in fibromyalgia, which may be relevant to symptoms genesis and the increased risk of cardiovascular disorders in individuals with fibromyalgia. This study investigated the role of comorbid depression in autonomic cardiovascular dysregulations in fibromyalgia.

METHODS

Cardiovascular recordings were obtained in 53 participants with fibromyalgia who also had depression ( n = 27), in participants with fibromyalgia without depression ( n = 26), and in 29 healthy controls, at rest and during a cold pressor test and an arithmetic task. Assessed parameters included interbeat interval, blood pressure, heart rate variability, baroreflex sensitivity, stroke volume, preejection period, left ventricular ejection time, Heather index, and total peripheral resistance.

RESULTS

Participants with both fibromyalgia and depression displayed lower tonic interbeat interval, baroreflex sensitivity, and heart rate variability compared with participants with fibromyalgia without depression and controls ( p values < .012, d values = 0.71-1.06). Participants with fibromyalgia but without depression did not differ from controls in these variables. Moreover, participants with fibromyalgia who also had depression, but not those without depression, exhibited lower Heather index, stroke volume, and left ventricular ejection time compared with controls ( p values < .013, d values = 0.62-0.78). No group differences arose for preejection period or total peripheral resistance. Stress reactivity was reduced in participants with fibromyalgia, independently of depression, for diastolic blood pressure, interbeat interval, left ventricular ejection time, and heart rate variability, than in controls.

CONCLUSIONS

The role of depression in the autonomic dysregulation in fibromyalgia involves chronotropic cardiac control rather than adrenergic influences on contractility and vascular tone. Blunted cardiovascular reactivity may be ascribable to pathological factors inherent to fibromyalgia. These results underline the importance of diagnostics and treatment of comorbid depressive disorders in the management of fibromyalgia.

Depressive rumination and heart rate variability: A pilot study on the effect of biofeedback on rumination and its physiological concomitants

Objective

Recent studies suggest that lower resting heart rate variability (HRV) is associated with elevated vulnerability to depressive rumination. In this study, we tested whether increases in HRV after HRV-biofeedback training are accompanied by reductions in rumination levels.

Materials and methods

Sixteen patients suffering from depression completed a 6-week HRV-biofeedback training and fourteen patients completed a control condition in which there was no intervention (waitlist). The training included five sessions per week at home using a smartphone application and an ECG belt. Depressive symptoms and autonomic function at rest and during induced rumination were assessed before and after each of the two conditions. We used a well-established rumination induction task to provoke a state of pervasive rumination while recording various physiological signals simultaneously. Changes in HRV, respiration rate, skin conductance, and pupil diameter were compared between conditions and time points.

Results

A significant correlation was found between resting HRV and rumination levels, both assessed at the first laboratory session (r = -0.43, p < 0.05). Induction of rumination led to an acceleration of heart rate and skin conductance increases. After biofeedback training, resting vagal HRV was increased (p < 0.01) and self-ratings of state anxiety (p < 0.05), rumination (p < 0.05), perceived stress (p < 0.05), and depressive symptoms (QIDS, BDI; both p < 0.05) were decreased. In the control condition, there were no changes in autonomic indices or depressive symptomatology. A significant interaction effect group x time on HRV was observed.

Conclusion

Our results indicate that a smartphone-based HRV-biofeedback intervention can be applied to improve cardiovagal function and to reduce depressive symptoms including self-rated rumination tendencies.

Symptoms of depression are related to sedentary behavior and sleep duration in elderly individuals: A cross-sectional study of 49,317 older Chinese adults

OBJECTIVE

Depression is a common mental disorder in older adults. This study aimed to determine the incidence of depression and the relationship between sedentary behavior and sleep duration in elderly individuals.

METHOD

A total of 49,317 elderly adults from eight health centers in six Chinese provinces completed an online self-reported health questionnaire. Logistic regression was used to explore the association between sedentary behavior, sleep duration, and depression symptoms.

RESULTS

Symptoms of depression were present in 20.1% of older adults. Sedentary behaviors for >6 h/day (OR = 3.16; 95% CI: 2.90-3.44; p < 0.001) were a greater risk factor for depressive symptoms in older adults than sedentary behaviors for less than 3 h/day. Elderly individuals with short sleep durations (<7 h/day) were more likely to experience depression (OR = 2.20; 95% CI: 2.07-2.34; p < 0.001).

CONCLUSION

This study suggested that sedentary behavior and short sleep duration in older Chinese adults are associated with depressive symptoms. In China, further improvement of the mental health and lifestyle of elderly individuals may be warranted.

The indirect impact of heart rate variability on cold pressor pain tolerance and intensity through psychological distress in individuals with chronic pain: the Tromsø Study

Supplemental Digital Content is Available in the Text. The hypoalgesic impact of cardiovascular regulatory systems on evoked pain responsiveness in those with chronic pain is conveyed via the indirect effects of psychological distress.

Introduction:

Chronic pain (CP) patients often display lower heart rate variability (HRV) and baroreceptor sensitivity (BRS), which are associated with increased evoked pain intensity and decreased pain tolerance.

Objective:

The purpose of this study was to test whether the association between low levels of HRV and BRS and increased evoked pain responsiveness in individuals with CP is mediated by psychological distress and whether this mediation is sex dependent.

Methods:

The sample consisted of 877 participants in Wave 6 of the Tromsø population study who reported clinically meaningful CP. Resting HRV and BRS parameters were derived from continuous beat-to-beat blood pressure recordings. Psychological distress was assessed using the Hopkins Symptom Checklist-10. After cardiovascular assessment, participants completed a 106-second cold pressor task (3°C bath), which assessed cold pressor pain intensity (CPI) and cold pressor pain tolerance (CPT).

Results:

In the full CP sample, mediation analyses showed significant indirect effects, without direct effects, of HRV and BRS on both CPT and CPI via psychological distress. When stratified by sex, significant indirect effects via psychological distress were only found in males for the impact of rMSSD on CPT, the impact of SDNN on CPT, and the impact of BRS on CPT via psychological distress. Moderated mediation analyses revealed that there were no significant sex differences in the indirect effects of HRV and BRS on both CPT and CPI via psychological distress.

Conclusions:

The hypoalgesic impact of cardiovascular regulatory systems on evoked pain responses is conveyed via the indirect effects of psychological distress.

Stress and the baroreflex

The stress response to emotions elicits the release of glucocorticoids from the adrenal cortex, epinephrine from the adrenal medulla, and norepinephrine from the sympathetic nerves. The baroreflex adapts to buffer these responses to ensure that perfusion to the organs meets the demands while maintaining blood pressure within a within a narrow range. While stressor-evoked autonomic cardiovascular responses may be adaptive for the short-term, the recurrent exaggerated cardiovascular stress reactions can be maladaptive in the long-term. Prolonged stress or loss of the baroreflex's buffering capacity can predispose episodes of heightened sympathetic activity during stress leading to hypertension, tachycardia, and ventricular wall motion abnormalities. This review discusses 1) how the baroreflex responds to acute and chronic stressors, 2) how lesions in the neuronal pathways of the baroreflex alter the ability to respond or counteract the stress response, and 3) the techniques to assess baroreflex sensitivity and stress responses. Evidence suggests that loss of baroreflex sensitivity may predispose heightened autonomic responses to stress and at least in part explain the association between stress, mortality and cardiovascular diseases.

Development of Autonomic Nervous System Assays as Point-of-Care Tests to Supplement Clinical Judgment in Risk Assessment for Suicidal Behavior: A Review

PURPOSE OF REVIEW

A biomarker point-of-care (POC) test that supplements the psychiatric interview and improves detection of patients at risk for suicide would be of value, and assays of autonomic nervous system (ANS) activity would satisfy the logistical requirements for a POC test. We performed a selective review of the available literature of ANS assays related to risk for suicide.

RECENT FINDINGS

We searched PubMed and Web of Science with the strategy: "suicide OR suicidal" AND "electrodermal OR heart rate variability OR pupillometry OR pupillography." The search produced 119 items, 21 of which provided original data regarding ANS methods and suicide. These 21 studies included 6 for electrodermal activity, 14 for heart rate variability, and 1 for the pupillary light reflex. The 21 papers showed associations between ANS assays and suicide risk in a direction suggesting underlying hyperarousal in patients at risk for suicide. ANS assays show promise for future development as POC tests to supplement clinical decision making in estimating risk for suicide.

Eye pupil – a window into central autonomic regulation via emotional/cognitive processing

If the eyes are windows into the soul, then the pupils represent at least the gateway to the brain and can provide a unique insight into the human mind from several aspects. The changes in the pupil size primarily mediated by different lighting conditions are controlled by the autonomic nervous system regulated predominantly at the subcortical level. Specifically, parasympathetically-linked pupillary constriction is under the Edinger-Westphal nucleus control and sympathetically-mediated pupillary dilation is regulated from the posterior hypothalamic nuclei. However, the changes in the pupil size can be observed at resting state even under constant lighting, these pupillary changes are mediated by global arousal level as well as by various cognitive factors. In this context, autonomic pathways modulating changes in the pupil size in response to the different light levels can be influenced by multiple central descending inputs driving pupillary changes under steady lighting conditions. Moreover, as the pupillary response is involved in emotional (task-evoked pupillary dilation as an index of emotional arousal) and cognitive (task-evoked pupillary dilation as an index of cognitive workload) stimulation, it can be used to detect the impact of mutual subcortical and cortical structures (i.e. overlapping brain structures included in autonomic, emotional and cognitive regulation) on the pupillary innervation system. Thus, complex understanding of the baseline pupil size´ and pupillary dynamics´ mechanisms may provide an important insight into the central nervous system functioning pointing to the pupillometry as a promising tool in the clinical application.

Eye pupil - a window into central autonomic regulation via emotional/cognitive processing

If the eyes are windows into the soul, then the pupils represent at least the gateway to the brain and can provide a unique insight into the human mind from several aspects. The changes in the pupil size primarily mediated by different lighting conditions are controlled by the autonomic nervous system regulated predominantly at the subcortical level. Specifically, parasympathetically-linked pupillary constriction is under the Edinger-Westphal nucleus control and sympathetically-mediated pupillary dilation is regulated from the posterior hypothalamic nuclei. However, the changes in the pupil size can be observed at resting state even under constant lighting, these pupillary changes are mediated by global arousal level as well as by various cognitive factors. In this context, autonomic pathways modulating changes in the pupil size in response to the different light levels can be influenced by multiple central descending inputs driving pupillary changes under steady lighting conditions. Moreover, as the pupillary response is involved in emotional (task-evoked pupillary dilation as an index of emotional arousal) and cognitive (task-evoked pupillary dilation as an index of cognitive workload) stimulation, it can be used to detect the impact of mutual subcortical and cortical structures (i.e. overlapping brain structures included in autonomic, emotional and cognitive regulation) on the pupillary innervation system. Thus, complex understanding of the baseline pupil size´ and pupillary dynamics´ mechanisms may provide an important insight into the central nervous system functioning pointing to the pupillometry as a promising tool in the clinical application.

The skin conductance response indicating pain relief is independent of self or social influence on pain

Pain relief is defined as the ease of pain and is thus highly relevant for clinical applications and everyday life. Given that pain relief is based on the cessation of an aversive pain experience, it is reasonable to assume that pain relief learning would also be shaped by factors that alter subjective and physiological pain responses, such as social presence or a feeling of control. To date, it remains unclear whether and how factors that shape autonomic pain responses might affect pain relief learning. Here, we investigated how pain relief learning is shaped by two important factors known to modulate pain responses, i.e. social influence and controllability of pain. Skin conductance responses (SCRs) were recorded while participants learned to associate a formerly neutral stimulus with pain relief under three different pain conditions. In the social‐influence condition (N = 34), the pain stimulation could be influenced by another person’s decisions. In the self‐influence condition (N = 31), the participants themselves could influence the pain stimulation. Finally, in the no‐influence condition (N = 32), pain stimulation was simply delivered without any influence. According to our results, the SCRs elicited by the stimulus that was associated with pain relief were significantly smaller compared to the SCRs elicited by a neutral control stimulus, indicating pain relief learning. However, there was no significant difference in the pain relief learning effect across the groups. These results suggest that physiological pain relief learning in humans is not significantly influenced by social influence and pain controllability.

The contents of this page will be shown on the eTOC on the online version only. It will not be published as part of the article PDF. Subjective and physiological pain responses can be altered by social support or pain controllability. Pain relief strongly depends on the perceived pain, but we found that it is less influenceable. Neither social nor self‐influence changed the magnitude of physiological pain‐relief responses. We conclude that pain relief is a basic mechanism not easily influenced by circumstantial manipulations.

Heart Rate Variability Changes in Patients With Major Depressive Disorder: Related to Confounding Factors, Not to Symptom Severity?

Background

The aim of this study was to assess the electrophysiological and other influencing factors correlating with symptom severity in patients with major depressive disorder (MDD) under three different conditions: baseline, stress exposure, and relaxation following stress exposure.

Methods

Symptom severity was assessed using the Beck Depression Inventory (BDI-II) in 89 inpatients (37 women; mean age 51 years) with MDD. Resting heart rate (RHR), heart rate variability (HRV), respiration rate (RR), skin conductance (SC), and skin temperature (ST) were recorded at baseline for 300 s, under stress exposure for 60 s, and under self-induced relaxation for 300 s. Age, nicotine consumption, body mass index, and blood pressure were evaluated as influencing factors.

Results

The BDI-II mean score was 29.7 points. Disease severity correlated positively with SC elevation under stress exposure and with a higher RR in the relaxed state, but no association was found between HRV and symptom severity. Age and higher blood pressure were both associated with lower HRV and higher RHR.

Conclusion

The results indicate that, in patients with MDD, changes in the autonomic nervous system (ANS) are complex; and the assessment of ANS reactivity to stressors is useful. Elevated blood pressure might be underdiagnosed, although it is already relevant in patients with MDD in their early 50s.

Pupil Dilation during Reward Anticipation Is Correlated to Depressive Symptom Load in Patients with Major Depressive Disorder

Depression is a debilitating disorder with high prevalence and socioeconomic cost, but the brain-physiological processes that are altered during depressive states are not well understood. Here, we build on recent findings in macaques that indicate a direct causal relationship between pupil dilation and anterior cingulate cortex mediated arousal during anticipation of reward. We translated these findings to human subjects with concomitant pupillometry/fMRI in a sample of unmedicated participants diagnosed with major depression and healthy controls. We could show that the upregulation and maintenance of arousal in anticipation of reward was disrupted in patients in a symptom-load dependent manner. We could further show that the failure to maintain reward anticipatory arousal showed state-marker properties, as it tracked the load and impact of depressive symptoms independent of prior diagnosis status. Further, group differences of anticipatory arousal and continuous correlations with symptom load were not traceable only at the level of pupillometric responses, but were mirrored also at the neural level within salience network hubs. The upregulation and maintenance of arousal during reward anticipation is a novel translational and well-traceable process that could prove a promising gateway to a physiologically informed patient stratification and targeted interventions.

Implementing Mobile HRV Biofeedback as Adjunctive Therapy During Inpatient Psychiatric Rehabilitation Facilitates Recovery of Depressive Symptoms and Enhances Autonomic Functioning Short-Term: A 1-Year Pre-Post-intervention Follow-Up Pilot Study

OBJECTIVE

New treatment options for depression are warranted, due to high recurrence rates. Recent research indicates benefits of heart rate variability biofeedback (HRVBF) on symptom recovery and autonomic functioning in depressed individuals. Slow-paced breathing-induced amplification of vagus nerve activity is the main element of HRVBF. Thus, the latter represents a safe and non-invasive complementary depression treatment. However, its efficacy in patients undergoing inpatient psychiatric rehabilitation receiving highly comprehensive treatments has not been evaluated.

METHODS

Ninety-two inpatients were randomly assigned to an intervention group (IG) or control group (CG). While the latter received the standard treatment only, adjunctive HRVBF was provided to the IG over 5 weeks. Depression severity and heart rate variability (HRV) were assessed before (pre) and after 5 weeks (post). Moreover, 1-year follow-up depression scores were available for 30 participants.

RESULTS

Although depression improved in both groups, the IG exhibited significantly larger improvements at post-assessment ( η p 2 = 0.065) and significant increases in resting LF-HRV (d = 0.45) and cardiorespiratory coherence (d = 0.61). No significant effects for RMSSD, SDNN, HF-HRV, or HR were found (ps > 0.05). Additionally, the IG showed a medium- to large-sized reduction in resting respiratory rate from 13.2 to 9.8 breaths per minute (p < 0.001, d = 0.86), with the CG exhibiting only a small decrease from 13.5 to 12.4 (p = 0.49; d = 0.35). While the IG exhibited significantly lower depression scores at post-assessment (p = 0.042, d = 0.79), this effect decreased during follow-up (p = 0.195, d = 0.48).

CONCLUSION

HRVBF as adjuvant therapy during inpatient psychiatric rehabilitation facilitated depression recovery. Additionally, amplified LF-HRV as well as cardiorespiratory coherence at rest and a decrease in resting breathing frequency was observed in the HRVBF group. These findings emphasize HRVBF's value as complementary therapy regardless of concurrent treatments. Moreover, these incremental benefits could serve as resource even after the actual training period. However, the additional antidepressant gains vanish during the long-term follow-up, indicating the need for more intense training or regular practice afterward, respectively. Thus, future studies are warranted to examine how the initial benefits of HRVBF during inpatient psychiatric rehabilitation can be preserved post discharge.

Features of autonomic cardiovascular control during cognition in major depressive disorder

Previous research has suggested reduced parasympathetic cardiac regulation during cognitive activity in major depressive disorder (MDD). However, little is known about possible abnormalities in sympathetic control and cardiovascular reactivity. This study aimed to provide a comprehensive analysis of autonomic cardiovascular control in the context of executive functions in MDD. Thirty six MDD patients and 39 healthy controls participated. Parameters of sympathetic (pre-ejection period, PEP) and parasympathetic control (high and low frequency heart rate variability, HF HRV, LF HRV; and baroreflex sensitivity, BRS) as well as RR interval were obtained at rest and during performance of executive function tasks (number-letter task, n-back task, continuous performance test, and Stroop task). Patients, as compared to controls, exhibited lower HF HRV and LF HRV during task execution and smaller shortenings in PEP and RR interval between baseline and tasks. They displayed longer reaction times during all conditions of the tasks and more omission errors and false alarms on the continuous performance test. In the total sample, on-task HF HRV, LF HRV and BRS, and reactivity in HF HRV, LF HRV, and PEP, were positively associated with task performance. As performance reduction arose independent of executive function load of the tasks, the behavioral results reflect impairments in attention and processing speed rather than executive dysfunctions in MDD. Abnormalities in cardiovascular control during cognition in MDD appear to involve both divisions of the autonomic nervous system. Low tonic parasympathetic control and blunted sympathetic reactivity imply reduced physiological adjustment resources and, by extension, provide suboptimal conditions for cognitive performance.

The role of physical activity in the association between multimorbidity and depressive symptoms: Data from 60,202 adults from the Brazilian National Health Survey

OBJECTIVE

Depression is commonly associated to physical multimorbidity and there is an urgent need to identify modifiable risk factors. Physical activity (PA) is good for health, but the association between PA and multimorbidity with depressive symptoms is unclear. Thus, we investigated whether meeting weekly recommended PA guidelines influences the association between multimorbidity and depressive symptoms.

METHODS

Data were used from a national survey conducted in Brazil in 2013 with 60,202 adults (≥ 18 years). Information regarding depressive symptoms (PHQ-9), PA, and chronic disease was collected via interview-administered questionnaires. Data on covariates (age, educational status, employment status, tobacco smoking, alcohol consumption, and TV-viewing) were also assessed. Adjusted logistic regression models were used.

RESULTS

Overall, men and women with one or more chronic conditions who were inactive (engaging in <150 min PA per week) had higher odds of elevated depressive symptoms than active individuals with no chronic condition. However, only in men, physical inactivity interacts with heart disease (OR: 2.59; 95%CI: 1.10 to 6.09), cancer (OR: 21.54; 95%CI: 2.67 to 173.94) and chronic obstructive pulmonary disease (COPD) (OR: 8.26; 95%CI: 2.20 to 31.01) regarding elevated depressive symptoms.

CONCLUSION

Our data suggest that engaging in weekly recommended PA targets may attenuate association of heart disease, cancer and COPD with depressive symptoms among men.

Does physical activity influence the association between depressive symptoms and low-grade inflammation in adults? A study of 8,048 adults

This study investigated whether physical activity (PA) influences the association between depression risk and low-grade inflammation. This was a cross-sectional study including 8,048 adults (18-59y). Depression symptoms were evaluated with the Beck depression inventory (BDI) and physical activity through the international physical activity questionnaire. Adults with infectious and inflammatory diseases were excluded. Blood samples were collected, including high sensitivity C-reactive protein (CRP), a marker of low-grade inflammation when ≥3mg/L. Additional measures of LDL-C, HDL-C, triglycerides and fasting glucose were also determined. Sex, chronological age, tobacco smoking, alcohol drinking, body mass index, dyslipidemia, high blood pressure and fasting glucose were used as covariates. Mediation models were conducted using the procedures of Karlson Holm Breen. Adults with elevated CRP (≥3mg/L) compared to those with low CRP (<3mg/L) presented with higher BDI scores [8.5%(95%CI:7.2%-10.1%) vs. 5.8%(95%CI:5.2-6.4)] as well as higher prevalence of physical inactivity 67.4% (95%CI:64.9-69.9) vs. 59.7% (95%CI:58.4-60.9). The prevalence of elevated CRP was highest in physically inactive adults with greater depression risk. Models revealed that physical activity risk explained 13% of the association between depression risk and elevated CRP (p=0.035), independently of potential confounders. Physical activity may reduce the association between depression symptoms and elevated CRP. Future longitudinal research is required to determine the directionality of the relationships observed.

Exploring Key Physiological System Profiles at Rest and the Association with Depressive Symptoms in Autism Spectrum Disorder

Depression is often associated with dysfunction in the hypothalamic-pituitary-adrenal (HPA) axis and autonomic nervous system (ANS). Individuals with autism spectrum disorder (ASD) may experience physiological dysregulation and psychological comorbidities; however, the extent to which the interactions between these systems predict internalizing symptoms in ASD has not been investigated. The study examined interactions with the HPA axis and ANS in 10-13-year-old children with ASD (n = 41) and typical development (TD; n = 46). The interrelated systems uniquely contributed to depressive symptoms in ASD above and beyond any system in isolation. A reciprocal, parasympathetic-dominant ANS was related to fewer affective symptoms in ASD. Findings highlight the importance of examining arousal across multiple systems to more precisely identify profiles associated with maladaptive psychiatric outcomes in ASD.

Sympathetic and Parasympathetic Modulation of Pupillary Unrest

Pupillary unrest is an established indicator of drowsiness or sleepiness. How sympathetic and parasympathetic activity contribute to pupillary unrest is not entirely unclear. In this study, we investigated 83 young healthy volunteers to assess the relationship of pupillary unrest to other markers of the autonomic nervous system. Sample entropy (SE) and the established pupillary unrest index (PUI) were calculated to characterize pupil size variability. Autonomic indices were derived from heart rate, blood pressure, respiration, and skin conductance. Additionally, we assessed individual levels of calmness, vigilance, and mood. In an independent sample of 26 healthy participants, we stimulated the cardiovagal system by a deep breathing test. PUI was related to parasympathetic cardiac indices and sleepiness. A linear combination of vagal heart rate variability [root mean square of heart beat interval differences (RMSSD)] and skin conductance fluctuations (SCFs) was suited best to explain interindividual variance of PUI. Complexity of pupil diameter (PD) variations correlated to indices of sympathetic skin conductance. Furthermore, we found that spontaneous fluctuations of skin conductance are accompanied by increases of pupil size. In an independent sample, we were able to corroborate the relation of PUI with RMSSD and skin conductance. A slow breathing test enhanced RMSSD and PUI proportionally to each other, while complexity of PD dynamics decreased. Our data suggest that the slow PD oscillations (f < 0.15 Hz) quantified by PUI are related to the parasympathetic modulation. Sympathetic arousal as detected by SCFs is associated to transient pupil size increases that increase non-linear pupillary dynamics.

Application of heart rate variability during blood pressure measurement in patients with somatic symptom disorder

OBJECTIVE

This study wants to test whether the heart rate variability (HRV) analysis using sphygmomanometers can effectively reflect the physical and emotional distress of somatic symptom disorder (SSD) cases and assist in further health management.

METHODS

This study includes 66 female SSD cases and 32 male SSD cases. All cases received a 200-second blood pressure (BP) measurement, after which the numerical figure for the heart rate was obtained from the BP signal for HRV analysis. All cases also filled out Patient Health Questionnaire-15 (PHQ-15), Beck Depression Inventory-II (BDI-II), Beck Anxiety Inventory (BAI) to understand the extent of their somatic distress, depression, and anxiety. The relationship between psychological conditions and HRV indicators are examined statistically. Receiver operating characteristic (ROC) curve analysis was used to understand whether HRV indicators can assist in the determination of psychosomatic problems.

RESULTS

Considering all and female SSD cases, low-frequency power (LF) and PHQ-15 in the HRV index have the most significant correlations. In male SSD cases, root mean square of successive NN interval differences (RMSSD) and BDI-II have the highest correlations. The results of ROC curve analysis indicate that LF is useful to judge the severity of female SSD cases, while RMSSD has reference value in determining whether male patients of SSD cases have depression or not. In addition, physical stress index (PSI) can also help determine the degree of depression in male SSD cases.

CONCLUSION

The use of BP in HRV analysis can help in the monitoring of somatic distress and depression issues in SSD cases. LF, RMSSD, PSI are potential physiological indicators.

Entropy analysis of heart rate variability and its application to recognize major depressive disorder: A pilot study

BACKGROUND

The current method to evaluate major depressive disorder (MDD) relies on subjective clinical interviews and self-questionnaires.

OBJECTIVE

Autonomic imbalance in MDD patients is characterized using entropy measures of heart rate variability (HRV). A machine learning approach for screening depression based on the entropy is demonstrated.

METHODS

The participants experience five experimental phases: baseline (BASE), stress task (MAT), stress task recovery (REC1), relaxation task (RLX), and relaxation task recovery (REC2). The four entropy indices, approximate entropy, sample entropy, fuzzy entropy, and Shannon entropy, are extracted for each phase, and a total of 20 features are used. A support vector machine classifier and recursive feature elimination are employed for classification.

RESULTS

The entropy features are lower in the MDD group; however, the disease does not have a significant effect. Experimental tasks significantly affect the features. The entropy did not recover during REC1. The differences in the entropy features between the two groups increased after MAT and showed the largest gap in REC2. We achieved 70% accuracy, 64% sensitivity, and 76% specificity with three optimal features during RLX and REC2.

CONCLUSION

Monitoring of HRV complexity changes when a subject experiences autonomic arousal and recovery can potentially facilitate objective depression recognition.

The Association Between Juvenile Onset of Depression and Emotion Regulation Difficulties

Juvenile onset of Major Depressive Disorder (MDD) is associated with increased likelihood of recurrent episodes of depression and more detrimental clinical trajectories. The aim of the current study was to investigate the effect of juvenile onset of MDD on emotion regulation as measured by self-report and Heart Rate Variability (HRV). Furthermore, we wanted to assess whether juvenile onset impacted the association between rumination and depressive symptoms. Sixty-four individuals with at least three prior episodes of MDD were recruited and filled out self-report questionnaires measuring rumination and emotion regulation abilities. In addition, electrocardiographic assessments were used to calculate HRV. Based on self-reported age of MDD onset, individuals were divided in two groups: Juvenile onset of MDD (first MDD episode before the age of 18, n = 30) and adult onset of MDD (first MDD episode after the age of 18, n = 34). Results showed that individuals whose first depressive episode occurred in childhood and adolescence reported more rumination and less emotional clarity compared to individuals who had their first episode of MDD in adulthood. Moreover, the tendency to ruminate was strongly associated with depressive symptoms in the juvenile onset of MDD group, whereas no such association was found in the adult onset group. There was no significant group difference for HRV. The findings are discussed in light of existing literature, in addition to suggesting how our findings may inform clinical practice and future research. We conclude that juvenile onset of MDD may lead to difficulties in emotion regulation and that these difficulties may increase depressive symptoms and vulnerability for relapse in this particular subgroup.

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.

Heart rate variability as a biomarker in health and affective disorders: A perspective on neuroimaging studies

The dynamic embodiment of psychological processes is evident in the association of health outcomes, behavioural traits and psychological functioning with Heart Rate Variability (HRV). The dominant high-frequency component of HRV is an index of the central neural control of heart rhythm, mediated via the parasympathetic vagus nerve. HRV provides a potential objective measure of action policies for the adaptive and predictive allostatic regulation of homeostasis within the cardiovascular system. In its support, a network of brain regions (referred to as the 'central autonomic network') maps internal state, and controls autonomic responses. This network includes regions of prefrontal cortex, anterior cingulate cortex, insula, amygdala, periaqueductal grey, pons and medulla. Human neuroimaging studies of neural activation and functional connectivity broadly endorse this architecture, and its link with cardiac regulation at rest and dysregulation in clinical states that include affective disorders. In this review, we appraise neuroimaging research and related evidence for HRV as an informative marker of autonomic integration with affect and cognition, taking a perspective on function and organisation. We consider evidence for the utility of HRV as a metric to inform targeted interventions to improve autonomic and affective dysregulation, and suggest research questions for further investigation.

Depressive symptoms and immune transcriptional profiles in late adolescents

BACKGROUND

Rates of depression increase and peak during late adolescence and alterations in immune processes are thought to be both a risk factor and outcome of depression. However, few studies have examined depression-immune dynamics among adolescents. Using a functional genomics approach, the current study examined whether depressive symptoms were associated with activation of a gene expression profile, characterized by upregulated expression of pro-inflammatory-related genes and downregulated expression of antiviral-related genes in a sample of older adolescents (M_age = 18.37, SD = 0.51).

METHOD

Participants (n = 87) reported on their depressive symptoms during the past week using the CES-D, and provided blood samples for genome-wide transcriptional profiling of mRNA.

RESULTS

Adolescents with clinically-significant levels of depressive symptoms (CES-D ≥ 16) exhibited upregulated expression of inflammation-related genes and downregulated expression of antiviral-related genes compared to their peers with lower levels of depressive symptoms (CES-D < 16). Bioinformatics analyses suggested that this pattern of differential gene expression was mediated by greater activity of the pro-inflammatory transcription factor, nuclear factor-kappa B (NF-κB), and reduced activity of glucocorticoid receptors (GRs) and interferon response factors (IRFs). Additional analyses implicated monocytes, B cells, and dendritic cells as primary cellular sources of the observed gene expression patterns associated with depressive symptoms.

CONCLUSION

Results are consistent with past work demonstrating links between depression and altered immunity. They provide a molecular basis for these associations and suggest that the underlying molecular signature may emerge as early as late adolescence when rates of depression tend to increase.

The relationship between heart rate and functional connectivity of brain regions involved in autonomic control

The peripheral autonomic nervous system (ANS) adjusts the heart rate (HR) to intrinsic and extrinsic demands. It is controlled by a group of functionally connected brain regions assembling the so-called central autonomic network (CAN). More specifically, forebrain cortical regions, limbic and brainstem structures within the CAN have been identified as important components of circuits involved in HR regulation. The present study aimed to investigate whether functional connectivity (FC) between these regions varies in subjects with different heart rates. Thus, 84 healthy subjects were separated according to their HR in slow, medium and fast. We observed a direct association between HR and FC in CAN regions, where stronger FC was related to slower HR. This relationship, however, is non-linear, follows an exponential course and is not restricted to CAN areas only. The network-based analysis (NBS) using time series from 262 independent anatomical ROIs revealed significantly increased functional connectivity in subjects with slow HR compared to subjects with fast HR mainly in regions being part of the salience network, but also of the default-mode network. We additionally simulated the effect of aliasing on the functional connectivity using several TRs and heart rates to exclude the possibility that FC differences might be due to different aliasing effects in the data. The result of the simulation indicated that aliasing cannot explain our findings. Thus, present results imply a functionally meaningful coupling between FC and HR that need to be accounted for in future studies. Moreover, given the established link between HR and emotional, cognitive and social processes, present findings may also be considered to explain individual differences in brain activation or connectivity when using corresponding paradigms in the MR scanner to investigate such processes.

Chronic pain-related changes in cardiovascular regulation and impact on comorbid hypertension in a general population: the Tromsø study

Heart rate variability (HRV) and baroreflex sensitivity (BRS) are indexes reflecting the ability to maintain cardiovascular homeostasis amidst changing conditions. Evidence primarily from small studies suggests that both HRV and BRS may be reduced in individuals with chronic pain (CP), with potential implications for cardiovascular risk. We compared HRV and BRS between individuals with CP (broadly defined) and pain-free controls in a large unselected population sample. Participants were 1143 individuals reporting clinically meaningful CP and 5640 pain-free controls who completed a 106-second cold pressor test (CPT). Participants self-reported hypertension status. Resting HRV and BRS were derived from continuous beat-to-beat blood pressure recordings obtained before and after the CPT. Hierarchical regressions for the pre-CPT period indicated that beyond effects of age, sex, and body mass index, the CP group displayed significantly lower HRV in both the time domain (SDNN and rMSSD) and frequency domain (high-frequency HRV power), as well as lower BRS. Results were somewhat weaker for the post-CPT period. Mediation analyses indicated that for 6 of 7 HRV and BRS measures tested, there were significant indirect (mediated) effects of CP status on the presence of comorbid hypertension via reduced HRV or BRS. Results confirm in the largest and broadest sample tested to date that the presence of CP is linked to impaired cardiovascular regulation and for the first time provide support for the hypothesis that links between CP and comorbid hypertension reported in previous population studies may be due in part to CP-related decrements in cardiovascular regulation.

Brain structural thickness and resting state autonomic function in adolescents with major depression

Major depressive disorder (MDD) has been associated with abnormalities in cortical thickness and autonomic function. Adolescence is a time notable for brain development and MDD onset. In healthy adolescents, greater resting state vagal activity (RVA) is associated with lower cortical thickness. The relationship between brain structural thickness and RVA in adolescents with MDD has not previously been studied. This secondary analysis drew on a sample of 37 non-depressed controls and 53 adolescents with MDD. Resting state heart rate and two indices of RVA (HF-HRV and RMSSD) were recorded during a neuroimaging session. Cortical thickness within fronto-limbic regions of interest was measured using Freesurfer analysis of T1-weighted high-resolution structural images. Self-reports of depression severity showed a significant interaction with cortical thickness of the right insula in predicting RMSSD [t = 2.22, P=0.030, β = 5.44; model fit of the interaction term as indicated by the ‘Bayes Factor’ (BF): 7.58] and HF-HRV (t = 2.09, P=0.041, β = 4.72; BF: 7.94). Clinician ratings of depression severity showed further interactions. Findings underscore the important relationships between RVA and cortical development, suggesting two possible explanations: (i) in adolescent MDD, greater fronto-limbic thickness is compensatory for deficits in autonomic regulation or (ii) increased autonomic arousal results in delayed fronto-limbic maturation. Longitudinal research is necessary to further clarify the nature of the relationship between autonomic functioning and cortical development.

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.

Heart Rate Variability as Indicator of Clinical State in Depression

Background: Depression is a severe disease with great burdens for the affected individuals and public health care systems. Autonomic nervous system (ANS) dysfunction indexed by measures of heart rate variability (HRV) has repeatedly been associated with depression. However, HRV parameters are subject to a wide range of multi-factorial influences and underlying mechanisms in depression are still unclear. HRV parameters have been proposed to be promising candidates for diagnostic or predictive bio-markers for depression but necessary longitudinal design studies investigating the relationship between HRV and depression are scarce. Methods: The sample in this study consisted of 62 depressive individuals without antidepressant medication prior to assessment and 65 healthy controls. Fifteen minute blocks of resting ECGs were recorded 1-2 days before onset of antidepressant treatment and 2 weeks thereafter. The ECGs were pre-processed to extract inter-beat-intervals. Linear and non-linear methods were used to extract HRV parameters. ANOVAS were performed to investigate group differences between depressive patients and healthy controls. Associations between the change in severity of depression and HRV parameters were assessed in a repeated measurements design. Results: Analyses revealed HRV parameter differences between the groups of depressive patients and healthy controls at baseline. Further results show differences in HRV parameters within subjects after 2 weeks of antidepressant treatment. Change in HRV parameter values correlated with changes in symptom severity of depression. Discussion: The current results provide further insight into the relationship between HRV parameters and depression. This may help to underpin utilization of HRV parameters are bio-maker for disease state in depression. Results are discussed within a theoretical framework to link arousal and ANS regulation in depression.