Heart rate variability and suicidal behavior

From Social Stress and Isolation to Autonomic Nervous System Dysregulation in Suicidal Behavior

PURPOSE OF REVIEW

In this narrative review we wanted to describe the relationship of autonomic nervous system activity with social environment and suicidal spectrum behaviors.

RECENT FINDINGS

Patients with suicidal ideation/suicide attempt have higher sympathetic nervous system (SNS) and lower parasympathetic nervous system (PNS) activity in resting conditions and during acute stress tasks compared with patients without suicidal ideation/suicide attempt. Death by suicide and violent suicide attempt also are related to SNS hyperactivation. Similarly, a SNS/PNS imbalance has been observed in people with childhood trauma, stressful life events or feelings of loneliness and isolation. Social support seems to increase PNS control and resilience. Due to the importance of the social context and stressful life events in suicidal behavior, SNS/PNS imbalance could act as a mediator in this relationship and be a source of relevant biomarkers. Childhood trauma and stressful life events may impair the autonomic nervous system response in suicidal patients. Loneliness, isolation and social support may act as moderators in acute stress situations.

Self- and co-regulation of physiological activity during mother-daughter interactions: The role of adolescent non-suicidal self-injury

BACKGROUND

Non-suicidal self-injury (NSSI) is a significant public health concern that is thought to increase risk for future self-injurious behaviors, including suicide attempts. Notably, NSSI is especially prevalent among adolescents, which underscores a critical need to identify modifiable risk factors that could be targeted to reduce future risk. The current study examined self- and co-regulation of physiological responses during mother-daughter interactions in adolescent girls with and without a history of NSSI.

METHODS

Participants were 60 girls aged 13-17 with (n = 27) and without (n = 33) a history of NSSI and their mothers. Adolescents and their mothers completed positive and negative interaction tasks during which physiological reactivity was assessed via respiratory sinus arrhythmia (RSA).

RESULTS

Using Actor-Partner Interdependence Modeling (APIM), we found that adolescents with an NSSI history demonstrated a higher RSA setpoint than adolescents without this history during the negative, but not positive, interaction task. In addition, there were differences in co-regulation during the negatively valenced interaction, such that mothers of daughters with NSSI were more reactive to fluctuations in their daughters' RSA than mothers of daughters without an NSSI history.

CONCLUSIONS

These findings highlight intra- and interpersonal aspects of physiological dysregulation associated with NSSI that could provide promising targets of intervention to reduce future risk in adolescent girls.

Child maltreatment and youth suicide risk: A developmental conceptual model and implications for suicide prevention

Experiences of child abuse and neglect are risk factors for youth suicidal thoughts and behaviors. Accordingly, suicide risk may emerge as a developmental process that is heavily influenced by the rearing environment. We argue that a developmental, theoretical framework is needed to guide future research on child maltreatment and youth (i.e., adolescent and emerging adult) suicide, and to subsequently inform suicide prevention efforts. We propose a developmental model that integrates principles of developmental psychopathology and current theories of suicide to explain the association between child maltreatment and youth suicide risk. This model bears significant implications for future research on child maltreatment and youth suicide risk, and for suicide prevention efforts that target youth with child maltreatment experiences.

Respiratory sinus arrhythmia, negative social interactions, and fluctuations in unmet interpersonal needs: A daily diary study

INTRODUCTION

This study examined daily fluctuations in the unmet interpersonal needs of thwarted belongingness and perceived burdensomeness in response to daily negative social interactions, as well as the moderating role of respiratory sinus arrhythmia (RSA) across adolescents at lower and higher risk for suicidal ideation.

METHODS

Fifty five adolescents with major depressive disorder (MDD, i.e., higher-risk group) and without MDD (i.e., lower-risk group) completed measures of resting RSA, and daily measures of negative social interactions, perceived burdensomeness, and loneliness, as a proxy for thwarted belongingness, for 10 consecutive days. Within-person analyses examined the association between daily negative social interactions and unmet interpersonal needs, and the moderating roles of RSA and higher-risk group status. Between-person analyses also examined the association between RSA and unmet interpersonal needs across groups.

RESULTS

At the within-person level, participants reported more unmet interpersonal needs on days when they reported more negative social interactions. At the between-person level, higher RSA was associated with decreased loneliness in both groups, and decreased burdensomeness among the higher-risk group.

CONCLUSIONS

Negative social interactions are associated with daily unmet interpersonal needs. Higher RSA may serve as a protective factor mitigating risk for unmet interpersonal needs, particularly burdensomeness, among adolescents at higher risk for suicidal ideation.

Resting State EEG Correlates of Suicide Ideation and Suicide Attempt

Suicide is a global phenomenon that impacts individuals, families, and communities from all income groups and all regions worldwide. While it can be prevented if personalized interventions are implemented, more objective and reliable diagnostic methods are needed to complement interview-based risk assessments. In this context, electroencephalography (EEG) might play a key role. We systematically reviewed EEG resting state studies of adults with suicide ideation (SI) or with a history of suicide attempts (SAs). After searching for relevant studies using the PubMed and Web of Science databases, we applied the PRISMA method to exclude duplicates and studies that did not match our inclusion criteria. The selection process yielded seven studies, which suggest that imbalances in frontal and left temporal brain regions might reflect abnormal activation and correlate with psychological distress. Furthermore, asymmetrical activation in frontal and posterior cortical regions was detected in high-risk depressed persons, although the pattern in the frontal region was inverted in non-depressed persons. The literature reviewed suggests that SI and SA may be driven by separate neural circuits and that high-risk persons can be found within non-depressed populations. More research is needed to develop intelligent algorithms for the automated detection of high-risk EEG anomalies in the general population.

A recent suicide attempt and the heartbeat: Electrophysiological findings from a trans-diagnostic cohort of patients and healthy controls

Suicidal behavior is influenced by a multitude of factors, making prediction and prevention of suicide attempts (SA) a challenge. A useful tool to uncover underlying pathophysiology or propose new therapy approaches are biomarkers, especially within the context of point-of-care tests. Heart rate variability (HRV) is a well-established biomarker of mental health, and measures the activity of the sympathetic and parasympathetic nervous system (PNS). Previous studies reported a correlation between lower PNS activity and suicidality. However, most studies involved participants from a healthy population, patients without history of suicide attempts, or patients with a single diagnosis. 52 in-patients with a recent suicide attempt (<6 months), and 43 controls without history of SA or psychiatric diagnoses confirmed study participation. The included patients age ranged between 18 and 65 years, 65% had psychiatric comorbidities. Patients with dementia, cognitive impairments, acute psychosis, chronic non suicidal self-harming behavior, or current electroconvulsive therapy were excluded. A 15-min resting state electrocardiography was recorded with two bipolar electrodes attached to the right and left insides of the wrists. The multiple regression analyses showed lower parasympathetic, and higher sympathetic activity in patients compared to controls. Partial correlation found a positive trend result between self-reported suicidality and the very low frequency band. ROC curve analysis revealed an acceptable to excellent clinical accuracy of HRV parameters. Therefore, HRV parameters could be reliable discriminative biomarkers between in-patients with a recent SA and healthy controls. One limitation is the lack of a control group consisting of in-patients without life-time suicidal ideation or attempts.

The impulsiveness level influences the salivary cortisol response and social stress sensitivity in suicidal patients

INTRODUCTION

Suicide attempters (SA) are more vulnerable to social stress and show disturbed cortisol response in stressful conditions compared with psychiatric and healthy controls. Recent data suggest that this dysregulation might be related to impulsivity traits. However, little is known about the emotional consequences of social stress in SA exposed to stress.

OBJECTIVES

The aim of our study was to evaluate the cortisol and emotional responses to social stress in patients with depression with and without suicide attempt, by taking into account impulsivity traits and depression severity.

METHODS

67 adult women (41 SA and 26 affective controls (AC,i.e. without suicide attempt history)) with lifetime history of major depressive episode were included. Patients performed the Trier Social Stress Test (TSST), a well-validated social stress task. Patients provided seven saliva samples, to measure the cortisol response, and filled in questionnaires to assess psychological pain, positive and negative mood, and anxiety at different time points (from 10 min before to 120 min after the TSST). Moderated regression models were used including suicide attempt history, depression severity, and impulsivity as independent variables and their interactions.

RESULTS

In patients with low depression and high impulsivity, salivary cortisol response during the TSST was higher in SA than in AC (p < .001). Psychological pain, negative mood, and anxiety were increased in all patients just after the TSST, followed by a decrease at 120 min. Positive mood recovery was slower in SA, and in patients with high impulsivity and low depression level (p < .001).

CONCLUSIONS

Impulsivity traits have an important role in suicidal vulnerability in stress conditions. Impulsivity traits might help to differentiate patients at risk of suicide who are highly sensitive to stress when depression level is low. Higher impulsiveness may increase the sensitivity to emotional distress that translates into inadequate physiological responses.

Utilizing digital predictive biomarkers to identify Veteran suicide risk

Veteran suicide is one of the most complex and pressing health issues in the United States. According to the 2020 National Veteran Suicide Prevention Annual Report, since 2018 an average of 17.2 Veterans died by suicide each day. Veteran suicide risk screening is currently limited to suicide hotlines, patient reporting, patient visits, and family or friend reporting. As a result of these limitations, innovative approaches in suicide screening are increasingly garnering attention. An essential feature of these innovative methods includes better incorporation of risk factors that might indicate higher risk for tracking suicidal ideation based on personal behavior. Digital technologies create a means through which measuring these risk factors more reliably, with higher fidelity, and more frequently throughout daily life is possible, with the capacity to identify potentially telling behavior patterns. In this review, digital predictive biomarkers are discussed as they pertain to suicide risk, such as sleep vital signs, sleep disturbance, sleep quality, and speech pattern recognition. Various digital predictive biomarkers are reviewed and evaluated as well as their potential utility in predicting and diagnosing Veteran suicidal ideation in real time. In the future, these digital biomarkers could be combined to generate further suicide screening for diagnosis and severity assessments, allowing healthcare providers and healthcare teams to intervene more optimally.

Associations of three major physiological stress systems with suicidal ideation and suicide attempts in patients with a depressive and/or anxiety disorder

BACKGROUND

People with depressive and/or anxiety disorders are at increased risk of suicidal ideation and suicide attempts, but biological correlates signaling such risk remain unclear. Independent and cumulative dysregulations in physiological stress systems, in particular the hypothalamic-pituitaryadrenal axis (HPA-axis), immune-inflammatory system, and autonomous nervous system (ANS), may contribute to this risk. However, findings have either been heterogeneous or absent thus far.

METHODS

Associations between individual markers and cumulative indices of the HPA-axis (cortisol awakening response and evening cortisol), immune-inflammatory system (C-reactive protein, interleukin-6 (IL-6), and tumor necrosis factor-α), and the ANS (heart rate, respiratory sinus arrhythmia, and pre-ejection period) and the outcomes no suicide ideation with suicide attempt (SI-SA+), suicide ideation without suicide attempt (SI+SA-) and suicide ideation with suicide attempt (SI+SA+) were investigated in 1749 persons with depressive and/or anxiety disorders from the Netherlands Study of Depression and Anxiety (NESDA).

RESULTS

High levels of CRP and IL-6 were associated with SI-SA+ and SI+SA+ respectively when compared to non-suicidal patients after adjusting for confounders and multiple testing. Also, cumulative immune-inflammatory dysregulations were positively associated with SI+SA+, suggesting a dose-response effect. No significant associations were found between HPA-axis or ANS indicators and suicide-outcomes and between immune-inflammatory system markers or cumulative stress system dysregulations and SI+SA-.

CONCLUSION

Although stress system markers could not differentiate between SI+SA- and non-suicidal patients, findings indicate that dysregulations of individual and cumulative immune-inflammatory markers are associated with suicide attempts in depressive and/or anxiety patients. Thus, immune-inflammatory system dysregulation may be involved in the pathophysiology of suicidal behavior, supporting further examination of the effects of anti-inflammatory interventions on suicidality.

Learning from gain and loss: Links to suicide risk

Despite preliminary evidence that people with suicide attempt histories demonstrate deficits in processing feedback, no studies have examined the interrelations of learning from feedback and emotional state on suicide risk. This study examined the influence of suicide risk and negative emotions on learning accuracy and rates among individuals with a range of borderline personality features (N = 145). Participants completed a reinforcement learning task after neutral and negative emotion inductions. Results revealed interactions between suicide risk and emotion condition, with elevated risk linked to greater increases in loss learning rate (training phase models) and gain learning rate (test phase models) post-negative emotion induction. Emotion-dependent fluctuations in learning performance may be markers of decision-making that are associated with greater suicide risk. This line of work has the potential to identify the contexts that confer greater risk for suicidal behaviors.

Emergency Department Adolescent Suicidality: A Pilot Study to Determine How Common Actual Attempts Are

OBJECTIVE

Adolescent mental health is a rapidly escalating presentation to emergency departments in the United States with depression and suicidal thoughts being the most prevalent condition. Much of the research and focus has been on preventing future attempts. However, one outcome that may be very important in addition to focus on is the impact of presentations for thoughts without self-injury. The aim was to evaluate outcomes of interest for a larger prospective observational adolescent suicidal trial including frequency of suicide attempts versus thoughts and factors associated with each outcome.

METHODS

This is a prospective pilot study of adolescents at a single pediatric emergency department between December 2016 and September 2017 with acute suicidality. We used descriptive statistics to compare chief complaint, medical history, Patient Health Questionnaire-9 (PHQ-9), and outcomes including final disposition and total emergency department length of stay (LOS). We used t tests for continuous outcomes, χ2 test for categorical data, and Fisher exact tests for categorical and sparse data (20% of cell sizes of <5).

RESULTS

Forty-one patients were enrolled, with 43.9% having an attempt; 72.2% of attempts were the result of an ingestion, and approximately 54% were over-the-counter medications. The average (SD) LOS was 30.8 (31.2) hours, and 63% were discharged home to outpatient services. There were no significant differences in age, chief complaint (except overdose), medical history, final disposition, total LOS in the ED, and the PHQ-9. Scores of the PHQ-9 were, on average (SD), 18.51 (4.7) across the entire cohort, 18.06 (5.75) in patients with an attempt, and 18.87 (3.77) in patients without an attempt (P = 0.59).

CONCLUSIONS

Adolescent mental health is a growing issue for pediatric emergency departments nationally. Prospective research to identify factors associated with worsening outcomes is important to identify and potentially modify if possible. This study did not find any specific factors associated with a suicide attempt, but found that less than half of patients presenting with suicidality actual made an attempt. Future research should focus on not only limiting suicide attempts but also using decreased emergency department visits for worsening thoughts as an outcome of interest.

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.

Digital Technologies for Emotion-Regulation Assessment and Intervention: A Conceptual Review

The ability to regulate emotions in response to stress is central to healthy development. While early research in emotion regulation predominantly employed static, self-report measurement, the past decade has seen a shift in focus toward understanding the dynamic nature of regulation processes. This is reflected in recent refinements in the definition of emotion regulation, which emphasize the importance of the ability to flexibly adapt regulation efforts across contexts. The latest proliferation of digital technologies employed in mental health research offers the opportunity to capture the state- and context-sensitive nature of emotion regulation. In this conceptual review, we examine the use of digital technologies (ecological momentary assessment; wearable and smartphone technology, physical activity, acoustic data, visual data, and geo-location; smart home technology; virtual reality; social media) in the assessment of emotion regulation and describe their application to interventions. We also discuss challenges and ethical considerations, and outline areas for future research.

Heart Rate Variability and Its Ability to Detect Worsening Suicidality in Adolescents: A Pilot Trial of Wearable Technology

OBJECTIVE

Suicide is the 2nd leading cause of death in adolescence, and acute pediatric mental health emergency department (ED) visits have doubled in the past decade. The objective of this study was to evaluate physiologic parameters relationship to suicide severity.

METHODS

This was a prospective, observational study from April 2018 thru November 2019 in a tertiary care pediatric emergency department (ED) and inpatient pediatric psychiatric unit enrolling acutely suicidal adolescent patients. Patients wore a wrist device that used photoplethysmography for 7 days during their acute hospitalization to measure heart rate variability (HRV). During that time, Columbia Suicide Severity Scores (CSSRS) were assessed at 3 time points.

RESULTS

There was complete device data and follow-up for 51 patients. There was an increase in the high frequency (HF) component of HRV in patients that had a 25% or greater decrease in their CSSRS (mean difference 11.89 ms/ Hz ; p-value 0.005). Patients with a CSSRS≥15 on day of enrollment had a lower, although not statistically significant, HF component (mean difference -8.34 ms/ Hz; p-value 0.071).

CONCLUSION

We found an inverse correlation between parasympathetic activity measured through the HF component and suicidality in an acutely suicidal population of adolescents. Wearable technology may have the ability to improve outpatient monitoring for earlier detection and intervention.

Heart Rate Complexity in US Army Forward Surgical Teams During Pre Deployment Training

INTRODUCTION

For trauma triage, the US Army has developed a portable heart rate complexity (HRC) monitor, which estimates cardiac autonomic input and the activity of the hypothalamic-pituitary-adrenal (HPA) axis. We hypothesize that autonomic/HPA stress associated with predeployment training in U.S. Army Forward Surgical Teams will cause changes in HRC.

MATERIALS AND METHODS

A prospective observational study was conducted in 80 soldiers and 10 civilians at the U.S. Army Trauma Training Detachment. Heart rate (HR, b/min), cardiac output (CO, L/min), HR variability (HRV, ms), and HRC (Sample Entropy, unitless), were measured using a portable non-invasive hemodynamic monitor during postural changes, a mass casualty (MASCAL) situational training exercise (STX) using live tissue, a mock trauma (MT) STX using moulaged humans, and/or physical exercise.

RESULTS

Baseline HR, CO, HRV, and HRC averaged 72 ± 11b/min, 5.6 ± 1.2 L/min, 48 ± 24 ms, and 1.9 ± 0.5 (unitless), respectively. Supine to sitting to standing caused minimal changes. Before the MASCAL or MT, HR and CO both increased to ~125% baseline, whereas HRV and HRC both decreased to ~75% baseline. Those values all changed an additional ~5% during the MASCAL, but an additional 10 to 30% during the MT. With physical exercise, HR and CO increased to >200% baseline, while HRV and HRC both decreased to 40 to 60% baseline; these changes were comparable to those caused by the MT. All the changes were P < 0.05.

CONCLUSIONS

Various forms of HPA stress during Forward Surgical Team STXs can be objectively quantitated continuously in real time with a portable non-invasive monitor. Differences from resting baseline indicate stress anticipating an impending STX whereas differences between average and peak responses indicate the relative stress between STXs. Monitoring HRC could prove useful to field commanders to rapidly and objectively assess the readiness status of troops during STXs or repeated operational missions. In the future, health care systems and regulatory bodies will likely be held accountable for stress in their trainees and/or obliged to develop wellness options and standardize efforts to ameliorate burnout, so HRC metrics might have a role, as well.

Prevalence, course, and determinants of suicide ideation and attempts in patients with a depressive and/or anxiety disorder: A review of NESDA findings

BACKGROUND

Depressive and anxiety disorders are often associated with suicide ideation (SI) and attempt (SA). However, analyses of prevalence, course, and more specific risk mechanisms are needed to improve knowledge and detection of high risk individuals with depressive and anxiety disorders. Previous studies often lacked statistical power, assessment of detailed determinants and follow-up measurements.

METHODS

The Netherlands Study of Depression and Anxiety (NESDA), a large cohort study, overcomes some earlier limitations. Scale for Suicide Ideation and Compositive Interview Diagnostic Instrument data were analyzed to report on prevalence of SI and SA. Additionally, important sociodemographic, clinical, psychological, environmental, and neurobiological determinants and course of SI and SA identified in depressive and/or anxiety disorder respondents in 16 NESDA articles were summarized.

RESULTS

Within respondents with 12-month diagnosis (n=1,783), SI and 12-month SA prevalence ranged from 17.1-20.1% and 0.8-3.0% respectively across 5 waves during 9-year follow-up and SI was highly recurrent. Both SI and SA were especially associated with comorbid depression and anxiety, higher clinical severity, sleep dysfunctions, higher aggression and hopelessness, and childhood trauma. In the (neuro)biological domain, SI was linked with immune dysregulation and SA with abnormal brain activity during emotion processing and genetic risk.

LIMITATIONS

Most articles were cross-sectional in nature, preventing causal inferences and no conclusions could be drawn about the overall magnitude of results.

CONCLUSION

SI and SA are multifactorial phenomena and especially prevalent amongst comorbid depressive and anxiety respondents. Considering many overlapping SI and SA determinants, more neurobiological determinants and use of innovative methodological techniques are desirable.

Association of Resting Heart Rate and Heart Rate Variability With Proximal Suicidal Risk in Patients With Diverse Psychiatric Diagnoses

Objectively measurable biomarkers have not been applied for suicide risk prediction. Resting heart rate (HR) and heart rate variability (HRV) showed potential as trans-diagnostic markers associated with suicide. This study aimed to investigate the associations of resting HR and HRV on proximal suicide risk in patients with diverse psychiatric diagnoses. This chart review study used the medical records of psychiatric patients who visited the outpatient clinic at an academic tertiary hospital. A total of 1,461 patients with diverse psychiatric diagnoses was included in the analysis. Proximal suicide risk was measured using the Mini-International Neuropsychiatric Interview (MINI) suicidal score. Linear regression analyses with the MINI suicidal score as a dependent variable and binary logistic regression analyses with moderate-to-high suicide risk (MINI suicidal risk score ≥6) as a dependent variable were conducted to explore the effects of resting HR and HRV parameters on acute suicide risk after adjusting for age, sex, presence of major depressive disorder (MDD) and bipolar disorder (BD), severity of depression and anxiety severity. We found that 55 (34.6%) patients in the MDD group, 40 (41.7%) in the BD group and 36 (3.9%) in the others group reported moderate-to-high suicide risk. Linear regression analysis revealed that both resting HR and root-mean-square of successive difference (RMSSD) had significant associations with the MINI suicidal score (P = 0.037 with HR, P = 0.003 with RMSSD). In logistic regression, only RMSSD showed a significant association with moderate-to-high suicide risk (P = 0.098 with HR, P = 0.019 with RMSSD), which remained significant in subgroup analysis with patients who reported any suicide-related symptom (MINI suicidal score >0; n = 472; P = 0.017 with HR, P = 0.012 with RMSSD). Our study findings suggest the potential for resting HR and RMSSD as biomarkers for proximal suicide risk prediction. Further research with longitudinal evaluation is needed to confirm our study findings.

Heart Rate Variability Duration: Expanding the Ability of Wearable Technology to Improve Outpatient Monitoring?

Heart rate variability (HRV) evaluates beat-to-beat interval (BBI) differences and is a suggested marker of the autonomic nervous system with diagnostic/monitoring capabilities in mental health; especially parasympathetic measures. The standard duration for short-term HRV analysis ranges from 24 h down to 5-min. However, wearable technology, mainly wrist devices, have large amounts of motion at times resulting in need for shorter duration of monitoring. The objective of this study was to evaluate the correlation between 1 and 5 min segments of continuous HRV data collected simultaneously on the same patient. Subjects wore a patch electrocardiograph (Cardea Solo, Inc.) over a 1-7 day period. For every consecutive hour the patch was worn, we selected a 5-min, artifact-free electrocardiogram segment. HRV metric calculation was performed to the entire 5-min segment and the first 1-min from this same 5-min segment. There were 492 h of electrocardiogram data collected allowing calculation of 492 5 min and 1 min segments. 1 min segments of data showed good correlation to 5 min segments in both time and frequency domains: root mean square of successive difference (RMSSD) (R = 0.92), high frequency component (HF) (R = 0.90), low frequency component (LF) (R = 0.71), and standard deviation of NN intervals (SDNN) (R = 0.63). Mental health research focused on parasympathetic HRV metrics, HF and RMSSD, may be accomplished through smaller time windows of recording, making wearable technology possible for monitoring.

ADAPTED TO FEAR: FEARLESSNESS ABOUT DEATH IS ASSOCIATED WITH HEART RATE VARIABILITY

Objective: Capability for suicide, which refers to an individual's ability to enact potentially lethal harm to oneself and overcome the fear of dying, is an empirically supported component of the Interpersonal-Psychological Theory of Suicide. Although an abundance of research has examined capability for suicide through the use of self-report data, little research has assessed specific psychophysiological mechanisms that may contribute to capability for suicide. We assessed relationships between capability for suicide (fearlessness about death and pain tolerance), high frequency heart rate variability (HF HRV), and subjectively reported fear during a death related event. Given that greater HRV is associated with calmness and lack of distress, we predicted that HRV during a fearful event would be positively associated with the capability for suicide.

Method: Data were collected from 101 undergraduates. Participants self-reported fearlessness about death and had their pain tolerance assessed with an algometer. HF HRV was assessed prior to, during, and following a film-viewing task designed to elicit fear of death.

Results: Correlations revealed that fearlessness about death was negatively associated with self-reported fear during the film viewing and positively associated with self-reported and objective pain tolerance. Linear regressions found that fearlessness about death, but not self-reported or objective pain tolerance, was positively associated with HF HRV during the film-viewing and recovery.

Discussion: During a fearful, death related event, greater HF HRV was associated with greater fearlessness about death, suggesting that HF HRV may represent one possible mechanism through which fearlessness about death is maintained.

Objective measurement of sleep, heart rate, heart rate variability, and physical activity in suicidality: A systematic review

BACKGROUND

Emerging literature suggests that the arousal and regulatory systems as measured by sleep-wakefulness, heart rate (HR) and heart rate variability (HRV) may be powerful objective warning signs of suicidality. However, there is no systematic literature review examining the association between objective measurements of these variables with suicide and suicidal behavior.

METHODS

A web-based, systematic literature search using PubMed and EMBASE was conducted for articles that measured sleep-wakefulness and HR/HRV quantitatively in association with suicide. Search results were limited to human subjects and articles published in peer-reviewed journals in English. There were no restrictions for age, sex, settings and durations of measurements, types of mental illnesses, or comorbidity.

RESULTS

Twenty-three studies were included in the current systematic review. Across the studies, consistent patterns of disturbed sleep-wakefulness such as greater sleep onset latency and lower sleep efficiency were related to suicide. In addition, higher HR and lower variance of R-R intervals was an indicator of risk of suicide.

LIMITATIONS

Studies that used different equipment for sleep studies (i.e., polysomnography, electroencephalogram, actigraphy) were combined, and potential differences in their findings due to the different equipment were not considered.

CONCLUSIONS

Findings provide initial evidence for consistent patterns of sleep-wakefulness and HR/HRV possibly associated with suicidality; however, more studies are needed in order to identify the precise objective variables (e.g., sleep onset latency, high-frequency HRV), as well as time-varying patterns in these variables, that are related to acute suicide risk.

Blunted Arousal in Response to Psychological Stress is Associated with Current Suicide Ideation

The purpose of this study was to test the association between arousal in response to psychological stress, as measured by standardized maximum decrease in high-frequency heart rate variability (HF HRV) during a stressful laboratory task, and current suicide ideation (SI). 81 emerging adult college students completed a stressful laboratory task consisting of the computerized Stroop and Cyberball while having their heart activity recorded. Spectral analysis and Fast Fourier transformations were used to decompose and transform the recording into the high (0.15 Hz-0.4 Hz) frequency component. After the task, participants completed the Beck Scale for Suicide Ideation to measure current SI, the Beck Depression Inventory-II to assess depressive symptom severity, and a brief medical history. Multivariate negative binomial regression analysis showed that the negative association between SI and arousal in response to psychological stress remained statistically significant when suicide attempt history, depressive symptom severity, female gender, and current smoking behavior were controlled. Identification of potential biomarkers for SI is important for suicide behavior prevention given limits to self-report SI assessment. Our results suggest arousal in response to psychological stress merits further consideration as a biomarker for current SI.

Candidate Biomarkers of Suicide Crisis Syndrome: What to Test Next? A Concept Paper

BACKGROUND

There has been increasing interest in both suicide-specific diagnoses within the psychiatric nomenclature and related biomarkers. Because the Suicide Crisis Syndrome-an emotional crescendo of several interrelated symptoms-seems to be promising for the identification of individuals at risk of suicide, the aim of the present paper is to review the putative biological underpinnings of the Suicide Crisis Syndrome symptoms (entrapment, affective disturbance, loss of cognitive control, hyperarousal, social withdrawal).

METHODS

A PubMed literature search was performed to identify studies reporting a link between each of the 5 Suicide Crisis Syndrome symptoms and biomarkers previously reported to be associated with suicidal outcomes.

RESULTS

Disturbances in the hypothalamic-pituitary-adrenal axis, with dysregulated corticotropin-releasing hormone and cortisol levels, may be linked to a sense of entrapment. Affective disturbance is likely mediated by alterations in dopaminergic circuits involved in reward and antireward systems as well as endogenous opioids. Loss of cognitive control is linked to altered neurocognitive function in the areas of executive function, attention, and decision-making. Hyperarousal is linked to autonomic dysregulation, which may be characterized by a reduction in both heart rate variability and electrodermal activity. Social withdrawal has been associated with oxytocin availability. There is also evidence that inflammatory processes may contribute to individual Suicide Crisis Syndrome symptoms.

CONCLUSION

The Suicide Crisis Syndrome is a complex syndrome that is likely the consequence of distinct changes in interconnected neural, neuroendocrine, and autonomic systems. Available clinical and research data allow for development of empirically testable hypotheses and experimental paradigms to scrutinize the biological substrates of the Suicide Crisis Syndrome.

Toward clinical digital phenotyping: a timely opportunity to consider purpose, quality, and safety

The use of data generated passively by personal electronic devices, such as smartphones, to measure human function in health and disease has generated significant research interest. Particularly in psychiatry, objective, continuous quantitation using patients' own devices may result in clinically useful markers that can be used to refine diagnostic processes, tailor treatment choices, improve condition monitoring for actionable outcomes, such as early signs of relapse, and develop new intervention models. If a principal goal for digital phenotyping is clinical improvement, research needs to attend now to factors that will help or hinder future clinical adoption. We identify four opportunities for research directed toward this goal: exploring intermediate outcomes and underlying disease mechanisms; focusing on purposes that are likely to be used in clinical practice; anticipating quality and safety barriers to adoption; and exploring the potential for digital personalized medicine arising from the integration of digital phenotyping and digital interventions. Clinical relevance also means explicitly addressing consumer needs, preferences, and acceptability as the ultimate users of digital phenotyping interventions. There is a risk that, without such considerations, the potential benefits of digital phenotyping are delayed or not realized because approaches that are feasible for application in healthcare, and the evidence required to support clinical commissioning, are not developed. Practical steps to accelerate this research agenda include the further development of digital phenotyping technology platforms focusing on scalability and equity, establishing shared data repositories and common data standards, and fostering multidisciplinary collaborations between clinical stakeholders (including patients), computer scientists, and researchers.

Novel Treatment Targets Based on Insights in the Etiology of Depression: Role of IL-6 Trans-Signaling and Stress-Induced Elevation of Glutamate and ATP

Inflammation and psychological stress are risk factors for major depression and suicide. Both increase central glutamate levels and activate the hypothalamic-pituitary-adrenal axis and the sympathetic nervous system. Both factors also affect the function of the chloride transporters, Na-K-Cl-cotransporter-1 (NKCC1) and K-Cl-cotransporter-2 (KCC2), and provoke interleukin-6 (IL-6) trans-signaling. This leads to measurable increases in circulating corticosteroids, catecholamines, anxiety, somatic and psychological symptoms, and a decline in cognitive functions. Recognition of the sequence of pathological events allows the prediction of novel targets for therapeutic intervention. Amongst others, these include blockade of the big-K potassium channel, blockade of the P2X4 channel, TYK2-kinase inhibition, noradrenaline α2B-receptor antagonism, nicotinic α7-receptor stimulation, and the Sgp130Fc antibody. A better understanding of downstream processes evoked by inflammation and stress also allows suggestions for tentatively better biomarkers (e.g., SERPINA3N, MARCKS, or ¹³C-tryptophan metabolism).

Development and validation of an emotional picture set of self-injury (EPSI) for borderline personality disorder: protocol for a validation study

INTRODUCTION

Borderline personality disorder (BPD) is a severe psychiatric disorder that is characterised by major problems in emotion regulation. Affected persons frequently engage in non-suicidal self-injury (NSSI) to regulate emotions. NSSI is associated with high emotionality in patients with BPD and it can be expected that stimuli depicting scenes of NSSI elicit an emotional response indicative of BPD. The present study protocol describes the development and validation of an emotional picture set of self-injury (EPSI) to advance future research on emotion regulation in BPD.

METHODS AND ANALYSIS

The present validation study aims to develop and validate an emotional picture set relevant for BPD. Emotional responses to EPSI as well as to a neutral picture set will be investigated in a sample of 30 patients with BPD compared with 30 matched, healthy controls and to 30 matched depressive controls. Emotional responses will be assessed by heart rate variability, facial expression and Self-Assessment Manikin.

ETHICS AND DISSEMINATION

Ethics approval was obtained by the medical ethics committee of the Carl-von-Ossietzky University of Oldenburg, Germany (registration: 2017-044). The results of the trial will be submitted for publication in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

NCT03149926; Pre-results.

Autonomic correlates of lifetime suicidal thoughts and behaviors among adolescents with a history of depression

Suicidal thoughts and behaviors (STBs) have been associated with emotion dysregulation and atypical responses to affective and stressful stimuli. To investigate the psychophysiology involved, we measured changes in respiratory sinus arrhythmia (RSA) and cardiac pre-ejection period (PEP; indexing parasympathetic and sympathetic functioning, respectively) in response to stressful- and sadness-eliciting laboratory probes. Our sample included adolescents with a history of depression and STBs (n = 177), adolescents with a history of depression but no history of STBs (n = 47), and healthy controls (n = 175). The outcome of interest was the most severe form of clinician-rated STBs across the subject's lifetime. In partial support of our hypotheses, during the stressful task, adolescents with a history of depression and STBs did not evidence the RSA decrease that was exhibited by controls and displayed greater PEP shortening compared to ever-depressed adolescents with no lifetime STBs. No group differences were found in either RSA or PEP reactivity to the sadness-eliciting stimulus. As expected, severity of STBs was positively correlated with the extent of PEP shortening during the stressful task. The results suggest that adolescents with a history of depression and STBs experience blunted parasympathetic responses to stress along with compensatory efforts. Our findings contribute to a better understanding of STBs among youths and underscore that future studies should examine physiological risk factors for these psychopathological outcomes.

Childhood Maltreatment, Self-esteem, and Suicidal Ideation in a Low-SES Emerging Adult Sample: The Moderating Role of Heart Rate Variability

Childhood maltreatment is associated with risk for suicidal ideation later in life, yet more research is needed on the indirect effects and bioregulatory protective factors in this association. The present study aimed to investigate the indirect influence of childhood maltreatment on suicidal ideation in emerging adulthood via level of self-esteem, and examine the moderating role of heart rate variability (HRV; a proxy for emotion regulation) in this indirect association. The study included a sample of 167 non-metropolitan emerging adults (M_age = 21.17, 55.8% female) of low-socioeconomic status (low-SES). HRV data were obained using an electrocardigram, whereas childhood maltreatment, suicidal ideation, and self-esteem data were obtained via self-report. Childhood maltreatment was indirectly associated with suicidal ideation via reduced self-esteem. HRV buffered this indirect association. Childhood maltreatment poses a risk for the development of suicidal ideation. Interventions that bolster self-esteem and emotion regulation may reduce suicide risk for emerging adults with a history of childhood maltreatment.

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.

Toward subtyping of suicidality: Brief suicidal ideation is associated with greater stress response

BACKGROUND

Suicide is a heterogeneous phenomenon, and thus defining more homogeneous subgroups may help in understanding its underlying biology and ultimately in its prevention. Suicidal ideation is far more common than suicidal behavior and predicts future suicide attempts. Hypothalamic-pituitary-adrenal (HPA)-axis reactivity has been implicated in individuals with suicidal ideation but findings are mixed with some studies showing increased and others demonstrating decreased reactivity. This suggests that dysregulation of HPA-axis is related to a specific character of suicidal ideation. We hypothesized that individuals with brief suicidal ideation are more stress responsive than those with longer/continuous ideation.

METHODS

Thirty-five individuals with major depressive disorder (MDD) and 23 healthy volunteers (HVs), aged 18-65 years, underwent the Trier Social Stress Test (TSST). Salivary cortisol was measured at 6 time-points before and during TSST. Total severity and duration of current suicidal ideation were assessed using the Beck Scale for Suicidal Ideation (SSI). Brief suicidal ideators (N = 18), longer/continuous ideators (N = 17) and HVs were compared regarding cortisol response, baseline cortisol and total output.

RESULTS

Participants with brief suicidal ideation had greater cortisol response compared to those with longer/continuous ideation and HVs, even after controlling for relevant covariates. However, total SSI score was not associated with cortisol response. Baseline cortisol and total output were not related to overall severity or duration of suicidal ideation.

LIMITATIONS

The cross-sectional design and modest sample limit generalizability of the results.

CONCLUSIONS

Hyper-responsiveness of HPA-axis to social stress is associated with brief suicidal ideation, possibly defining a pathway for exploring the biological subtyping of suicidal individuals.

Associations between symptoms of depression and heart rate variability: An exploratory study

Major depressive disorder (MDD) is associated with decreased heart rate variability (HRV), a predictor of cardiovascular morbidity by many, but not all studies. This inconsistency could be due to the association of HRV with specific depressive symptoms. Here, we investigated the association of HRV parameters with components of depressive symptoms from 120 MDD patients, at baseline of a published trial comparing the effect of sertraline to transcranial direct current stimulation. We used Principal Component Analysis to extract components of the Hamilton Rating Scale for Depression (HAM-D-17), the Montgomery Asberg Depression Rating Scale (MADRS) and the Beck Inventory for Depressive Symptomatology (BDI). We constructed one equation of multiple linear regression for each HRV parameter as the dependent variable, and the components of depressive symptoms of the three scales as the independent ones, adjusted for age and gender. A component of HAM-D-17 predicted LF/HF (low frequency/high frequency) and a component of MADRS predicted LF (low frequency). "Guilt" and "loss of interest/pleasure in activities" were present in the components of both scales, and the MADRS component also included "psychomotor retardation". These results suggest that melancholic features might be relevant for the association between MDD and HRV. Considering multiple comparisons, these results are preliminary.

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.

Disrupted physiological reactivity among children with a history of suicidal ideation: Moderation by parental expressed emotion-criticism

OBJECTIVE

The goal of this study was to examine physiological reactivity during parent-child interactions in children with and without a history of suicidal ideation (SI), a group known to be at increased risk for suicidal thoughts and behaviors in the future. We also examined the potential moderating role of parental expressed emotion-criticism (EE-Crit) to determine whether the presence of parental criticism may help to identify a subgroup of children with a history of SI most at risk for physiological dysregulation.

METHOD

Participants were 396 children (age 7-11; 54% male, 71.7% Caucasian) and their biological parent. Children's levels of high frequency heart rate variability (HF-HRV) were assessed during a resting baseline period followed by a positive and negative discussion with their parent. Additionally, parents completed the Five-Minute Speech Sample to determine levels of EE-Crit toward their child, and children completed an interview assessing their history of SI.

RESULTS

Consistent with our hypothesis, we found that exposure to parental criticism moderated the relation between a child's history of SI and their HF-HRV reactivity to the discussions. Specifically, while most children exhibited the typical pattern of HF-HRV suppression from baseline to both interactions, the highest risk children (i.e., children with a history of SI who also had highly critical parents) did not display any change in HF-HRV across the tasks, suggesting a failure to engage a typical psychophysiological response during emotional contexts.

CONCLUSIONS

These results suggest a specific physiological mechanism that may place these children at risk for suicidal thoughts and behaviors in the future.

Resting respiratory sinus arrhythmia in suicide attempters

Although suicide attempts (SA) occur across a broad range of diagnoses as well as in the absence of a diagnosable disorder, most studies to date have focused on them within a single, specific disorder. Consistent with the NIMH RDoC initiative to identify biobehavioral vulnerabilities that cut across diagnoses, the goal of the present study was to examine potential differences in resting respiratory sinus arrhythmia (RSA) levels in a large, diagnostically heterogeneous sample of women with and without a history of SA who were matched on a broad range of demographic and clinical variables. Participants were 112 women with (n = 56) and without (n = 56) a history of SA recruited from the community. The two groups were equated on approximate age, race, household income, and lifetime histories of psychiatric diagnoses. Resting electrocardiogram was recorded during a 2-min rest period. RSA was calculated via spectral power analyses with a fast Fourier transform. We found that women with a history of SA exhibited significantly lower resting RSA levels than women with no history of SA, and this difference was maintained even after statistically controlling for the potential influence of women's history of psychiatric diagnoses and their current symptoms of depression and anxiety. These findings suggest the presence of a link between resting RSA and SA history.

Nonverbal behaviors are associated with increased vagal activity in major depressive disorder: Implications for the polyvagal theory

BACKGROUND

Major depressive disorder (MDD) is associated with impairments in nonverbal behaviors (NVBs) and vagal activity. The polyvagal theory proposes that vagal activity regulates heart rate and NVBs by modulating a common anatomically and neurophysiologically discrete social engagement system. However, the association between these putative endophenotypes has not yet been explored. We hypothesize that in MDD, NVBs indicating positive affects and social interest and those indicating negative feelings and social disinterest could be associated with different patterns of vagal activity.

METHODS

For this cross-sectional study we recruited 50 antidepressant-free participants with moderate-to-severe MDD. Vagal activity was indexed by heart rate variability (HRV) measures, and positive and negative nonverbal behaviors (NVBs) by a validated ethogram. Associations between NVBs and HRV were explored by bivariate analyses and multivariable models were adjusted by age, gender, depression severity, and self-reported positive and negative affects.

RESULTS

HRV measures indicative of higher vagal activity were positively correlated with positive NVBs exhibited during the clinical interview. Conversely, NVBs related to negative affects, low energy and social disinterest were not associated with HRV.

LIMITATIONS

Absence of a control group.

CONCLUSIONS

The findings highlight that the examined depression endophenotypes (nonverbal behaviors and vagal activity) are related, shedding light on MDD pathophysiology in the context of the polyvagal theory.