Increased fear-potentiated startle in major depressive disorder patients with lifetime history of suicide attempt

Toward objective characterizations of suicide risk: A narrative review of laboratory-based cognitive and behavioral tasks

Although suicide is a leading cause of preventable death worldwide, current prevention efforts have failed to substantively mitigate suicide risk. Suicide research has traditionally relied on subjective reports that may not accurately differentiate those at high versus minimal risk. This narrative review supports the inclusion of objective task-based measures in suicide research to complement existing subjective batteries. The article: 1) outlines risk factors proposed by contemporary theories of suicide and highlights recent empirical findings supporting these theories; 2) discusses ongoing challenges associated with current risk assessment tools and their ability to accurately evaluate risk factors; and 3) analyzes objective laboratory measures that can be implemented alongside traditional measures to enhance the precision of risk assessment. To illustrate the potential of these methods to improve our understanding of suicide risk, the article reviews how acute stress responses in a laboratory setting can be modeled, given that stress is a major precipitant for suicidal behavior. More precise risk assessment strategies can emerge if objective measures are implemented in conjunction with traditional subjective measures.

History of suicide attempt associated with amygdala and hippocampus changes among individuals with schizophrenia

Abnormalities in subcortical brain structures may reflect higher suicide risk in mood disorders, but less is known about its associations for schizophrenia. This cross-sectional imaging study aimed to explore whether the history of suicide attempts was associated with subcortical changes among individuals with schizophrenia. We recruited 44 individuals with schizophrenia and a history of suicide attempts (SZ-SA) and 44 individuals with schizophrenia but without a history of suicide attempts (SZ-NSA) and 44 healthy controls. Linear regression showed that SZ-SA had smaller volumes of the hippocampus (Cohen's d = -0.72), the amygdala (Cohen's d = -0.69), and some nuclei of the amygdala (Cohen's d, -0.57 to -0.72) than SZ-NSA after adjusting for age, sex, illness phase, and intracranial volume. There was no difference in the volume of the subfields of the hippocampus. It suggests the history of suicide attempts is associated with subcortical volume alterations in schizophrenia.

Magnetoencephalography biomarkers of suicide attempt history and antidepressant response to ketamine in treatment-resistant major depression

BACKGROUND

This study examined magnetoencephalographic (MEG) correlates of suicidal ideation (SI) and suicide attempt history in patients with treatment-resistant major depression (TRD) at baseline and following subanesthetic-dose ketamine infusion.

METHODS

Twenty-nine drug-free TRD patients (12 suicide attempters/17 non-attempters) participated in a crossover randomized trial of ketamine. MEG data were collected during an attentional dot probe task with emotional face stimuli at baseline and several hours post-ketamine infusion. Synthetic aperture magnetometry was used to project source power in the theta, alpha, beta, and gamma frequencies for angry-neutral, happy-neutral, and neutral-neutral face pairings during a one-second peristimulus period. Mixed models were used to test for clinical, behavioral, and electrophysiological effects of group, emotion, session, and SI score.

RESULTS

Ketamine significantly reduced SI and depression across the sample. Post-ketamine, attempters had improved accuracy and non-attempters had reduced accuracy on the task. SI was positively associated with gamma power in regions of the frontal and parietal cortices across groups. In an extended amygdala-hippocampal region, attempters differed significantly in their emotional reactivity to angry versus happy faces as indexed by theta power differences, irrespective of drug. Ketamine significantly reduced the association between alpha power and SI for angry compared with happy faces in a fronto-insular/anterior cingulate region important for regulating sensory attentiveness.

LIMITATIONS

Limitations include a small sample size of attempters.

CONCLUSIONS

The findings highlight key differences in band-limited power between attempters and non-attempters and reinforce previous findings that ketamine has distinct response properties in patients with a suicide history.

The Dynamic Relationship Between Alpha and Beta Power and Next-Day Suicidal Ideation in Individuals With Treatment-Resistant Depression

Background

Nocturnal wakefulness has emerged as a potential predictor of short-term suicide risk. This analysis used dynamic temporal patterns in alpha and beta power and global sleep metrics to explore the possible link between next-day suicidal ideation (NDSI) and wakefulness measures in unmedicated participants with treatment-resistant depression.

Methods

Thirty-three medication-free participants with treatment-resistant depression completed overnight polysomnography. Alpha and beta spectral power as functions over time were used to represent arousal-related components of the dynamic sleep process. A functional data analytic approach (multilevel functional principal component analysis [MFPCA]) was used to preserve the oscillatory nature of the data; MFPCA PC scores were then associated with NDSI. Associations between NDSI and polysomnography-defined wakefulness after sleep onset, sleep efficiency, and total sleep time were also evaluated.

Results

NDSI had the strongest relationship with the second beta PC score (slope = 0.09 [90% credible interval, 0.03 to 0.14]), which represented an oscillating pattern that reflected disturbed sleep. The first PCs from both alpha and beta MFPCAs represented the overall magnitude of power and were most closely associated with traditional polysomnography metrics but were not related to NDSI. Results were equivocal for wakefulness after sleep onset with NDSI and did not support a relationship between NDSI and either sleep efficiency or total sleep time, highlighting the value of information contained in oscillating electroencephalogram patterns for identifying physiological links between nocturnal wakefulness and NDSI.

Conclusions

This study leveraged the dynamic nature of wakefulness-related electroencephalogram frequencies and provides a potential electrophysiological link between suicidal ideation and wakefulness during sleep in individuals with treatment-resistant depression.

The novel vasopressin receptor (V1aR) antagonist SRX246 reduces anxiety in an experimental model in humans: a randomized proof-of-concept study

RATIONALE

Arginine vasopressin (AVP) is a neuropeptide that modulates both physiological and emotional responses to threat. Until recently, drugs that target vasopressin receptors (V1a) in the human central nervous system were unavailable. The development of a novel V1a receptor antagonist, SRX246, permits the experimental validation of vasopressin's role in the regulation of anxiety and fear in humans.

OBJECTIVES

Here, we examined the effects of SRX246 in a proof-of-concept translational paradigm of fear (phasic response to imminent threat) and anxiety (prolonged response to potential threat).

METHODS

Healthy volunteers received both SRX246 and placebo in a randomized, double-blind, counter-balanced order separated by a 5-7-day wash-out period. Threat consisted of unpleasant electric shocks. The "NPU" threat test probed startle reactivity during predictable threat (i.e., fear-potentiated startle) and unpredictable threat (i.e., anxiety-potentiated startle).

RESULTS

As predicted, SRX246 decreased anxiety-potentiated startle independent of fear-potentiated startle.

CONCLUSIONS

As anxiety-potentiated startle is elevated in anxiety and trauma-associated disorders and decreased by traditional anxiolytics such as SSRIs and benzodiazepines, the V1a receptor is a promising novel treatment target.

Distinguishing veterans with suicidal ideation from suicide attempt history: The role of emotion reactivity

INTRODUCTION

Growing evidence suggests emotion reactivity-sensitivity and intensity of emotional experience-may represent a diathesis for suicide risk. However, our understanding of its ability to differentiate risk for suicidal ideation (SI) from suicide attempt (SA) is limited.

METHOD

This study compares Veterans with SI (n = 81) to Veterans with SA (n = 177) history on factors relevant to emotion reactivity to determine which variable(s) best differentiate groups. Variables examined are multimodal: (a) self-report: childhood trauma, combat exposure; (b) clinician-assessed: non-suicidal self-injury (NSSI), structured diagnostic interview of psychopathology; and (c) psychophysiological: affect-modulated startle (AMS; proxy for amygdala reactivity and emotion reactivity) to unpleasant pictures was examined in a subset (n = 90).

RESULTS

SA history was independently predicted by NSSI history, MDD, PTSD, and SUD diagnosis. Childhood trauma and combat exposure did not differentiate groups. The composite risk index demonstrated good accuracy (AUC=0.71, sensitivity=0.90, specificity=0.49). Only AMS independently predicted SA history when added to the model and accuracy was improved (AUC=0.82, sensitivity=0.85, specificity=0.56).

CONCLUSION

NSSI history, MDD, PTSD, and SUD diagnosis may be salient risk factors for this population. However, emotion reactivity is a more parsimonious predictor of SA history among Veterans suggesting it is an important treatment target among Veterans with SI.

The relationship between suicide-specific rumination and suicidal intent above and beyond suicidal ideation and other suicide risk factors: A multilevel modeling approach

Suicide-specific rumination, characterized by perseveration on and difficulties disengaging from suicidal thoughts and ideas, has been linked to increased suicide risk; however, previous studies were limited by the use of a cross-sectional design and relatively lower risk samples. This study aimed to replicate and extend previous findings by examining the short-term longitudinal association between suicide-specific rumination and suicidal intent, controlling for numerous robust covariates, in a sample of community-based adults at high risk for suicide, who were recruited from suicide-related forums online. Ninety-one adults with significant suicidal ideation (M_age = 27.03, SD = 8.64; 53.8% female, 44.0% male, 1.1% non-binary, 1.1% transgender female) completed brief online self-report measures at six time-points, each three days apart. Multilevel modeling analyses indicated that suicide-specific rumination was associated with suicidal intent, above and beyond suicidal ideation, perceived burdensomeness, thwarted belongingness, agitation, insomnia, nightmares, and sociodemographic characteristics. Further, a lagged model demonstrated that suicide-specific rumination predicted subsequent time-point suicidal intent, controlling for current suicidal intent and all other covariates. Overall, these findings suggest that perseverating on one's suicidal thoughts may serve as a proximal factor that increases suicide risk. Future investigations should explore potential mechanisms of this association, as well as interventions that may reduce suicide-specific rumination.

The neural correlates of low social integration as a risk factor for suicide

Low social integration is commonly described in acutely suicidal individuals. Neural mechanisms underlying low social integration are poorly understood in depressed and suicidal patients. We sought to characterize the neural response to low social integration in acutely suicidal patients. Adult depressed patients within 3 days of a suicide attempt (n = 10), depressed patients with suicidal ideation (n = 9), non-suicidal depressed patients (n = 15), and healthy controls (N = 18) were administered the Cyberball Game while undergoing functional magnetic resonance imaging. We used complementary functional connectivity and region of interest data analysis approaches. There were no group differences in functional connectivity within neural network involving the pain matrix, nor in insula neural activity or the insula during either social inclusion. Superior anterior insula activity exhibited an inverted U-shaped curve across the suicide risk spectrum during social inclusion. Superior insula activity during social inclusion correlated with depression severity and psychological pain. Dorsal anterior cingulate cortex activity during social exclusion correlated with physical pain severity. Neural responses in the anterior insula significantly correlated with depression severity and with psychological pain during social inclusion, whereas dACC activity significantly correlated with physical pain during social exclusion. Recent suicidal behavior seems associated with a distinct neural response to social exclusion independently of presence of depression or suicidal thoughts.

Interactions of immediate and long-term action regulation in the course and complications of bipolar disorder

Immediate and long-term mechanisms interact in the regulation of action. We will examine neurobiology and practical clinical consequences of these interactions. Long-term regulation of immediate behavioural control is based on analogous responses to highly rewarding or stressful stimuli: (i) impulsivity is a failure of the balance between activation and inhibition in the immediate regulation of action. (ii) Sensitization is a persistently exaggerated behavioural or physiological response to highly salient stimuli, such as addictive stimuli or inescapable stress. Sensitization can generalize across classes of stimuli. (iii) Impulsivity, possibly related to poor modulation of catecholaminergic and glutamatergic functions, may facilitate development of long-term sensitized responses to stressful or addictive stimuli. In turn, impulsivity is prominent in sensitized behaviour. (iv) While impulsivity and sensitization are general components of behaviour, their interactions are prominent in the course of bipolar disorder, emphasizing roles of substance-use, recurrent course and stressors. (v) Suicide is a complex and severe behaviour that exemplifies the manner in which impulsivity facilitates behavioural sensitization and is, in turn, increased by it, leading to inherently unpredictable behaviour. (vi) Interactions between impulsivity and sensitization can provide targets for complementary preventive and treatment strategies for severe immediate and long-term behavioural disorders. Progress along these lines will be facilitated by predictors of susceptibility to behavioural sensitization. This article is part of the theme issue 'Risk taking and impulsive behaviour: fundamental discoveries, theoretical perspectives and clinical implications'.

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.

Startle during threat longitudinally predicts functional impairment independent of DSM diagnoses

Heightened responsivity to unpredictable, and perhaps predictable, threat characterizes some internalizing disorders and may be vulnerability factors for psychopathology as well. However, few studies have directly tested whether individual differences in unpredictable and/or predictable threat responding longitudinally predict symptoms of psychopathology and functional outcomes. Examining functioning is particularly important given that functioning is separable from symptoms of psychopathology. The present study examined whether electromyography startle measures of predictable and/or unpredictable threat responding was associated with interviewer-assessed symptoms of internalizing psychopathology and functional impairment at baseline (n = 409) and one-year follow-up (n = 104). Elevated startle responding to unpredictable and predictable threat longitudinally predicted a worsening of functioning over time and this effect was independent of change of symptoms over time. Importantly, threat responding at baseline predicted functional impairment during the follow-up independent of the effects of DSM-defined fear-based (e.g., panic disorder) or distress-misery (e.g., major depressive disorder) internalizing disorders. These findings provide initial support for the incremental validity of neurobiological vulnerability markers of threat responding over and above DSM disorders and highlight the importance of distinguishing functional outcomes from symptom outcomes.

Familial Aggregation and Coaggregation of Suicide Attempts and Comorbid Mental Disorders in Adults

IMPORTANCE

Clarification of the joint influence of familial patterns of suicide attempts and comorbid mental disorders can enhance the understanding and prevention of suicide attempts.

OBJECTIVE

To investigate the familial patterns of suicide attempts and comorbid mental disorders and their associations in a 2-site family study of mood and anxiety disorders.

DESIGN, SETTING, AND PARTICIPANTS

Data were obtained from 2 parallel community-based family studies conducted in the United States (National Institute of Mental Health [NIMH] study) and in Lausanne, Switzerland (PsyCoLaus study), on the comorbidity of mood and anxiety disorders. The study sample comprised 1119 adult probands and 5355 first-degree relatives. Data were collected and analyzed from October 2004 to December 2016.

MAIN OUTCOMES AND MEASURES

Lifetime suicide attempt and mental disorders in first-degree relatives, obtained through direct interviews or family history reports.

RESULTS

The study included 1119 adult probands (675 female [60.3%] and a mean [SD] age of 50 [12.0] years) and 5355 first-degree relatives (2752 female [51.4%] and a mean [SD] age of 52 [1.5] years). Of these participants, 90 (8.0%) of 1119 probands and 199 (3.7%) of 5355 relatives had a lifetime history of suicide attempt. Those with such a history had higher rates of all mental disorders, a greater number of disorders, and statistically significantly poorer current and lifetime global functioning. After adjustment for age and sex, a statistically significant association between suicide attempts in probands and in relatives was found at the NIMH site (OR, 2.6; 95% CI, 1.5-4.7), at the Lausanne site (OR, 3.1; 95% CI, 1.6-6.0), and in the combined data (OR, 2.9; 95% CI, 1.9-4.5). All mood disorder subtypes and substance use disorders were statistically significantly associated with suicide attempts. The familial association between lifetime suicide attempts in probands and relatives was not statistically significant for the combined sample (OR, 1.6; 95% CI, 1.0-2.7) after adjustment for comorbid conditions in probands and relatives. Social anxiety disorder in probands was associated with suicide attempts in relatives (OR, 2.4; 95% CI, 1.7-3.5) after controlling for comorbid mood, anxiety, and substance use disorders.

CONCLUSIONS AND RELEVANCE

Familiality of suicide attempts appears to be explained by a history of mental disorders among those with suicide attempts; the novel finding of a common familial diathesis for suicide attempts and social anxiety, particularly in combination with mood disorders, has heuristic value for future research and may be a risk marker that can inform prevention efforts.

Structural and Functional Abnormities of Amygdala and Prefrontal Cortex in Major Depressive Disorder With Suicide Attempts

Finding neural features of suicide attempts (SA) in major depressive disorder (MDD) may be helpful in preventing suicidal behavior. The ventral and medial prefrontal cortex (PFC), as well as the amygdala form a circuit implicated in emotion regulation and the pathogenesis of MDD. The aim of this study was to identify whether patients with MDD who had a history of SA show structural and functional connectivity abnormalities in the amygdala and PFC relative to MDD patients without a history of SA. We measured gray matter volume in the amygdala and PFC and amygdala-PFC functional connectivity using structural and functional magnetic resonance imaging (MRI) in 158 participants [38 MDD patients with a history of SA, 60 MDD patients without a history of SA, and 60 healthy control (HC)]. MDD patients with a history of SA had decreased gray matter volume in the right and left amygdala (F = 30.270, P = 0.000), ventral/medial/dorsal PFC (F = 15.349, P = 0.000), and diminished functional connectivity between the bilateral amygdala and ventral and medial PFC regions (F = 22.467, P = 0.000), compared with individuals who had MDD without a history of SA, and the HC group. These findings provide evidence that the amygdala and PFC may be closely related to the pathogenesis of suicidal behavior in MDD and implicate the amygdala-ventral/medial PFC circuit as a potential target for suicide intervention.

Exercise decreases defensive responses to unpredictable, but not predictable, threat

BACKGROUND

Research supports the anxiolytic effect of exercise, but the mechanism underlying this effect is unclear. This study examines the influence of exercise in healthy controls on two distinct defensive states implicated in anxiety disorders: fear, a phasic response to a predictable threat, and anxiety, a sustained response to an unpredictable threat.

METHODS

Thirty-four healthy volunteers (17 male, age M = 26.18, SD = 5.6) participated in sessions of exercise (biking at 60-70% of heart rate reserve) and control (biking at 10-20% of heart rate reserve) activity for 30 min, separated by 1 week. Threat responses were measured by eyeblink startle and assessed with the "Neutral-Predictable-Unpredictable threat test," which includes a neutral (N) and two threat conditions, one with predictable (P) and one with unpredictable (U) shock.

RESULTS

Results show that exercise versus control activity reduces startle potentiation during unpredictable threat (P = .031), but has no effect on startle potentiation during predictable threat (P = .609).

CONCLUSIONS

These results suggest that exercise reduces defensive response to unpredictable, but not predictable, threat, a dissociation that may help inform clinical indications for this behavioral intervention, as well as provide clues to its underlying neurobehavioral mechanisms.

If or when? Uncertainty's role in anxious anticipation

Uncertainty is often associated with subjective distress and a potentiated anxiety response. Occurrence uncertainty, or the inability to predict if a threat will occur, has rarely been compared experimentally with temporal uncertainty, or the inability to predict when a threat will occur. The current study aimed to (a) directly compare the anxiogenic effects of anticipating these two types of uncertain threat, as indexed by the eyeblink startle response, and (b) assess the relationship between startle response to occurrence and temporal uncertainty and individual differences in self-reported intolerance of uncertainty and anxiety. The findings indicated that anticipation during occurrence uncertainty elicited a larger startle response than anticipating a certain threat, but anticipation during temporal uncertainty was superior at potentiating startle blink overall. Additional analyses of the effects of order and habituation further highlighted temporal uncertainty's superiority in eliciting greater startle responding. This suggests that, while uncertainty is physiologically anxiety provoking, some level of certainty that the threat will occur enhances the robustness of the physiological anxiety response. However, self-reported anxiety was equivalent for temporal and occurrence uncertainty, suggesting that, while defensive responding may be more affected by temporal uncertainty, people perceive both types of uncertainty as anxiogenic. Individual differences in the intolerance of uncertainty and other anxiety measures were not related to anticipatory startle responsivity during any of the conditions.

Startling Differences: Using the Acoustic Startle Response to Study Sex Differences and Neurosteroids in Affective Disorders

PURPOSE OF REVIEW

Neuroactive steroid hormones, such as estradiol and progesterone, likely play a role in the pathophysiology of female-specific psychiatric disorders such as premenstrual dysphoric disorder (PMDD) and postpartum depression and may contribute to the marked sex differences observed in the incidence and presentation of affective disorders. However, few tools are available to study the precise contributions of these neuroactive steroids (NSs). In this review, we propose that the acoustic startle response (ASR), an objective measure of an organism's response to an emotional context or stressor, is sensitive to NSs. As such, the ASR represents a unique translational tool that may help to elucidate the contribution of NSs to sex differences in psychiatric disorders.

RECENT FINDINGS

Findings suggest that anxiety-potentiated startle (APS) and prepulse inhibition of startle (PPI) are the most robust ASR paradigms for assessing contribution of NSs to affective disorders, while affective startle response modulation (ASRM) appears less diagnostic of sex or menstrual cycle (MC) effects. However, few studies have appropriately used ASR to test a priori hypotheses about sex or MC differences. We recommend that ASR studies account for sex as a biological variable (SABV) and hormonal status to further knowledge of NS contribution to affective disorders.

Prevalence and risk factors for attempted suicide in the elderly: a cross-sectional study in Shanghai, China

BACKGROUND

Previous studies have thoroughly investigated the prevalence and risk factors for completed suicide. In marked contrast is the lack of a better understanding of attempted suicide in the elderly. The aim of this study was to estimate the prevalence of attempted suicide in the elderly and examine the associated factors.

METHODS

Using a multi-stage cluster sampling approach, a cross-sectional survey of 8,399 elderly house-dwelling residents was conducted in Shanghai, China.

RESULTS

The two-week prevalence of attempted suicide in the elderly was 0.75%. In the bivariate analysis, having no caregivers, depressive, anxiety, sad, fear, obsessive-compulsive and anger symptom, and lower scores on the Barthel Index of Activities of Daily Living and the Lawton Instrumental Activities of Daily Living Scale were significantly associated with an increased risk of attempted suicide in the elderly. In the multivariate analysis, sad and fear symptoms were significantly and independently associated with a higher risk of attempted suicide in the elderly.

CONCLUSION

The two-week prevalence of attempted suicide in the elderly is relatively high when compared with the annualized or lifetime prevalence reported in China and foreign settings. Elderly individuals with certain mental symptoms should be targeted for suicide prevention and provided with timely mental health support.

Understanding Suicide Risk within the Research Domain Criteria (RDoC) Framework: Insights, Challenges, and Future Research Considerations

Suicide is a leading cause of death worldwide. Prior research has focused primarily on sociodemographic and psychiatric risk factors with little improvement in the prediction or prevention of suicidal behavior over time. The Research Domain Criteria (RDoC) may be an especially useful framework for advancing research in this area. This paper provides a brief and broad overview of research on suicidal behavior relating to each of the RDoC domains-highlighting the RDoC construct(s) where research has focused, construct(s) where research is lacking, and suggestions for future research directions. We also discuss major challenges for suicide research within the RDoC framework, including the intersection of RDoC domains, interaction of domains with the environment, incorporation of developmental stage, integration of distal and proximal processes, and inclusion of suicide-specific constructs. We conclude by underscoring important considerations for future research aimed at using the RDoC framework to study suicidal behavior and other forms of psychopathology.

Relationships among attention networks and physiological responding to threat

Although researchers have long hypothesized a relationship between attention and anxiety, theoretical and empirical accounts of this relationship have conflicted. We attempted to resolve these conflicts by examining relationships of attentional abilities with responding to predictable and unpredictable threat - related but distinct motivational process implicated in a number of anxiety disorders. Eighty-one individuals completed a behavioral task assessing efficiency of three components of attention - alerting, orienting, and executive control (Attention Network Test - Revised). We also assessed startle responding during anticipation of both predictable, imminent threat (of mild electric shock) and unpredictable contextual threat. Faster alerting and slower disengaging from non-emotional attention cues were related to heightened responding to unpredictable threat, whereas poorer executive control of attention was related to heightened responding to predictable threat. This double dissociation helps to integrate models of attention and anxiety and may be informative for treatment development.

Functional domains as correlates of suicidality among psychiatric inpatients

BACKGROUND

Suicide remains poorly understood and unpredictable. Addressing this challenge, this study examined the independent contributions of several research domain criteria (RDoC) constructs in relation to suicidality in patients hospitalized for acute suicide risk. Specifically, we examined anhedonia, anxiety/entrapment, and attachment disturbances, reflecting disturbances in reward processes, negative valence systems, and social processes, respectively.

METHODS

Anhedonia, anxiety, entrapment, and fearful attachment, were assessed quantitatively in 135 adults hospitalized for suicidality. Current suicidality and suicidal history were assessed with the Columbia Suicide Severity Rating Scale. Bivariate analyses (with significance threshold of p<.01 to account for multiple comparisons) and multivariate models examined relationships between symptom dimensions and severity of suicidal ideation (SI). We also assessed differences between patients with a history of suicide attempt and those who exhibited only suicidal ideations.

RESULTS

Using bivariate analyses all symptoms except for fearful attachment correlated robustly with SI (r =.37-0.50, p<.001). However, when using multivariate analyses, only anhedonia (β=.28, p=.01) and entrapment (β=.19, p=.03) were independently associated with SI across the entire sample. No functional domain measures differed between patients with history of suicide attempt versus ideation only.

LIMITATIONS

The reliance on self-report data and a cross-sectional design.

CONCLUSIONS

Disturbances in reward and threat processing may represent independent factors in the development of suicidal ideation in this high suicide risk cohort. Future studies should assess their role as risk factors.

Startle amplitude during unpleasant pictures is greater in veterans with a history of multiple-suicide attempts and predicts a future suicide attempt

Recent studies demonstrate that veterans exhibit higher suicide risk compared with the general U.S.

POPULATION

A prior suicide attempt is a well-documented predictor of suicide death. Despite increased attention to clinical risk factors of suicide and efforts to develop psychosocial interventions to reduce suicide risk, the underlying biological factors that confer this risk are not well understood. This study examined affect-modulated startle (AMS) during a series of intermixed unpleasant, neutral, and pleasant pictures in a sample of 108 demographically-matched veterans at low (passive ideators: n = 26) and high risk (active ideators: n = 29; single attempters: n = 28; and multiple attempters: n = 25) for suicide based on the Columbia Suicide Severity Rating Scale. An exploratory aim involved a longitudinal component in a subset of the high-risk sample that went on to participate in a randomized 6-month clinical trial. We investigated whether baseline AMS predicts a subsequent suicide attempt at 12-month follow-up. Compared with the other three groups, multiple attempters showed greater startle potentiation during unpleasant pictures and deficient overall startle habituation from early to later trials. The groups did not differ in startle during neutral or pleasant pictures, or self-reported picture valence. Greater startle during unpleasant pictures was associated with greater emotion dysregulation as measured by the Difficulties in Emotion Regulation Scale and a future suicide attempt assessed prospectively at 12-month follow-up. These findings suggest that startle potentiation during unpleasant pictures in multiple-suicide attempters is a promising psychophysiological biomarker of suicide risk and underscore the clinical importance of targeting emotion dysregulation in the treatment of patients at-risk for suicide.

Pharmacological approaches to the challenge of treatment-resistant depression

Although monoaminergic antidepressants revolutionized the treatment of Major Depressive Disorder (MDD) over a half-century ago, approximately one third of depressed patients experience treatment-resistant depression (TRD). Such patients account for a disproportionately large burden of disease, as evidenced by increased disability, cost, human suffering, and suicide. This review addresses the definition, causes, evaluation, and treatment of unipolar TRD, as well as the major treatment strategies, including optimization, augmentation, combination, and switch therapies. Evidence for these options, as outlined in this review, is mainly focused on large-scale trials or meta-analyses. Finally, we briefly review emerging targets for antidepressant drug discovery and the novel effects of rapidly acting antidepressants, with a focus on ketamine.

Pharmacological approaches to the challenge of treatment-resistant depression

Although monoaminergic antidepressants revolutionized the treatment of Major Depressive Disorder (MDD) over a half-century ago, approximately one third of depressed patients experience treatment-resistant depression (TRD). Such patients account for a disproportionately large burden of disease, as evidenced by increased disability, cost, human suffering, and suicide. This review addresses the definition, causes, evaluation, and treatment of unipolar TRD, as well as the major treatment strategies, including optimization, augmentation, combination, and switch therapies. Evidence for these options, as outlined in this review, is mainly focused on large-scale trials or meta-analyses. Finally, we briefly review emerging targets for antidepressant drug discovery and the novel effects of rapidly acting antidepressants, with a focus on ketamine.

Improvement in suicidal ideation after ketamine infusion: relationship to reductions in depression and anxiety

OBJECTIVE

Suicide is a psychiatric emergency. Currently, there are no approved pharmacologic treatments for suicidal ideation. Ketamine is an N-methyl-D-aspartate (NMDA) receptor antagonist that rapidly reduces suicidal ideation as well as depression and anxiety, but the dynamic between these symptoms is not known. The aim of this analysis was to evaluate whether ketamine has an impact on suicidal thoughts, independent of depressive and anxiety symptoms.

METHODS

133 patients with treatment-resistant depression (major depressive disorder or bipolar I/II disorder) received a single subanesthetic infusion of ketamine (0.5 mg/kg over 40 min). Post-hoc correlations and linear mixed models evaluated the relationship between suicidal ideation and depression and anxiety symptoms using the Hamilton Depression Rating Scale (HAMD), Scale for Suicidal Ideation (SSI), Beck Depression Inventory (BDI), and Hamilton Anxiety Rating Scale (HAMA) focusing on 230 min post-infusion.

RESULTS

At 230 min post-infusion, correlations between changes in suicidal ideation and depression ranged from 0.23 to 0.44 (p < .05), accounting for up to 19% in the variance of ideation change. Correlations with anxiety ranged from 0.23 to 0.40 (p < .05), accounting for similar levels of variance. Ketamine infusion was associated with significant reductions in suicidal ideation compared to placebo, when controlling for the effects of ketamine on depression (F1,587 = 10.31, p = .001) and anxiety (F1,567 = 8.54, p = .004).

CONCLUSIONS

Improvements in suicidal ideation after ketamine infusion are related to, but not completely driven by, improvements in depression and anxiety. Investigation of the specific effects of ketamine on suicidal thoughts is warranted.