Resting-state neural mechanisms of capability for suicide and their interaction with pain - A CAN-BIND-05 Study

BACKGROUND

Suicidal ideation is highly prevalent in Major Depressive Disorder (MDD). However, the factors determining who will transition from ideation to attempt are not established. Emerging research points to suicide capability (SC), which reflects fearlessness of death and increased pain tolerance, as a construct mediating this transition. This Canadian Biomarker Integration Network in Depression study (CANBIND-5) aimed to identify the neural basis of SC and its interaction with pain as a marker of suicide attempt.

METHODS

MDD patients (n = 20) with suicide risk and healthy controls (n = 21) completed a self-report SC scale and a cold pressor task measuring pain threshold, tolerance, endurance, and intensity at threshold and tolerance. All participants underwent a resting-state brain scan and functional connectivity was examined for 4 regions: anterior insula (aIC), posterior insula (pIC), anterior mid-cingulate cortex (aMCC) and subgenual anterior cingulate cortex (sgACC).

RESULTS

In MDD, SC correlated positively with pain endurance and negatively with threshold intensity. Furthermore, SC correlated with the connectivity of aIC to the supramarginal gyrus, pIC to the paracingulate gyrus, aMCC to the paracingulate gyrus, and sgACC to the dorsolateral prefrontal cortex. These correlations were stronger in MDD compared to controls. Only threshold intensity mediated the correlation between SC and connectivity strength.

LIMITATIONS

Resting-state scans provided an indirect assessment of SC and the pain network.

CONCLUSIONS

These findings highlight point to a neural network underlying SC that is associated with pain processing. This supports the potential clinical utility of pain response measurement as a method to investigate markers of suicide risk.

The Frequency and Subjective Impact of Painful and Provocative Events on the Acquired Capability for Suicide

BACKGROUND

Leading theoretical explanations for suicide state that for suicide death to occur, a person must have sufficient capability to enact an attempt. Exposure to painful and provocative events is hypothesized to play an important role in acquiring the capability for suicide over a lifetime. Unfortunately, assessment tools for painful and provocative events have focused solely on the frequency of events, neglecting the potential contributions of perceived impact. Further, past measurements have used predetermined items for painful and provocative events thereby neglecting other relevant events. The current study uses visual analog scales (VAS) to assess both the frequency and impact of painful and provocative events and how these contribute to the capability for suicide.

METHOD

Data were collected from 787 adults via Amazon's online platform.

RESULTS

Findings indicated that the frequency VAS and impact VAS both had a moderate correlation with the original Painful and Provocative Events Scale. Greater scores on the frequency VAS were associated with increased capability, whereas lower scores on the subjective impact VAS were associated with increased capability scores. Both VAS independently predicted capability above and beyond the PPES.

LIMITATIONS

Temporal or causal associations are unable to be drawn due to cross-sectional data. In addition, the sample was largely homogenous (White = 72%, female = 63.5%), limiting generalizability.

CONCLUSIONS

These initial findings demonstrate individuals who perceive painful and provocative events as being less impactful may have increased capability, and that VAS may be appropriate to approximate the impact and frequency of painful and provocative events.

Examining the temporal stability of suicide capability among undergraduates: A latent growth analysis

BACKGROUND

Relatively few studies test the interpersonal psychological theory's monotonicity hypothesis. The monotonicity hypothesis proposes that suicide capability (i.e., fearlessness about death and pain tolerance) is stable or increases linearly with exposure to painful and provocative events. Research is conflicted, suggesting that suicide capability is static, decreases, or increases and returns to baseline. The current study thus tested this hypothesis in a sample of college students with histories of suicidal ideation. We hypothesized a stable and an increasing trajectory.

METHODS

Participants were 206 undergraduates; primarily women (73%), on average 19.05 years old, heterosexual (85%), and first-years (69%). Participants completed a baseline battery of questionnaires on suicide risk factors and daily diaries on suicide capability and suicidal ideation for 90 days (n = 7,342 surveys, 40% compliance rate). Group-based trajectory analyses were conducted with the SAS macro PROC TRAJ.

RESULTS

Modeling revealed a three group quadratic model.  Low (27.7%), Moderate (41.3%), and High (31.1%) suicide capability groups remained static over time. Baseline suicidal ideation, but not history of suicide attempts or family history of suicidal behavior, distinguished groups; participants with suicidal ideation at baseline were less likely to be in the low suicide capability group.

LIMITATIONS

Brief, dichotomized assessments, and a high attrition rate.

CONCLUSIONS

These data showed temporal stability of suicide capability and suggest that the "acquired" component of capability may be overemphasized. Clarifying the stability and modifiability of suicide capability will enable empirically-based applications of the theory to suicide prevention.

Validation of the German capability for suicide questionnaire (GCSQ) in a high-risk sample of suicidal inpatients

BACKGROUND

The German Capability for Suicide Questionnaire (GCSQ) was developed to measure fearlessness of death and pain tolerance - two constructs central to the Interpersonal Theory of Suicide. Initial scale development, definition of the factor structure and confirmation of the two-dimensional factor structure was performed in samples suffering from relatively low levels of suicide ideation/behavior. The present study aimed to validate the German Capability for Suicide Questionnaire (GCSQ) in a high-risk sample of suicidal inpatients.

METHODS

Factor structure, reliability and validity were investigated in a sample of inpatients (N = 296; 53.0% female; age in years: M = 36.81, SD = 14.27) admitted to a hospital due to a recent suicide attempt or an acute suicidal crisis (in immediate need of inpatient treatment). To establish convergent validity, interview-based assessments of lifetime suicide attempts and non-suicidal self-injury as well as questionnaire-based assessments of painful and provocative events were used. Finally, stability of GCSQ-scores over a follow-up period of 12 months was assessed.

RESULTS

Results indicated good psychometric properties, and provided additional evidence for construct validity and stability of the subscales over a one-year period, and demonstrated adequate fit of the data with respect to the original factor structure.

CONCLUSIONS

Results suggest that the GCSQ is a brief, reliable, and valid measure of capability for suicide that can be used in clinic assessment and research.

Fearlessness about death does not differ by suicide attempt method

Modern theories of suicide, such as the Interpersonal Theory of Suicide, have overcome past conceptual limitations within suicide research by examining factors that help differentiate suicide attempters from those who experience suicidal ideation, but never attempt suicide. One such factor that has been studied extensively is fearlessness about death. Given the varying levels of lethality for different methods used in suicide attempts, an important question is if different levels of fearlessness about death are needed for specific methods. The central aim of this study was to test whether various methods for suicide are associated with different levels of fearlessness about death in a large sample of suicide attempt survivors. Participants were 620 suicide attempt survivors from active military, veteran, and civilian populations. Suicide attempt status was confirmed by two independent raters coding qualitative accounts and participants indicating at least one past attempt with intent to die on other survey items. Results indicated that fearlessness about death does not differ by attempt method and that nearly all methods are statistically equivalent to one another. Despite several methods requiring significantly more time facing mortal fear and severe physical anguish (e.g., cutting, hanging/asphyxiation), as well as certain means being much more lethal (e.g., firearm), differences in ability to enact a suicide attempt with a particular method was not associated with fearlessness about death. This may further indicate the importance of clinicians focusing on practical capability aspects (e.g., means safety, access, comfort with method) with patients at an increased risk for suicide.

Use of the acquired capability for suicide scale (ACSS) among United States military and Veteran samples: A systematic review

BACKGROUND

Military personnel and Veterans are at increased risk for suicide. Theoretical and conceptual arguments have suggested that elevated levels of acquired capability (AC) could be an explanatory factor accounting for this increased risk. However, empirical research utilizing the Acquired Capability for Suicide Scale (ACSS) in military populations has yielded mixed findings.

METHODS

To better ascertain what factors are associated with AC, and whether methodological limitations may be contributing to mixed findings, a systematic review was conducted.

RESULTS

A total of 31 articles utilized the ACSS to examine factors associated with AC, including combat history, in United States (U.S.) military personnel and Veterans. Nearly all studies (96.8%) were rated high risk of bias. Use of the ACSS varied, with seven different iterations utilized. Nearly all studies examined correlations between the ACSS and sample characteristics, mental health and clinical factors, Interpersonal Theory of Suicide constructs, and/or suicide-specific variables. Results of higher-level analyses, dominated by cross-sectional designs, often contradicted correlational findings, with inconsistent findings across studies.

LIMITATIONS

Included studies were non-representative of all U.S. military and Veteran populations and may only generalize to these populations.

CONCLUSIONS

Due to the high risk of bias, inconsistent use of the ACSS, lack of sample heterogeneity, and variability in factors examined, interpretation of current ACSS empirical data is cautioned. Suggestions for future research, contextualized by these limitations, are discussed.

Establishing the psychometric properties and construct validity of the Painful and Provocative Events Scale-Revised

BACKGROUND

Engagement in painful and provocative events is central to hypotheses for how capability for suicide develops. However, the existing measure of painful and provocative events is not psychometrically sound. We developed a measure with improved psychometric properties: the Painful and Provocative Events Scale (PPES)-Revised.

METHOD

In study 1, 447 adults (53.5% women, mean age = 35.4 years) answered 77 items describing painful and/or provocative experiences. Exploratory factor analysis (EFA) was performed. In study 2, 403 adults (55.1% women, mean age = 38.1 years) answered the retained items and confirmatory factor analysis (CFA) was performed. The scale's factorial invariance across gender was examined. Estimates of convergent and discriminant validity were obtained.

RESULTS

EFA yielded a two-factor structure, which was confirmed with CFA. The factor structure was invariant across men and women. Estimates of convergent and discriminant validity were promising.

LIMITATIONS

Limitations include non-weighted items, additional need for CFA among high-risk groups, lack of assessment of person-specific painful and provocative events, and need for prospective research to establish the scale's predictive validity.

CONCLUSIONS

By assessing painful and provocative events more uniformly and reliably than the existing measure, the PPES-Revised has the potential to advance the understanding of capability for suicide.

Do suicide attempters and suicide ideators differ in capability for suicide?

Suicide ideation is a prerequisite for suicide attempts. However, the majority of ideators will never act on their thoughts. It is therefore crucial to understand what differentiates those who consider suicide from those who attempt suicide. The aim of this study was to investigate the role of different aspects of capability for suicide (fearlessness about death, subjective pain tolerance, objective pain persistence) in differentiating suicide ideators from suicide attempters, single attempters from multiple attempters and recent attempters from distant attempters. A total of 308 psychiatric inpatients (53.6% female; age: M=36.92, SD=14.30) suffering from suicide ideation with or without lifetime suicide attempts were compared regarding fearlessness about death, subjective pain tolerance and objective pain persistence (assessed with a pressure algometer). No differences in fearlessness about death, subjective pain tolerance and objective pain persistence were found in suicide ideators vs. attempters, single vs. multiple attempters and recent vs. distant attempters. It might be presumed that fearlessness about death, subjective pain tolerance and objective pain persistence do not offer useful information for the differentiation between suicide ideators and attempters, however, there are several limitations to take into account. Further effort is needed to understand more clearly what differentiates suicide ideators from suicide attempters.

Tolerance for psychological pain and capability for suicide: Contributions to suicidal ideation and behavior

Among people with suicide ideation most do not attempt suicide or die by suicide. In this online study of adult US Facebook users (n = 219), we examined capability for suicide, operationalized as fearlessness about death, and tolerance for psychological pain as potential variables that may explain why some people move from suicide ideation to suicidal behavior. Tolerance for psychological pain was significantly higher for participants who had never attempted suicide. Fearlessness about death was higher in participants who had attempted suicide, but not significantly. At high levels of psychological pain, one's belief in the ability to cope with psychological pain, a dimension of tolerance for psychological pain, was lower in participants with a history of suicide attempt than in participants who had never attempted suicide. The odds of suicidal desire were almost cut in half with each unit increase in participants' belief in their coping ability, whereas for each unit increase in fearlessness about death, the odds of suicidal desire increased by 65%. The Pearson correlation between tolerance for psychological pain and fearlessness about death was negligible. Our findings support a role for both tolerance for psychological pain and capability for suicide/fearlessness about death in the ideation-to-action framework of suicide.

Rising longitudinal trajectories in suicide rates: The role of firearm suicide rates and firearm legislation

Firearms account for approximately half of all US suicide deaths each year despite being utilized in only a small minority of suicide attempts. We examined the extent to which overall suicide rates fluctuated relative to firearm and non-firearm suicide rates across a period of 16years (1999-2015). We further tested the notion of means substitution by examining the association between firearm suicide rates and non-firearm suicide rates. Lastly, we examined the extent to which the presence of specific laws related to handgun ownership previously shown cross-sectionally to be associated with lower suicide rates (universal background checks, mandatory waiting periods) were associated with an attenuated trajectory in suicide rates across the study period. As anticipated, whereas decreases in firearm suicide rates were associated with decreases in overall suicide rates (b=0.46, SE=0.07, p<0.001), decreases in firearm suicides were not associated with off-setting increases in suicides by other methods (b=-0.04, SE=0.05, p=0.36). Furthermore, the absence of universal background check (b=0.12, SE=0.05, p=0.028) and mandatory waiting period (b=0.16, SE=0.06, p=0.008) laws was associated with a more steeply rising trajectory of statewide suicide rates. These results mitigate concerns regarding means substitution and speak to the potential high yield impact of systematically implemented means safety prevention efforts focused on firearms.

Cross-cultural relevance of the Interpersonal Theory of suicide across Korean and U.S. undergraduate students

This study investigated the cross-cultural relevance and validity of the Interpersonal Theory of Suicide (ITS) utilizing young adult samples from South Korea (n =554) and the United States (U.S.; n =390). To examine the ITS, all participants completed self-report questionnaires measuring Thwarted Belongingness, Perceived Burdensomeness, and Capability for Suicide. We examined whether each construct significantly predicted the severity of suicidal risk in both samples. We also determined whether the strength of the effects of Thwarted Belongingness and Perceived Burdensomeness on suicidal ideation differed between the two samples due to the greater degree of importance placed on interpersonal relationships in collectivistic cultures such as South Korea. Structural equation modeling was used to examine these hypotheses. Thwarted Belongingness, Perceived Burdensomeness, and Capability for Suicide significantly predicted elevated suicidal risk. However, there were no significant differences in the paths from Thwarted Belongingness or Perceived Burdensomeness to suicide risk between the South Korean and U.S.

SAMPLES

These findings support the cross-cultural relevance and applicability of the ITS, whereby Thwarted Belongingness and Perceived Burdensomeness serve as indicators of suicide risk in both Western (U.S.) and East Asian (Korean) samples.

A test of the interpersonal-psychological theory of suicide among arrested domestic violence offenders

Little is known about risk factors for suicide ideation and attempts among domestic violence offenders. Guided by the interpersonal-psychological theory of suicide, this cross-sectional study examined risk factors for suicide ideation and attempts among 312 men and 84 women arrested for domestic violence and mandated to attend batterer intervention programs. Men reported greater capability for suicide, but no gender differences were found in perceived burdensomeness and thwarted belongingness. After controlling for correlates of suicide ideation, perceived burdensomeness-but not thwarted belongingness or its interaction with perceived burdensomeness-associated with suicide ideation. Suicide attempters exhibited greater perceived burdensomeness, drug use and problems, borderline personality disorder symptoms, depressive symptoms, and suicide ideation, but not capability for suicide, than nonattempters. Gender did not moderate the associations of the IPTS constructs with suicide ideation and attempts. These findings parallel tests of the interpersonal-psychological theory in other samples. Additional work is needed to identify factors that distinguish risk for suicide ideation from risk for suicide attempts among domestic violence offenders.

Capability for suicide interacts with states of heightened arousal to predict death by suicide beyond the effects of depression and hopelessness

BACKGROUND

States of heightened arousal (e.g., agitation, sleep disturbance) have been repeatedly linked to suicidal thoughts and behaviors, including attempts and death. Studies have further indicated that these states may be particularly pernicious among individuals who evidence high suicidal capability. The objective of this study was to examine the interactive effects of heightened arousal and the capability for suicide in the prospective prediction of death by suicide. We examine this relation beyond the effects of robust predictors of suicide, namely depression and hopelessness.

METHODS

Participants were drawn from a larger study of undergraduates who completed baseline assessments during their freshman year and were then followed to time of death. The sample in this study only included individuals who had died by suicide (n=96) or other causes (n=542). Proxy measures to assess predictor variables were constructed using items from the MMPI, which was administered at baseline. An independent sample of clinical outpatients (n=was used to evaluate the construct validity of the proxy measures).

RESULTS

Results were in line with expectation: heightened arousal interacted with capability for suicide to prospectively predict death by suicide, such that, as severity of heightened arousal symptoms increased, the likelihood of death by suicide increased among individuals high but not low on capability for suicide.

LIMITATIONS

Limitations include the use of proxy measures, the extended length of follow-up, and the homogeneity of the sample (i.e., primarily White males).

CONCLUSION

These findings add to an emerging literature that supports the moderating influence of capability for suicide on the relationship between states of heightened arousal on the likelihood of death by suicide.