Executive Functioning and Suicidal Behavior Among Veterans With and Without a History of Traumatic Brain Injury

Impulsivity and Psychiatric Diagnoses as Mediators of Suicidal Ideation and Suicide Attempts Among Veterans With Traumatic Brain Injury

OBJECTIVE

Traumatic brain injury (TBI) is a risk factor for suicide, but questions related to mechanisms remain unanswered. Impulsivity is a risk factor for suicide and is a common sequela of TBI. The authors explored the relationships between TBI and both suicidal ideation and suicide attempts and explored whether impulsivity and comorbid psychiatric diagnoses mediate these relationships.

METHODS

This cross-sectional retrospective chart review study included 164 veterans enrolled in a previous study. Sixty-nine veterans had no TBI history, and 95 had a TBI history (mild, N=44; moderate, N=13; severe, N=12; and unclear severity, N=26). To examine the associations between TBI and suicidal ideation or suicide attempts, as well as potential mediators of these relationships, chi-square tests, t tests, and logistic regression models were used.

RESULTS

Unadjusted analyses indicated that veterans with TBI were more likely to report suicidal ideation; however, in analyses controlling for mediators, this relationship was no longer significant. Among veterans with TBI, suicidal ideation was related most strongly to high impulsivity (odds ratio=15.35, 95% CI=2.43-96.79), followed by depression (odds ratio=5.73, 95% CI=2.53-12.99) and posttraumatic stress disorder (odds ratio=2.57, 95% CI=1.03-6.42). TBI was not related to suicide attempts, yet suicide attempts were related to high impulsivity (odds ratio=6.95, 95% CI=1.24-38.75) and depression (odds ratio=3.89, 95% CI=1.56-9.40).

CONCLUSIONS

These findings suggest that impulsivity, followed by psychiatric diagnoses, most strongly mediate the relationships between TBI and both suicidal ideation and suicide attempts. Impulsivity may be mechanistically related to, and serve as a future treatment target for, suicidality among veterans with TBI.

A practical introduction to using the drift diffusion model of decision-making in cognitive psychology, neuroscience, and health sciences

Recent years have seen a rapid increase in the number of studies using evidence-accumulation models (such as the drift diffusion model, DDM) in the fields of psychology and neuroscience. These models go beyond observed behavior to extract descriptions of latent cognitive processes that have been linked to different brain substrates. Accordingly, it is important for psychology and neuroscience researchers to be able to understand published findings based on these models. However, many articles using (and explaining) these models assume that the reader already has a fairly deep understanding of (and interest in) the computational and mathematical underpinnings, which may limit many readers' ability to understand the results and appreciate the implications. The goal of this article is therefore to provide a practical introduction to the DDM and its application to behavioral data - without requiring a deep background in mathematics or computational modeling. The article discusses the basic ideas underpinning the DDM, and explains the way that DDM results are normally presented and evaluated. It also provides a step-by-step example of how the DDM is implemented and used on an example dataset, and discusses methods for model validation and for presenting (and evaluating) model results. Supplementary material provides R code for all examples, along with the sample dataset described in the text, to allow interested readers to replicate the examples themselves. The article is primarily targeted at psychologists, neuroscientists, and health professionals with a background in experimental cognitive psychology and/or cognitive neuroscience, who are interested in understanding how DDMs are used in the literature, as well as some who may to go on to apply these approaches in their own work.

A Systematic Review of Behavior-Outcome Psychological Assessments as Correlates of Suicidality

AIM

Identifying correlates of suicidality is an important goal for suicide researchers because these correlates may predict suicidal behaviors. Psychological tasks that assess sensitivity to the outcomes of actions (i.e., consequence-based learning) have been commonly used by researchers seeking to identify correlates of suicidality. This is likely due to the straightforward integration of the tasks within most theoretical frameworks for understanding suicidality. Contextual factors have been shown to have a substantial effect on responding in behavior-outcome tasks. However, the direct relevance of these factors as determinants of behavior in suicide research is not clear. Thus, the purpose of this review was to assess the role of context in tasks involving behavior-outcome relations in suicide research.

METHODS

Four databases were searched using terms from general learning theory. Articles that featured evaluation of tasks with hypothetical or real outcomes to differentiate suicidality were included.

RESULTS

Eighty-two studies met inclusion criteria. Across studies there were 27 different tasks. Most instances of tasks across studies involved rewards (76.9%), while others emphasized punishment (15.7%), social (5.6%), or virtual suicide (1.8%) outcomes. Differentiation of suicidality was detected by 43.4%, 64.7%, 83.3%, and 50% of tasks featuring reward, punishment, social contexts, and virtual suicide respectively. All but five studies were retrospective.

CONCLUSION

Tasks that more closely mimic contexts and outcomes related to suicide appear to produce more pronounced differentiation of people with suicidality from people without suicidality. The lack of prospective designs is an important limitation of the literature.HIGHLIGHTSTasks that involve punishment or social outcomes better discriminate suicidality.Reward-based tasks are overused in suicide research.The conditioning hypothesis of suicidality is closely aligned with the literature.Only 5 of 82 studies incorporated prospective measures.

White matter integrity, suicidal ideation, and cognitive dysfunction in combat-exposed Iraq and Afghanistan Veterans

White matter alterations in frontolimbic circuits and poorer cognitive functioning have been observed in individuals endorsing suicidality across numerous psychiatric conditions. However, relationships between white matter integrity, cognition, and suicidality in Veterans are poorly understood, particularly for those at increased risk for suicide due to mental health conditions (e.g., posttraumatic stress disorder, depression) and traumatic brain injury history. We (1) examined white matter alterations in combat-exposed Iraq/Afghanistan Veterans with and without suicidal ideation (SI) and (2) investigated relationships between white matter integrity and neuropsychological functioning in regions that differed between SI groups. No group differences were found regarding psychiatric diagnoses. Participants with SI had lower fractional anisotropy (FA) in the posterior corona radiata, superior corona radiata, and superior longitudinal fasciculus relative to those without SI. Worse processing speed/attention performance was associated with lower FA in the superior longitudinal fasciculus, while worse executive functioning performance was associated with lower FA in the superior corona radiata and superior longitudinal fasciculus. Memory performance was not associated with FA. These findings suggest that white matter integrity may be involved in cognitive dysfunction and increased risk for SI. Interventions that target cognitive dysfunction may ameliorate SI, and in turn, reduce risk for suicide among Veterans.

Decision-making in suicidal behavior: A systematic review and meta-analysis

Impaired decision-making (DM) is well-known in suicidal behavior (SB). We aimed to review the evidence on DM and its mediating factors in SB and perform a meta-analysis on DM assessed using the Iowa Gambling Task (IGT). We conducted a search on databases of papers published on DM and SB up to 2020: 46 studies were included in the systematic review, and 18 in the meta-analysis. For meta-analysis, we compared DM performance between suicide attempters (SAs) and patients (PCs) or healthy controls (HCs). The systematic review showed that SAs have greater difficulties in all DM domains. The meta-analysis found worse IGT performance among SAs in comparison with PCs and HCs. A meta-regression did not find differences for age, gender, psychiatric disorder, and clinical status. Our findings indicate that SAs exhibited deficits in DM under conditions of risk though not ambiguity. Worse DM was independent of age, gender, psychiatric disorder, and suggested that DM impairment could be considered a cognitive trait of suicidal vulnerability, a risk factor and an attribute of SAs.

Risky decision-making in suicide attempters, and the choice of a violent suicidal means: an updated meta-analysis

BACKGROUND

Studies showed disadvantageous decision-making in suicide attempters. The present meta-analysis aims to examine the stability of these findings and related questions.

METHODS

EMBASE and Pubmed databases were searched for studies published between 01/01/2000 and 01/01/2020 with an additional search through bibliographical references. English or French articles published in peer-reviewed journals, reporting quantitative task-based measures of decision-making in suicide attempters were included: 3,582 records were identified, 33 full-text articles screened, and 21 articles finally included.

RESULTS

All studies were conducted in mood disorders; 18 used the Iowa Gambling Task (IGT) and 3 the Cambridge Gamble Task (CGT). With the IGT, suicide attempters showed riskier choices than patient controls (Hedges' g=-0.28 95%CI (-0.44 - -0.12)) and healthy controls (g=-0.54 (-0.83 - -0.25)) with no significant difference between control groups. The difference between suicide attempters and patient controls was not related to age group, mood disorder type, author, or research center while an effect of time of publication was found (p=0.006). Poorer performance was also found in suicide attempters compared to patient controls when using the CGT (g=-0.57 95%CI (-0.82 - -0.31)). Suicide attempters who used a violent means showed poorer IGT performance than those who used a non-violent means (3 studies).

LIMITATION

Limited number of studies outside mood disorders. No data to calculate a gender effect.

CONCLUSION

The present meta-analysis confirmed riskier decision-making in suicide attempters. Although group differences appear to be of modest effect size in general, they were particularly marked in the subgroup of those who used a violent suicidal means.

Factors Increasing Risk of Suicide after Traumatic Brain Injury: A State-of-the-Science Review of Military and Civilian Studies

Primary Objective: Survey TBI literature to identify evidence of risk for post-injury suicide.Literature Selection: Search terms ((traumatic brain injury OR TBI) AND (suicidality OR suicidal behaviour OR suicidal ideation)) entered in PubMed, OVID Medline, PsychInfo, and Web of Science for papers published in print 01/01/1997 to 06/30/2019.Analysis of Literature: Authors screened abstracts, excluding duplicates and articles not meeting inclusion/exclusion criteria. Full papers were reviewed to make final exclusions. Data were extracted from 40 papers included co- and premorbid disorders, demographics, injury-related and psychological factors.Results: Persons with TBI have a higher risk for suicide than the general population. Reviewed articles reported comorbid depression and/or PTSD as risk factors for post-TBI suicide. Co- or premorbid substance misuse, sex, and sleep disturbance moderate risk. Quality of the literature was limited by sample size, the predominance of male participants, and inconsistency in reporting of findings.Conclusions: Comorbid depression and PTSD are significant post-TBI risk factors for suicide. Several variables combine to moderate or mediate TBI's connection with suicide. Civilian and military clinician cross-talk and consistent reporting of results from reproducible studies of post-TBI suicide risk factors could improve prevention and treatment efforts in veterans and civilians.

Assessment of Executive Function in Patients with Traumatic Brain Injury with the Wisconsin Card-Sorting Test

This review aimed at providing a brief and comprehensive summary of recent research regarding the use of the Wisconsin Card-Sorting Test (WCST) to assess executive function in patients with traumatic brain injury (TBI). A bibliographical search, performed in PubMed, Web of Science, Scopus, Cochrane Library, and PsycInfo, targeted publications from 2010 to 2020, in English or Spanish. Information regarding the studies’ designs, sample features and use of the WCST scores was recorded. An initial search eliciting 387 citations was reduced to 47 relevant papers. The highest proportion of publications came from the United States of America (34.0%) and included adult patients (95.7%). Observational designs were the most frequent (85.1%), the highest proportion being cross-sectional or case series studies. The average time after the occurrence of the TBI ranged from 4 to 62 years in single case studies, and from 6 weeks up to 23.5 years in the studies with more than one patient. Four studies compared groups of patients with TBI according to the severity (mild, moderate and/or severe), and in two cases, the studies compared TBI patients with healthy controls. Randomized control trials were seven in total. The noncomputerized WCST version including 128 cards was the most frequently used (78.7%). Characterization of the clinical profile of participants was the most frequent purpose (34.0%). The WCST is a common measure of executive function in patients with TBI. Although shorter and/or computerized versions are available, the original WCST with 128 cards is still used most often. The WCST is a useful tool for research and clinical purposes, yet a common practice is to report only one or a few of the possible scores, which prevents further valid comparisons across studies. Results might be useful to professionals in the clinical and research fields to guide them in assessment planning and proper interpretation of the WCST scores.

Towards the objective assessment of suicidal states: Some neurocognitive deficits may be temporally related to suicide attempt

Neurocognitive detection of suicidal states has the potential to significantly advance objective risk assessment. This goal requires establishing that neurocognitive deficits fluctuate around the time of a suicide attempt. The current study therefore evaluated whether neurocognitive performance is temporally related to suicide attempt, in a sample at highrisk for suicide (n = 141). Evaluations consisted of a clinician-administered interview, self-report questionnaires, and neurocognitive tasks assessing response inhibition, attentional control, and memory recognition. Analyses examined whether neurocognitive scores significantly differed according to the following temporal suicide attempt categories: (a) past-week attempt; (b) past-year attempt (not in past week); and (c) no past-year attempt. Univariate results showed that response inhibition and memory recognition were significantly related to suicide attempt recency. Post-hoc pairwise tests showed that participants with a past-week suicide attempt showed greater impairments than those without a past-year attempt. Multivariate tests showed the same pattern of results, adjusting for age, suicide attempts prior to past year, mood disturbance, and suicidal ideation. These results show that neurocognitive assessment of response inhibition and memory recognition shows sensitivity to the recency of a suicide attempt. While future prospective studies are needed, results suggest that phasic neurocognitive deficits may serve as objective markers of short-term suicide risk.

Mild Traumatic Brain Injury Burden Moderates the Relationship Between Cognitive Functioning and Suicidality in Iraq/Afghanistan-Era Veterans

OBJECTIVES

Suicidal ideation (SI) is highly prevalent in Iraq/Afghanistan-era veterans with a history of mild traumatic brain injury (mTBI), and multiple mTBIs impart even greater risk for poorer neuropsychological functioning and suicidality. However, little is known about the cognitive mechanisms that may confer increased risk of suicidality in this population. Thus, we examined relationships between neuropsychological functioning and suicidality and specifically whether lifetime mTBI burden would moderate relationships between cognitive functioning and suicidal ideation.

METHODS

Iraq/Afghanistan-era Veterans with a history of mTBI seeking outpatient services (N = 282) completed a clinical neuropsychological assessment and psychiatric and postconcussive symptom questionnaires.

RESULTS

Individuals who endorsed SI reported more severe post-traumatic stress disorder (PTSD), depression, and postconcussive symptoms and exhibited significantly worse memory performance compared to those who denied SI. Furthermore, mTBI burden interacted with both attention/processing speed and memory, such that poorer performance in these domains was associated with greater likelihood of SI in individuals with a history of three or more mTBIs. The pattern of results remained consistent when controlling for PTSD, depression, and postconcussive symptoms.

CONCLUSIONS

Slowed processing speed and/or memory difficulties may make it challenging to access and use past experiences to solve current problems and imagine future outcomes, leading to increases in hopelessness and SI in veterans with three or more mTBIs. Results have the potential to better inform treatment decisions for veterans with history of multiple mTBIs. (JINS, 2019, 25, 79-89).

Development and content validity of the behavioral assessment screening tool (BASTβ)

PURPOSE

Develop and establish the content validity of the Behavioral Assessment Screening Tool (BAST_β), a self-reported measure of behavioral and emotional symptoms after traumatic brain injury.

METHODS

This was an assessment development study, including two focus groups of individuals with traumatic brain injury (n = 11) and their family members (n = 10) and an expert panel evaluation of content validity by experts in traumatic brain injury rehabilitation (n = 7). We developed and assessed the Content Validity Index of the BAST_β.

RESULTS

The BAST_β initial items (n = 77) corresponded with an established conceptual model of behavioral dysregulation after traumatic brain injury. After expert panel evaluation and focus group feedback, the final BAST_β included 66 items (60 primary, 6 branching logic) rated on a three-level ordinal scale (Never, Sometimes, Always) with reference to the past two weeks, and an Environmental Context checklist including recent major life events (n = 23) and four open-ended questions about environmental factors. The BAST_β had a high Content Validity Index of 89.3%.

CONCLUSION

The BAST_β is a theoretically grounded, multidimensional self-reported assessment of behavioral dysregulation after traumatic brain injury, with good content validity. Future translation into mobile health modalities could improve effectiveness and efficiency of long-term symptom monitoring post-traumatic brain injury. Future work will establish and validate the factor structure, internal consistency reliabilities and other validities of the BAST. Implications for Rehabilitation Behavioral problems after traumatic brain injury is one of the strongest contributing factors to poor mood and community integration outcomes after injury. Behavior is complex and multidimensional, making it a challenge to measure and to monitor long term. The Behavioral Assessment Screening Tool (BAST) is a patient-oriented outcome assessment developed in collaboration with individuals with traumatic brain injury, their care partners, and experts in the field of traumatic brain injury rehabilitation to be relevant and accessible for adults with traumatic brain injuries. The BAST is a long-term monitoring and screening tool for community-dwelling adults with traumatic brain injuries, to improve identification and management of behavioral and emotional sequelae.

A behavioral and cognitive neuroscience perspective on impulsivity, suicide, and non-suicidal self-injury: Meta-analysis and recommendations for future research

We conducted a meta-analysis of neurobehavioral and neurocognitive indices of impulsivity in relation to suicidal thoughts and behaviors, as well as non-suicidal self-injury (NSSI). In our systematic review, 34 studies were identified and submitted to a random-effects meta-analysis. A small pooled effect size was observed for the association between behavioral impulsivity and NSSI (OR=1.34, p<0.05). A small-to-medium pooled effect size (OR=2.23, p<0.001) was found for the association between behavioral impulsivity and suicide attempts, and a medium-to-large pooled effect size was observed for this outcome in relation to cognitive impulsivity (OR=3.14, p<0.01). Length of time between suicide attempt and impulsivity assessment moderated the strength of the relation between impulsivity and attempts, with a large pooled effect size (OR=5.54, p<0.001) evident when the suicide attempt occurred within a month of behavioral impulsivity assessment. Studies of clinically significant NSSI temporally proximal to impulsivity assessment are needed. Longitudinal research is required to clarify the prognostic value of behavioral and cognitive impulsivity for short-term risk for self-harm.

Animal models to improve our understanding and treatment of suicidal behavior

Worldwide, suicide is a leading cause of death. Although a sizable proportion of deaths by suicide may be preventable, it is well documented that despite major governmental and international investments in research, education and clinical practice suicide rates have not diminished and are even increasing among several at-risk populations. Although nonhuman animals do not engage in suicidal behavior amenable to translational studies, we argue that animal model systems are necessary to investigate candidate endophenotypes of suicidal behavior and the neurobiology underlying these endophenotypes. Animal models are similarly a critical resource to help delineate treatment targets and pharmacological means to improve our ability to manage the risk of suicide. In particular, certain pathophysiological pathways to suicidal behavior, including stress and hypothalamic-pituitary-adrenal axis dysfunction, neurotransmitter system abnormalities, endocrine and neuroimmune changes, aggression, impulsivity and decision-making deficits, as well as the role of critical interactions between genetic and epigenetic factors, development and environmental risk factors can be modeled in laboratory animals. We broadly describe human biological findings, as well as protective effects of medications such as lithium, clozapine, and ketamine associated with modifying risk of engaging in suicidal behavior that are readily translatable to animal models. Endophenotypes of suicidal behavior, studied in animal models, are further useful for moving observed associations with harmful environmental factors (for example, childhood adversity, mechanical trauma aeroallergens, pathogens, inflammation triggers) from association to causation, and developing preventative strategies. Further study in animals will contribute to a more informed, comprehensive, accelerated and ultimately impactful suicide research portfolio.

Mild traumatic brain injury and suicide risk among a clinical sample of deployed military personnel: Evidence for a serial mediation model of anger and depression

Research has demonstrated a robust link between traumatic brain injuries (TBIs) and suicide risk. Yet, few studies have investigated factors that account for this link. Utilizing a clinical sample of deployed military personnel, this study aimed to examine a serial meditation model of anger and depression in the association of mild TBI and suicide risk. A total of 149 military service members referred for evaluation/treatment of a suspected head injury at a military hospital participated in the present study (92.6% male; M_age = 27.9y). Self-report measures included the Suicidal Behaviors Questionnaire-Revised (SBQ-R), Automated Neuropsychological Assessment Metrics (ANAM) anger and depression subscales, and Behavioral Health Measure-20 depression subscale. A current mild TBI diagnosis was confirmed by a licensed clinical psychologist/physician. Overall, 84.6% (126/149) of participants met diagnostic criteria for a current mild TBI. Bootstrapped serial mediation analyses indicated that the association of mild TBI and suicide risk is serially mediated by anger and depression symptoms (bias-corrected 95% confidence interval [CI] for the indirect effect = 0.044, 0.576). An alternate serial mediation model in which depression symptoms precede anger was not statistically significant (bias-corrected 95% CI for the indirect effect = -0.405, 0.050). Among a clinical sample of military personnel, increased anger and depression statistically mediated the association of mild TBI and suicide risk, and anger appears to precede depression in this pathway. Findings suggest that therapeutically targeting anger may serve to thwart the trajectory to suicide risk among military personnel who experience a mild TBI. Future research should investigate this conjecture within a prospective design to establish temporality.