Association between neurocognitive functioning and suicide attempts in U.S. Army Soldiers

The Role of the Autonomic Nervous System in the Mediation of the Resolution of Suicidal Ideation With Electroconvulsive Therapy: A Hypothesis and Review of Heart Rate Variability Over a Course of Electroconvulsive Therapy

ABSTRACT

Longitudinal observational studies have shown a meaningful decrease in suicidal thinking and suicidal behavior after receipt of electroconvulsive therapy (ECT). The antisuicide effect of ECT may be related to success in the global relief of the presenting syndrome such as depressive or psychotic illness. However, it is possible that the antisuicide effect is specific to ECT per se, over and above the relief of the clinical syndrome. Electroconvulsive therapy is associated with many observable neurochemical and physiologic effects, and some of these may plausibly be specifically linked to an antisuicide effect. The phenomenon of physiologic hyperarousal has been named as a candidate mechanism driving the risk for suicide. Hyperarousal is associated with decreased neuropsychological executive function responsible for response inhibition and can lead to impulsive action. The level of arousal within the autonomic nervous system (ANS) can be assayed with the pupillary light reflex, electrodermal activity, or with heart rate variability (HRV). This article summarizes the literature on the effects of ECT on HRV 24 to 72 hours after a course of ECT and finds evidence for increases in HRV, which indicates lower levels of arousal in the ANS. This finding suggests that ECT-related reductions in ANS arousal, presumably with corresponding improvements in response inhibition, may be one mechanism whereby ECT reduces risk for suicide.

Hill L, Kline A, Stanley BH, Interian A. Improving the prospective prediction of a near-term suicide attempt in veterans at risk for suicide, using a go/no-go task

BACKGROUND

Neurocognitive testing may advance the goal of predicting near-term suicide risk. The current study examined whether performance on a Go/No-go (GNG) task, and computational modeling to extract latent cognitive variables, could enhance prediction of suicide attempts within next 90 days, among individuals at high-risk for suicide.

METHOD

136 Veterans at high-risk for suicide previously completed a computer-based GNG task requiring rapid responding (Go) to target stimuli, while withholding responses (No-go) to infrequent foil stimuli; behavioral variables included false alarms to foils (failure to inhibit) and missed responses to targets. We conducted a secondary analysis of these data, with outcomes defined as actual suicide attempt (ASA), other suicide-related event (OtherSE) such as interrupted/aborted attempt or preparatory behavior, or neither (noSE), within 90-days after GNG testing, to examine whether GNG variables could improve ASA prediction over standard clinical variables. A computational model (linear ballistic accumulator, LBA) was also applied, to elucidate cognitive mechanisms underlying group differences.

RESULTS

On GNG, increased miss rate selectively predicted ASA, while increased false alarm rate predicted OtherSE (without ASA) within the 90-day follow-up window. In LBA modeling, ASA (but not OtherSE) was associated with decreases in decisional efficiency to targets, suggesting differences in the evidence accumulation process were specifically associated with upcoming ASA.

CONCLUSIONS

These findings suggest that GNG may improve prediction of near-term suicide risk, with distinct behavioral patterns in those who will attempt suicide within the next 90 days. Computational modeling suggests qualitative differences in cognition in individuals at near-term risk of suicide attempt.

Attentional control deficits and suicidal ideation variability: An ecological momentary assessment study in major depression

Suicidal behavior is associated with deficits in cognitive control; however, suicidal ideation (SI), a key precursor to suicidal behavior, has been less consistently linked to neuropsychological functioning. Additionally, no study to date has examined attentional control capacities in relation to variability in suicidal ideation, defined as fluctuation in SI intensity and duration across short periods of time. Prior research suggests that suicidal individuals with highly variable SI experience greater stress-responsive increases in SI and cortisol, potentially raising risk for suicidal behavior. Here, we examined attentional control capacities associated with SI variability and severity in ninety-five subjects with major depressive disorder. Variability and severity of SI and depressive affect were quantified using Ecological Momentary Assessment (EMA) over a 7-day period. Participants completed the Continuous Performance Task (CPT) and a computerized Stroop task for assessment of attentional control. EMA SI variability was associated with greater attentional interference on the Stroop task, and this was not accounted for by severity of SI, concurrently assessed depressive affect, or baseline depression. CPT performance was not related to SI variability or intensity. Findings highlight the utility of EMA methods in characterizing patterned experiences of SI and suggest that attentional control deficits may contribute to these characteristic patterns.

Chronic Traumatic Encephalopathy in the Brains of Military Personnel

BACKGROUND

Persistent neuropsychiatric sequelae may develop in military personnel who are exposed to combat; such sequelae have been attributed in some cases to chronic traumatic encephalopathy (CTE). Only limited data regarding CTE in the brains of military service members are available.

METHODS

We performed neuropathological examinations for the presence of CTE in 225 consecutive brains from a brain bank dedicated to the study of deceased service members. In addition, we reviewed information obtained retrospectively regarding the decedents' histories of blast exposure, contact sports, other types of traumatic brain injury (TBI), and neuropsychiatric disorders.

RESULTS

Neuropathological findings of CTE were present in 10 of the 225 brains (4.4%) we examined; half the CTE cases had only a single pathognomonic lesion. Of the 45 brains from decedents who had a history of blast exposure, 3 had CTE, as compared with 7 of 180 brains from those without a history of blast exposure (relative risk, 1.71; 95% confidence interval [CI], 0.46 to 6.37); 3 of 21 brains from decedents with TBI from an injury during military service caused by the head striking a physical object without associated blast exposure (military impact TBI) had CTE, as compared with 7 of 204 without this exposure (relative risk, 4.16; 95% CI, 1.16 to 14.91). All brains with CTE were from decedents who had participated in contact sports; 10 of 60 contact-sports participants had CTE, as compared with 0 of 165 who had not participated in contact sports (point estimate of relative risk not computable; 95% CI, 6.16 to infinity). CTE was present in 8 of 44 brains from decedents with non-sports-related TBI in civilian life, as compared with 2 of 181 brains from those without such exposure in civilian life (relative risk, 16.45; 95% CI, 3.62 to 74.79).

CONCLUSIONS

Evidence of CTE was infrequently found in a series of brains from military personnel and was usually reflected by minimal neuropathologic changes. Risk ratios for CTE were numerically higher among decedents who had contact-sports exposure and other exposures to TBI in civilian life than among those who had blast exposure or other military TBI, but the small number of CTE cases and wide confidence intervals preclude causal conclusions. (Funded by the Department of Defense-Uniformed Services University Brain Tissue Repository and Neuropathology Program and the Henry M. Jackson Foundation for the Advancement of Military Medicine.).

The Role of Past Suicidal Behavior on Current Suicidality: A Retrospective Study in the Israeli Military

Past suicide attempts are a significant risk factor for future suicidality. Therefore, the present military-based study examined the past suicidal behavior of soldiers who recently made a severe suicide attempt. Our sample consisted of 65 active-duty soldiers (61.5% males), between the ages of 18 and 28 years old (M = 20.4, SD ± 1.3). The inclusion criterion was a recent severe suicide attempt, requiring at least a 24 h hospitalization. This sample was divided into two groups, according to previous suicidal behavior, namely whether their first suicide attempt was before or after enlistment (n = 25; 38.5% and n = 40; 61.5%, respectively). We then examined the lethality and intent of the recent event in regard to this division. Four measures were used to assess the subjects' suicidal characteristics: the Columbia Suicide Severity Rating Scale, the Self-Harm Behavior Questionnaire, the Suicidal Behaviors Questionnaire-Revised, and the Beck Scale for Suicide Ideation. No significant difference in the severity of the suicide attempts (either actual or potential severity) were found between those who had suicide attempts before enlistment and those who had their first attempt in the service. As a matter of fact, most of the suicide attempts that occurred for the first time during military service had used a violent method (58.3%, n = 21). Finally, using multivariate analyses, we found that current thoughts and behavior, rather than past suicidality, was the strongest predictor for the lethality of suicide attempts.