Head injury as a predictor of psychological outcome in combat veterans

Diet's Impact on Post-Traumatic Brain Injury Depression: Exploring Neurodegeneration, Chronic Blood-Brain Barrier Destruction, and Glutamate Neurotoxicity Mechanisms

Traumatic brain injury (TBI) has a profound impact on cognitive and mental functioning, leading to lifelong impairment and significantly diminishing the quality of life for affected individuals. A healthy blood-brain barrier (BBB) plays a crucial role in guarding the brain against elevated levels of blood glutamate, making its permeability a vital aspect of glutamate regulation within the brain. Studies have shown the efficacy of reducing excess glutamate in the brain as a treatment for post-TBI depression, anxiety, and aggression. The purpose of this article is to evaluate the involvement of dietary glutamate in the development of depression after TBI. We performed a literature search to examine the effects of diets abundant in glutamate, which are common in Asian populations, when compared to diets low in glutamate, which are prevalent in Europe and America. We specifically explored these effects in the context of chronic BBB damage after TBI, which may initiate neurodegeneration and subsequently have an impact on depression through the mechanism of chronic glutamate neurotoxicity. A glutamate-rich diet leads to increased blood glutamate levels when contrasted with a glutamate-poor diet. Within the context of chronic BBB disruption, elevated blood glutamate levels translate to heightened brain glutamate concentrations, thereby intensifying neurodegeneration due to glutamate neurotoxicity.

Cumulative Effect of Head Injuries on Nonmotor Outcomes in Parkinson's Disease

OBJECTIVE

Parkinson's disease (PD) is a neurodegenerative movement disorder that is a result of dopamine depletion in the basal ganglia. Individuals with a PD diagnosis experience motor symptoms (e.g., tremors) and nonmotor symptoms (e.g., cognitive decline). Previous studies suggest that progression of cognitive dysfunction in other neurologic populations can be predicted by cumulative head injuries. The study examined the association between lifelong number of head injuries and nonmotor outcomes (cognitive complaints, depression, and quality of life).

METHODS

Participants consisted of 3,483 individuals with PD diagnoses who were enrolled in the Fox Insight study. Participants completed a self-report questionnaire to quantify the number of head injuries experienced throughout life. Participants also completed measures of nonmotor outcomes (cognitive complaints, depression, and quality of life) every 6 months over a 3-year period.

RESULTS

Cognitive complaints were more common among those experiencing more head injuries. Further, more severe depression and greater difficulties in quality of life were reported among individuals experiencing a greater number of head injuries. Additional analyses revealed the effect between cognitive complaints and number of head injuries was driven by individuals who experienced five or more head injuries in their lifetime.

CONCLUSIONS

Among individuals with PD, a patient report of past head injuries may have prognostic implications for important nonmotor outcomes. Report of multiple head injuries may be particularly concerning.

Characterizing the Risk of Depression Following Mild Traumatic Brain Injury: A Meta-Analysis of the Literature Comparing Chronic mTBI to Non-mTBI Populations

Objective: Mild traumatic brain injury (mTBI) is associated with depressed mood acutely post-injury, but there is little evidence regarding long-term depression. The aim of this study was to determine the odds ratio (OR) of depression chronically following mTBI.

Methods: We searched Medline (PubMed), ProQuest, and Web of Science from date of database creation to January 23, 2019, for eligible studies examining depression at least 6 months post-injury in adult subjects with mTBI of any etiology, including civilians and military. Three authors independently reviewed titles and abstracts for study eligibility. Data were extracted and collated by two investigators. Risk of bias was assessed with the SIGN methodology. Study data were pooled using random-effects meta-analysis. The primary exposure was mTBI, and the primary outcome was depression. Secondary exploratory variables were time of assessment, age at injury, age at assessment, sex, and etiology.

Results: We included 47 cross-sectional studies (n = 25,103 mTBI and 29,982 control), 26 cohort studies (n = 70,119 mTBI, 262,034 control), four prospective observational studies (n = 1,058 mTBI and 733 control), two prospective longitudinal studies (n = 119 mTBI, 81 control), two case-control studies (n = 56 mTBI, 56 control), and one randomized controlled trial (n = 252 mTBI, 3,214 control). mTBI was associated with a 3.29-fold increased risk of depression (OR 3.29, 95% CI 2.68–4.03, I² = 96%). The OR for depression did not change when subjects were assessed at 6–12 months (OR 2.43, 1.45–4.07), years 1–2 (OR 4.12, 2.10–8.07); 2–10 (OR 3.28, 2.42–4.46), or 10+ (OR 3.42, 1.51–7.77). Similar risk of depression was sustained across different age at injury (<25: OR 2.26, 1.82–2.81; 25–35: OR 4.67, 3.06–7.14; >35: OR 2.69, 1.42–5.10) and different age at assessment (<40 years: OR 3.14, 2.48–3.99; >40 years: OR 4.57, 2.54–8.24). Female sex had a non-significant increase in OR (OR 19.97, 2.39–166.93) compared to male (OR 3.0, 2.33–3.86). mTBI etiology had no impact on depression.

Conclusions: Those experiencing mTBI are more than three times more likely to experience depression compared to those without a history of mTBI, and this risk remains decades beyond the mTBI event. Future longitudinal studies are needed to identify and mitigate this risk.

An extension of olfactometry methods: An expandable, fully automated, mobile, MRI-compatible olfactometer

BACKGROUND

fMRI experiments on olfaction offer new insights into the complex, but in contrast to other sensory systems, less studied cognition of odors. To perform these experiments is still a challenge.

NEW METHOD

To address the challenge posed by MR settings, an olfactometer design is presented including specific improvements to the limited number of already existing olfactometers. Innovative features such as pneumatically controlled pinch valves, useable in the scanner and providing exact stimulus timing as well as a 3D-printed nasal mask inlet for common sleep laboratory masks that can be used for lateral divided stimulus presentation are introduced. To ensure a fully automated and mobile system, the use of a flexible and easily-adapted Matlab-Code and a portable adaptable container system are presented.

RESULTS

The functional efficiency of these features are proven by results of an fMRI study as well as testing temporal resolution and concentration stability with a mass spectrometer.

COMPARISON WITH EXISTING METHODS

The 24-channel olfactometer design presented here provides an inexpensive alternative to the currently available olfactometers including the achievement of fast onset times, lateral divided stimulus presentation and high flexibility and adaptability to different scientific questions.

CONCLUSION

The olfactometer design presented in this paper can be seen as a realistic and feasible solution to overcome the challenges of presenting olfactory stimuli within the MR setting.

The mental health sequelae of traumatic head injury in South Vietnamese ex-political detainees who survived torture

Little is known about the relationship between traumatic head injury (THI) and psychiatric morbidity in torture survivors. We examine the relationship between THI and depression, PTSD, post-concussive syndrome (PCS), disability and poor health status in Vietnamese ex-political detainees who survived incarceration in Vietnamese re-education camps. A community sample of ex-political detainees (n=337) and a non-THI, non-ex-detainee comparison group (n=82) were surveyed. Seventy-eight percent of the ex-political detainees had experienced THI; 90.6% of the ex-political detainees and 3.6% of the comparison group had experienced 7 or more trauma events. Depression and PTSD were greater in ex-detainees than in the comparison group (40.9% vs 23.2% and 13.4% vs 0%). Dose-effect relationships for THI and trauma/torture in the ex-political detainee group were significant. Logistic regression in the pooled sample of ex-detainees and the comparison group confirmed the independent impact of THI from trauma/torture on psychiatric morbidity (OR for PTSD=22.4; 95% CI: 3.0-165.8). These results demonstrate important effects of THI on depression and PTSD in Vietnamese ex-detainees who have survived torture.

Methods for olfactory fMRI studies: Implication of respiration

Human olfactory system is under-studied using fMRI compared with other sensory systems. Because the perception (intensity, threshold, and valence) and detection of odors are tightly involved with respiration, the subject's respiration pattern modulates and interacts with the experimental paradigm, which presents difficulties for olfactory fMRI data acquisition, post-processing, and interpretation. Based on our investigation on the interactions of odor presentation and subject's respiration, we propose a respiration-triggered event-related olfactory fMRI technique and a data post-processing method that effectively captures precise onsets of olfactory blood-oxygen-level-dependent (BOLD) signal in the primary olfactory cortex. We compared the olfactory BOLD signals from seventeen normal healthy adults with diverse respiratory patterns and showed that the subjects' respiratory patterns modulated the olfactory stimulation paradigm, which significantly confounded the BOLD signal. The presented experimental technique provides a simple and effective means for generating reliable olfactory fMRI results.

Predictors of psychiatric disorders in combat veterans

BACKGROUND

Most previous research that has examined mental health among Operation Enduring Freedom and Operation Iraqi Freedom (OEF/OIF) combatants has relied on self-report measures to assess mental health outcomes; few studies have examined predictors of actual mental health diagnoses. The objective of this longitudinal investigation was to identify predictors of psychiatric disorders among Marines who deployed to combat in Iraq and Afghanistan.

METHODS

The study sample consisted of 1113 Marines who had deployed to Iraq or Afghanistan. Demographic and psychosocial predictor variables from a survey that all Marines in the sample had completed were studied in relation to subsequent psychiatric diagnoses. Univariate and multivariate logistic regression were used to determine the influence of the predictors on the occurrence of psychiatric disorders.

RESULTS

In a sample of Marines with no previous psychiatric disorder diagnoses, 18% were diagnosed with a new-onset psychiatric disorder. Adjusting for other variables, the strongest predictors of overall psychiatric disorders were female gender, mild traumatic brain injury symptoms, and satisfaction with leadership. Service members who expressed greater satisfaction with leadership were about half as likely to develop a mental disorder as those who were not satisfied. Unique predictors of specific types of mental disorders were also identified.

CONCLUSIONS

Overall, the study's most relevant result was that two potentially modifiable factors, low satisfaction with leadership and low organizational commitment, predicted mental disorder diagnoses in a military sample. Additional research should aim to clarify the nature and impact of these factors on combatant mental health.

Detection of blast-related traumatic brain injury in U.S. military personnel

BACKGROUND

Blast-related traumatic brain injuries have been common in the Iraq and Afghanistan wars, but fundamental questions about the nature of these injuries remain unanswered.

METHODS

We tested the hypothesis that blast-related traumatic brain injury causes traumatic axonal injury, using diffusion tensor imaging (DTI), an advanced form of magnetic resonance imaging that is sensitive to axonal injury. The subjects were 63 U.S. military personnel who had a clinical diagnosis of mild, uncomplicated traumatic brain injury. They were evacuated from the field to the Landstuhl Regional Medical Center in Landstuhl, Germany, where they underwent DTI scanning within 90 days after the injury. All the subjects had primary blast exposure plus another, blast-related mechanism of injury (e.g., being struck by a blunt object or injured in a fall or motor vehicle crash). Controls consisted of 21 military personnel who had blast exposure and other injuries but no clinical diagnosis of traumatic brain injury.

RESULTS

Abnormalities revealed on DTI were consistent with traumatic axonal injury in many of the subjects with traumatic brain injury. None had detectable intracranial injury on computed tomography. As compared with DTI scans in controls, the scans in the subjects with traumatic brain injury showed marked abnormalities in the middle cerebellar peduncles (P<0.001), in cingulum bundles (P=0.002), and in the right orbitofrontal white matter (P=0.007). In 18 of the 63 subjects with traumatic brain injury, a significantly greater number of abnormalities were found on DTI than would be expected by chance (P<0.001). Follow-up DTI scans in 47 subjects with traumatic brain injury 6 to 12 months after enrollment showed persistent abnormalities that were consistent with evolving injuries.

CONCLUSIONS

DTI findings in U.S. military personnel support the hypothesis that blast-related mild traumatic brain injury can involve axonal injury. However, the contribution of primary blast exposure as compared with that of other types of injury could not be determined directly, since none of the subjects with traumatic brain injury had isolated primary blast injury. Furthermore, many of these subjects did not have abnormalities on DTI. Thus, traumatic brain injury remains a clinical diagnosis. (Funded by the Congressionally Directed Medical Research Program and the National Institutes of Health; ClinicalTrials.gov number, NCT00785304.).

Predictors of emotional distress reported by soldiers in the combat zone

OBJECTIVE

Few studies have examined rates of distress of military personnel during deployment to a war zone. Our study sought to (a) identify rates of self-reported posttraumatic stress disorder (PTSD) and depression symptoms during combat deployment, (b) characterize higher order dimensions of emotional distress experienced by soldiers during deployment, and (c) identify predictors of these dimensions of emotional distress.

METHOD

Participants were 2677 National Guard soldiers deployed as part of Operation Iraqi Freedom in 2006-07. We performed a principal components factor analysis on items of the PTSD Checklist - Military Version and the Beck Depression Inventory to identify dimensions of emotional distress, followed by multiple regression analyses to identify factors that predicted these dimensions of distress.

RESULTS

Rates of PTSD and depression in our sample were 7% and 9%, respectively. Five dimensions of emotional distress emerged: negative affect/cognitions, trauma-specific re-experiencing and avoidance, vegetative symptoms, loss of interest/numbing symptoms, and arousal/irritability. Two dimensions, trauma-specific symptoms and arousal/irritability, appeared to be more indicative of trauma sequelae, while the other three dimensions were more indicative of depressive symptoms. Demographic factors, combat exposure (including injury and exposure to explosive blast), and attitudinal variables predicted trauma-specific aspects of distress. Symptoms characteristic of depression or generalized distress were predicted by female gender, recent prior deployment, and attitudinal factors but were not predicted by blast exposure or injury.

CONCLUSIONS

These findings suggest specific targets for contextual and individual interventions to reduce deployment-related distress and point out the need for longitudinal follow-up to determine long-term implications for post-deployment functioning.

Mild traumatic brain injury and posttraumatic stress disorder in returning veterans: perspectives from cognitive neuroscience

A significant proportion of military personnel deployed in support of Operation Enduring Freedom (OEF) and Operation Iraqi Freedom (OIF) has been exposed to war-zone events potentially associated with traumatic brain injury (TBI) and posttraumatic stress disorder (PTSD). There has been significant controversy regarding healthcare policy for those service members and military veterans who returned from OEF/OIF deployments with both mild TBI and PTSD. There is currently little empirical evidence available to address these controversies. This review uses a cognitive neuroscience framework to address the potential impact of mild TBI on the development, course, and clinical management of PTSD. The field would benefit from research efforts that take into consideration the potential differential impact of mild TBI with versus without persistent cognitive deficits, longitudinal work examining the trajectory of PTSD symptoms when index trauma events involve TBI, randomized clinical trials designed to examine the impact of mild TBI on response to existing PTSD treatment interventions, and development and examination of potential treatment augmentation strategies.

[Comorbidity of posttraumatic stress disorder and mild closed head injury in war veterans: endocrinological and psychological profiles]

AIM

To determine the degree of psychological and endocrinological changes in war veterans with the diagnosis of Chronic Posttraumatic Stress Disorder (PTSD) regarding presence/absence of comorbid mild closed head injury (mCHI) caused by explosive devices.

METHODS

Two groups of PTSD inpatients, with (n = 37), and without (n = 86) sustained blast trauma followed by mCHI were formed during the psychiatric treatment. Participants were interviewed by experienced clinicians who used the PTSD Interview (PTSD-I). In addition, patients completed the Symptom Checklist-90-Revised (SCL-90-R). Serum levels of ten hormones were assessed: triiodothyronine, thyroxine, thyrotropin-stimulating hormone, prolactin, luteinizing hormone, follicle-stimulating hormone, and insulin, by radioimmunoassays and hydrocortisone, growth hormone and testosterone by fluoroimmunoassays.

RESULTS

Veterans with comorbid mCHI and PTSD showed significantly higher level of amnesia for traumatic event as well as of somatization on the SCL-90-R. Significant differences of hormone levels were not found.

CONCLUSION

The results didn't support the hypothesis on specific PTSD subgroup characterized by history of mCHI and consecutive postconcussion syndrome. The absence of differences in levels of hormones indicated the dominant role of psychogenic trauma in the etiology of hormone disbalance in chronic PTSD. Amnesia for traumatic event in war veterans with comorbid PTSD and mCHI was easily explained by neurogenic peritraumatic amnesia due to the blast trauma, but it did not affect either quality of intensity or posttraumatic symptoms as well as endocrinological parameters.

Psychiatric effects of traumatic brain injury events in Cambodian survivors of mass violence

BACKGROUND

The prevalence of brain injury and its effects in populations exposed to war violence has not been studied in recent years.

AIMS

To examine the association between traumatic brain injury events and psychiatric symptoms of major depression and post-traumatic stress disorder (PTSD) in Cambodian survivors of mass violence.

METHOD

The population comprised a multi-stage random sample of Cambodian refugees living in a Thai refugee camp. The main results analysed the relationship between six categories of trauma events and psychiatric symptoms of depression and PTSD during two time periods.

RESULTS

Almost 15 000 trauma events were reported (n=13 481, Pol Pot period; n=1249, past year). Traumatic brain injury was most common in the highly educated and in individuals with the highest levels of cumulative trauma. Of all trauma categories, traumatic brain injury revealed the strongest association with symptoms of depression, and a weaker association with PTSD. Brain injury represented 4% of the total number of traumatic events for both time periods, contributing 20% of the total symptom score for depression and 8% of that for PTSD.

CONCLUSIONS

Clinical identification and treatment of traumatic brain injuries in highly traumatised populations must be maintained in order to develop a new public health model for their treatment.

Attention, learning, and memory performances and intellectual resources in Vietnam veterans: PTSD and no disorder comparisons

Attention, learning, memory, and estimated intellectual potential were examined in 26 Vietnam veterans diagnosed with posttraumatic stress disorder (PTSD) and in 21 Vietnam veterans without mental disorders. Results revealed PTSD-associated cognitive deficits on tasks of sustained attention, working memory, initial learning, and estimated premorbid intelligence but not on measures of focus of attention, shift of attention, or memory savings. Cognitive task performances adjusted for estimated native intelligence remained negatively correlated with PTSD severity. An intellectual measure adjusted for cognitive task performances was negatively correlated with PTSD severity, even after the authors statistically controlled the level of combat exposure. Results suggested that although intellectual resources may constitute a vulnerability-protective factor for PTSD development, PTSD was associated with cognitive impairment independent of intellectual functioning.