Associations Between Multiple Remote Mild TBIs and Objective Neuropsychological Functioning and Subjective Symptoms in Combat-Exposed Veterans

Merritt, Victoria C.; Jurick, Sarah M.; Crocker, Laura D.; Sullan, Molly J.; Sakamoto, McKenna S; Davey, Delaney K.; Hoffman, Samantha N.; Keller, Amber V.; Jak, Amy J.

doi:10.1093/arclin/acaa006

Cited by 11 publications

(11 citation statements)

References 62 publications

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“…In the case of PCL-5 measures, individuals with multiple deployments showed consistently higher scores (median value of 7), which corresponds with greater PTSD symptomatology (58). Although well-below the threshold for clinical diagnosis (i.e., PCL-5 score ≥ 33), this observation is consistent with a large body of research suggesting a link between multiple deployments, mTBI and increasing vulnerability to developing PTSD and other mental health problems (59,60). These findings should prove useful as researchers work toward developing improved diagnostic tools for distinguishing between the effects of these three conditions that frequently overlap in this population exposed routinely to low-level blast (61,62).…”

Section: Discussionsupporting

confidence: 80%

Blast in Context: The Neuropsychological and Neurocognitive Effects of Long-Term Occupational Exposure to Repeated Low-Level Explosives on Canadian Armed Forces' Breaching Instructors and Range Staff

et al. 2020

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Currently, there is strong interest within the military to better understand the effects of long-term occupational exposure to repeated low-level blast on health and performance. To gain traction on the chronic sequelae of blast, we focused on breaching—a tactical technique for gaining entry into closed/blocked spaces by placing explosives and maintaining a calculated safe distance from the detonation. Using a cross-sectional design, we compared the neuropsychological and neurocognitive profiles of breaching instructors and range staff to sex- and age-matched Canadian Armed Forces (CAF) controls. Univariate tests demonstrated that breaching was associated with greater post-concussive symptoms (Rivermead Post Concussion Symptoms Questionnaire) and lower levels of energy (RAND SF-36). In addition, breaching instructors and range staff were slower on a test that requires moving and thinking simultaneously (i.e., cognitive-motor integration). Next, using a multivariate approach, we explored the impact of other possible sources of injury, including concussion and prior war-zone deployment on the same outcomes. Concussion history was associated with higher post-concussive scores and musculoskeletal problems, whereas deployment was associated with higher post-concussive scores, but lower energy and greater PTSD symptomatology (using PCL-5). Our results indicate that although breaching, concussion, and deployment were similarly correlated with greater post-concussive symptoms, concussion history appears to be uniquely associated with altered musculoskeletal function, whereas deployment history appears to be uniquely associated with lower energy and risk of PTSD. We argue that the broader injury context must, therefore, be considered when studying the impact of repetitive low-level explosives on health and performance in military members.

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Section: Discussionsupporting

confidence: 80%

Blast in Context: The Neuropsychological and Neurocognitive Effects of Long-Term Occupational Exposure to Repeated Low-Level Explosives on Canadian Armed Forces' Breaching Instructors and Range Staff

et al. 2020

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“…This finding is consistent with previous studies that showed military members and Veterans with multiple, rather than a single, TBI report greater levels of selfreported post-concussive symptoms. 45,46 Unfortunately, the present data did not allow for quantifying and iso lating the cumulative effects of various sources of head injury on post-concussive symptoms -a shortcoming that can be addressed in future studies. An important consideration in interpreting these results is that, aside from greater lifetime exposure to blast, breachers and snipers and controls also diff ered on other relevant dimensions of head injury.…”

Section: Discussionmentioning

confidence: 92%

Blast effects on post-concussive and mental health outcomes: Data from Canadian Armed Forces breachers and snipers

Vartanian

Rhind

Nakashima

et al. 2022

Journal of Military, Veteran and Family Health

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LAY SUMMARY There has been increasing interest in understanding the impact of blast exposure on health and performance in military members and Veterans. This phenomenon has proven difficult to study because personnel diagnosed with blast-induced mild traumatic brain injury (mTBI) typically also exhibit emotional difficulties such as posttraumatic stress disorder (PTSD), likely because the events that led to mTBI in theatre were also emotionally traumatic. In turn, this comorbidity makes it difficult to tease apart symptoms uniquely due to blast-induced mTBI or PTSD. Researchers have therefore explored surrogate settings wherein the effects of blast exposure can be assessed in an operationally realistic, yet scientifically more controlled manner, such as breacher and sniper training. To that aim, researchers administered a measure of post-concussive symptomatology and two mental health scales to breachers and snipers, as well as sex- and age-matched military controls. The breachers and snipers reported greater levels of post-concussive symptoms, but not poorer mental health outcomes. Therefore, post-concussive symptoms and mental health outcomes might be dissociable when the impact of repetitive exposure to low-level blast is assessed in the context of training and operations, rather than following warzone deployment involving primarily high-level blast exposure.

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“…These initiatives and others confirm that Veterans and Service members with mTBI often develop psychiatric disorders, including posttraumatic stress disorder (PTSD), depression, and anxiety (22)(23)(24)(25)(26). Numerous clinical studies described functional impairments in participants exposed to blast(s) years before the onset of debilitating pain, increased headaches, impaired sleep, poor motor skills, and cognitive dysfunction including reduced abilities in intelligence processing speed, visual motor integration and executive functioning (22,24,(26)(27)(28).…”

Section: Characteristics and Impact Of Blast-related Mtbi In Service ...mentioning

confidence: 90%

Perspectives on Primary Blast Injury of the Brain: Translational Insights Into Non-inertial Low-Intensity Blast Injury

et al. 2022

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Most traumatic brain injuries (TBIs) during military deployment or training are clinically “mild” and frequently caused by non-impact blast exposures. Experimental models were developed to reproduce the biological consequences of high-intensity blasts causing moderate to severe brain injuries. However, the pathophysiological mechanisms of low-intensity blast (LIB)-induced neurological deficits have been understudied. This review provides perspectives on primary blast-induced mild TBI models and discusses translational aspects of LIB exposures as defined by standardized physical parameters including overpressure, impulse, and shock wave velocity. Our mouse LIB-exposure model, which reproduces deployment-related scenarios of open-field blast (OFB), caused neurobehavioral changes, including reduced exploratory activities, elevated anxiety-like levels, impaired nesting behavior, and compromised spatial reference learning and memory. These functional impairments associate with subcellular and ultrastructural neuropathological changes, such as myelinated axonal damage, synaptic alterations, and mitochondrial abnormalities occurring in the absence of gross- or cellular damage. Biochemically, we observed dysfunctional mitochondrial pathways that led to elevated oxidative stress, impaired fission-fusion dynamics, diminished mitophagy, decreased oxidative phosphorylation, and compensated cell respiration-relevant enzyme activity. LIB also induced increased levels of total tau, phosphorylated tau, and amyloid β peptide, suggesting initiation of signaling cascades leading to neurodegeneration. We also compare translational aspects of OFB findings to alternative blast injury models. By scoping relevant recent research findings, we provide recommendations for future preclinical studies to better reflect military-operational and clinical realities. Overall, better alignment of preclinical models with clinical observations and experience related to military injuries will facilitate development of more precise diagnosis, clinical evaluation, treatment, and rehabilitation.

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Associations Between Multiple Remote Mild TBIs and Objective Neuropsychological Functioning and Subjective Symptoms in Combat-Exposed Veterans

Cited by 11 publications

References 62 publications

Blast in Context: The Neuropsychological and Neurocognitive Effects of Long-Term Occupational Exposure to Repeated Low-Level Explosives on Canadian Armed Forces' Breaching Instructors and Range Staff

Blast in Context: The Neuropsychological and Neurocognitive Effects of Long-Term Occupational Exposure to Repeated Low-Level Explosives on Canadian Armed Forces' Breaching Instructors and Range Staff

Blast effects on post-concussive and mental health outcomes: Data from Canadian Armed Forces breachers and snipers

Perspectives on Primary Blast Injury of the Brain: Translational Insights Into Non-inertial Low-Intensity Blast Injury

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