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Rowland JA, Martindale SL. Considerations for the assessment of blast exposure in service members and veterans. Front Neurol 2024; 15:1383710. [PMID: 38685944 PMCID: PMC11056521 DOI: 10.3389/fneur.2024.1383710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Accepted: 03/29/2024] [Indexed: 05/02/2024] Open
Abstract
Introduction Blast exposure is an increasingly present occupational hazard for military service members, particularly in modern warfare scenarios. The study of blast exposure in humans is limited by the lack of a consensus definition for blast exposure and considerable variability in measurement. Research has clearly demonstrated a robust and reliable effect of blast exposure on brain structure and function in the absence of other injury mechanisms. However, the exact mechanisms underlying these outcomes remain unclear. Despite clear contributions from preclinical studies, this knowledge has been slow to translate to clinical applications. The present manuscript empirically demonstrates the consequences of variability in measurement and definition across studies through a re-analysis of previously published data from the Chronic Effects of Neurotrauma Study 34. Methods Definitions of blast exposure used in prior work were examined including Blast TBI, Primary Blast TBI, Pressure Severity, Distance, and Frequency of Exposure. Outcomes included both symptom report and cognitive testing. Results Results demonstrate significant differences in outcomes based on the definition of blast exposure used. In some cases the same definition was strongly related to one type of outcome, but unrelated to another. Discussion The implications of these results for the study of blast exposure are discussed and potential actions to address the major limitations in the field are recommended. These include the development of a consensus definition of blast exposure, further refinement of the assessment of blast exposure, continued work to identify relevant mechanisms leading to long-term negative outcomes in humans, and improved education efforts.
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Affiliation(s)
- Jared A. Rowland
- Salisbury VA Healthcare System, Salisbury, NC, United States
- Veterans Integrated Service Network (VISN)-6 Mid-Atlantic Mental Illness, Research Education and Clinical Center (MIRECC), Durham, NC, United States
- Wake Forest School of Medicine, Winston-Salem, NC, United States
| | - Sarah L. Martindale
- Salisbury VA Healthcare System, Salisbury, NC, United States
- Veterans Integrated Service Network (VISN)-6 Mid-Atlantic Mental Illness, Research Education and Clinical Center (MIRECC), Durham, NC, United States
- Wake Forest School of Medicine, Winston-Salem, NC, United States
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Lippa SM, Bailie JM, French LM, Brickell TA, Lange RT. Lifetime blast exposure is not related to cognitive performance or psychiatric symptoms in US military personnel. Clin Neuropsychol 2024:1-23. [PMID: 38494345 DOI: 10.1080/13854046.2024.2328881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Accepted: 03/05/2024] [Indexed: 03/19/2024]
Abstract
Objective: The present study aimed to examine the impact of lifetime blast exposure (LBE) on neuropsychological functioning in service members and veterans (SMVs). Method: Participants were 282 SMVs, with and without history of traumatic brain injury (TBI), who were prospectively enrolled in a Defense and Veterans Brain Injury Center (DVBIC)-Traumatic Brain Injury Center of Excellence (TBICoE) Longitudinal TBI Study. A cross-sectional analysis of baseline data was conducted. LBE was based on two factors: Military Occupational Speciality (MOS) and SMV self-report. Participants were divided into three groups based on LBE: Blast Naive (n = 61), Blast + Low Risk MOS (n = 96), Blast + High Risk MOS (n = 125). Multivariate analysis of variance (MANOVA) was used to examine group differences on neurocognitive domains and the Minnesota Multiphasic Personality Inventory-2 Restructured Form. Results: There were no statistically significant differences in attention/working memory, processing speed, executive functioning, and memory (Fs < 1.75, ps > .1, ηp2s < .032) or in General Cognition (Fs < 0.95, ps > .3, ηp2s < .008). Prior to correction for covariates, lifetime blast exposure was related to Restructured Clinical (F(18,542) = 1.77, p = .026, ηp2 = .055), Somatic/Cognitive (F(10,550) = 1.99, p = .033, ηp2 = .035), and Externalizing Scales (F(8,552) = 2.17, p = .028, ηp2 = .030); however, these relationships did not remain significant after correction for covariates (Fs < 1.53, ps > .145, ηp2s < .032). Conclusions: We did not find evidence of a relationship between LBE and neurocognitive performance or psychiatric symptoms. This stands in contrast to prior studies demonstrating an association between lifetime blast exposure and highly sensitive blood biomarkers and/or neuroimaging. Overall, findings suggest the neuropsychological impact of lifetime blast exposure is minimal in individuals remaining in or recently retired from military service.
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Affiliation(s)
- Sara M Lippa
- National Intrepid Center of Excellence, Walter Reed National Military Medical Center, Bethesda, MD, USA
- Uniformed Services University of the Health Sciences, Bethesda, MD, USA
| | - Jason M Bailie
- Traumatic Brain Injury Center of Excellence, Bethesda, MD, USA
- Naval Hospital Camp Pendleton, Oceanside, CA, USA
- General Dynamics Information Technology, Fairfax, VA, USA
| | - Louis M French
- National Intrepid Center of Excellence, Walter Reed National Military Medical Center, Bethesda, MD, USA
- Uniformed Services University of the Health Sciences, Bethesda, MD, USA
- Traumatic Brain Injury Center of Excellence, Bethesda, MD, USA
| | - Tracey A Brickell
- National Intrepid Center of Excellence, Walter Reed National Military Medical Center, Bethesda, MD, USA
- Uniformed Services University of the Health Sciences, Bethesda, MD, USA
- Traumatic Brain Injury Center of Excellence, Bethesda, MD, USA
- General Dynamics Information Technology, Fairfax, VA, USA
| | - Rael T Lange
- National Intrepid Center of Excellence, Walter Reed National Military Medical Center, Bethesda, MD, USA
- Uniformed Services University of the Health Sciences, Bethesda, MD, USA
- Traumatic Brain Injury Center of Excellence, Bethesda, MD, USA
- General Dynamics Information Technology, Fairfax, VA, USA
- Department of Psychiatry, University of British Columbia, Vancouver, BC, Canada
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Elder GA, Gama Sosa MA, De Gasperi R, Perez Garcia G, Perez GM, Abutarboush R, Kawoos U, Zhu CW, Janssen WGM, Stone JR, Hof PR, Cook DG, Ahlers ST. The Neurovascular Unit as a Locus of Injury in Low-Level Blast-Induced Neurotrauma. Int J Mol Sci 2024; 25:1150. [PMID: 38256223 PMCID: PMC10816929 DOI: 10.3390/ijms25021150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 01/11/2024] [Accepted: 01/11/2024] [Indexed: 01/24/2024] Open
Abstract
Blast-induced neurotrauma has received much attention over the past decade. Vascular injury occurs early following blast exposure. Indeed, in animal models that approximate human mild traumatic brain injury or subclinical blast exposure, vascular pathology can occur in the presence of a normal neuropil, suggesting that the vasculature is particularly vulnerable. Brain endothelial cells and their supporting glial and neuronal elements constitute a neurovascular unit (NVU). Blast injury disrupts gliovascular and neurovascular connections in addition to damaging endothelial cells, basal laminae, smooth muscle cells, and pericytes as well as causing extracellular matrix reorganization. Perivascular pathology becomes associated with phospho-tau accumulation and chronic perivascular inflammation. Disruption of the NVU should impact activity-dependent regulation of cerebral blood flow, blood-brain barrier permeability, and glymphatic flow. Here, we review work in an animal model of low-level blast injury that we have been studying for over a decade. We review work supporting the NVU as a locus of low-level blast injury. We integrate our findings with those from other laboratories studying similar models that collectively suggest that damage to astrocytes and other perivascular cells as well as chronic immune activation play a role in the persistent neurobehavioral changes that follow blast injury.
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Affiliation(s)
- Gregory A. Elder
- Neurology Service, James J. Peters Department of Veterans Affairs Medical Center, 130 West Kingsbridge Road, Bronx, NY 10468, USA
- Department of Neurology, Icahn School of Medicine at Mount Sinai, One Gustave Levy Place, New York, NY 10029, USA;
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, One Gustave Levy Place, New York, NY 10029, USA; (M.A.G.S.); (R.D.G.)
- Mount Sinai Alzheimer’s Disease Research Center and the Ronald M. Loeb Center for Alzheimer’s Disease, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; (C.W.Z.); (P.R.H.)
| | - Miguel A. Gama Sosa
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, One Gustave Levy Place, New York, NY 10029, USA; (M.A.G.S.); (R.D.G.)
- General Medical Research Service, James J. Peters Department of Veterans Affairs Medical Center, Bronx, NY 10468, USA
| | - Rita De Gasperi
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, One Gustave Levy Place, New York, NY 10029, USA; (M.A.G.S.); (R.D.G.)
- Research and Development Service, James J. Peters Department of Veterans Affairs Medical Center, 130 West Kingsbridge Road, Bronx, NY 10468, USA;
| | - Georgina Perez Garcia
- Department of Neurology, Icahn School of Medicine at Mount Sinai, One Gustave Levy Place, New York, NY 10029, USA;
- Research and Development Service, James J. Peters Department of Veterans Affairs Medical Center, 130 West Kingsbridge Road, Bronx, NY 10468, USA;
| | - Gissel M. Perez
- Research and Development Service, James J. Peters Department of Veterans Affairs Medical Center, 130 West Kingsbridge Road, Bronx, NY 10468, USA;
| | - Rania Abutarboush
- Department of Neurotrauma, Operational and Undersea Medicine Directorate, Naval Medical ResearchCommand, 503 Robert Grant Avenue, Silver Spring, MD 20910, USA; (R.A.); (U.K.); (S.T.A.)
- The Henry M. Jackson Foundation for the Advancement of Military Medicine Inc., Bethesda, MD 20817, USA
| | - Usmah Kawoos
- Department of Neurotrauma, Operational and Undersea Medicine Directorate, Naval Medical ResearchCommand, 503 Robert Grant Avenue, Silver Spring, MD 20910, USA; (R.A.); (U.K.); (S.T.A.)
- The Henry M. Jackson Foundation for the Advancement of Military Medicine Inc., Bethesda, MD 20817, USA
| | - Carolyn W. Zhu
- Mount Sinai Alzheimer’s Disease Research Center and the Ronald M. Loeb Center for Alzheimer’s Disease, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; (C.W.Z.); (P.R.H.)
- Research and Development Service, James J. Peters Department of Veterans Affairs Medical Center, 130 West Kingsbridge Road, Bronx, NY 10468, USA;
- Department of Geriatrics and Palliative Care, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - William G. M. Janssen
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA;
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - James R. Stone
- Department of Radiology and Medical Imaging, University of Virginia, 480 Ray C Hunt Drive, Charlottesville, VA 22903, USA;
| | - Patrick R. Hof
- Mount Sinai Alzheimer’s Disease Research Center and the Ronald M. Loeb Center for Alzheimer’s Disease, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; (C.W.Z.); (P.R.H.)
- Department of Geriatrics and Palliative Care, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA;
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - David G. Cook
- Geriatric Research Education and Clinical Center, VA Puget Sound Health Care System, 1660 S Columbian Way, Seattle, WA 98108, USA;
- Department of Medicine, University of Washington, 1959 NE Pacific St., Seattle, WA 98195, USA
| | - Stephen T. Ahlers
- Department of Neurotrauma, Operational and Undersea Medicine Directorate, Naval Medical ResearchCommand, 503 Robert Grant Avenue, Silver Spring, MD 20910, USA; (R.A.); (U.K.); (S.T.A.)
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Lippa SM, Yeh PH, Kennedy JE, Bailie JM, Ollinger J, Brickell TA, French LM, Lange RT. Lifetime Blast Exposure Is Not Related to White Matter Integrity in Service Members and Veterans With and Without Uncomplicated Mild Traumatic Brain Injury. Neurotrauma Rep 2023; 4:827-837. [PMID: 38156076 PMCID: PMC10754347 DOI: 10.1089/neur.2023.0043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2023] Open
Abstract
This study examines the impact of lifetime blast exposure on white matter integrity in service members and veterans (SMVs). Participants were 227 SMVs, including those with a history of mild traumatic brain injury (mTBI; n = 124), orthopedic injury controls (n = 58), and non-injured controls (n = 45), prospectively enrolled in a Defense and Veterans Brain Injury Center (DVBIC)/Traumatic Brain Injury Center of Excellence (TBICoE) study. Participants were divided into three groups based on number of self-reported lifetime blast exposures: none (n = 53); low (i.e., 1-9 blasts; n = 81); and high (i.e., ≥10 blasts; n = 93). All participants underwent diffusion tensor imaging (DTI) at least 11 months post-injury. Tract-of-interest (TOI) analysis was applied to investigate fractional anisotropy and mean, radial, and axial diffusivity (AD) in left and right total cerebral white matter as well as 24 tracts. Benjamini-Hochberg false discovery rate (FDR) correction was used. Regressions investigating blast exposure and mTBI on white matter integrity, controlling for age, revealed that the presence of mTBI history was associated with lower AD in the bilateral superior longitudinal fasciculus and arcuate fasciculus and left cingulum (βs = -0.255 to -0.174; ps < 0.01); however, when non-injured controls were removed from the sample (but orthopedic injury controls remained), these relationships were attenuated and did not survive FDR correction. Regression models were rerun with modified post-traumatic stress disorder (PTSD) diagnosis added as a predictor. After FDR correction, PTSD was not significantly associated with white matter integrity in any of the models. Overall, there was no relationship between white matter integrity and self-reported lifetime blast exposure or PTSD.
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Affiliation(s)
- Sara M. Lippa
- Walter Reed National Military Medical Center, Bethesda, Maryland, USA
- National Intrepid Center of Excellence, Bethesda, Maryland, USA
- Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA
| | - Ping-Hong Yeh
- Walter Reed National Military Medical Center, Bethesda, Maryland, USA
- National Intrepid Center of Excellence, Bethesda, Maryland, USA
| | - Jan E. Kennedy
- Traumatic Brain Injury Center of Excellence, Silver Spring, Maryland, USA
- Contractor, General Dynamics Information Technology, Silver Spring, Maryland, USA
- Brooke Army Medical Center, Joint Base, San Antonio, Texas, USA
| | - Jason M. Bailie
- Traumatic Brain Injury Center of Excellence, Silver Spring, Maryland, USA
- Contractor, General Dynamics Information Technology, Silver Spring, Maryland, USA
- 33 Area Branch Clinic, Camp Pendleton, California, USA
| | - John Ollinger
- Walter Reed National Military Medical Center, Bethesda, Maryland, USA
- National Intrepid Center of Excellence, Bethesda, Maryland, USA
| | - Tracey A. Brickell
- Walter Reed National Military Medical Center, Bethesda, Maryland, USA
- National Intrepid Center of Excellence, Bethesda, Maryland, USA
- Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA
- Traumatic Brain Injury Center of Excellence, Silver Spring, Maryland, USA
- Contractor, General Dynamics Information Technology, Silver Spring, Maryland, USA
| | - Louis M. French
- Walter Reed National Military Medical Center, Bethesda, Maryland, USA
- National Intrepid Center of Excellence, Bethesda, Maryland, USA
- Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA
| | - Rael T. Lange
- Walter Reed National Military Medical Center, Bethesda, Maryland, USA
- National Intrepid Center of Excellence, Bethesda, Maryland, USA
- Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA
- Traumatic Brain Injury Center of Excellence, Silver Spring, Maryland, USA
- Contractor, General Dynamics Information Technology, Silver Spring, Maryland, USA
- University of British Columbia, Vancouver, British Columbia, USA
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