Contextual Effects of Traumatic Brain Injury on the Connectome: Differential Effects of Deployment- and Non–Deployment-Acquired Injuries

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BackgroundBehavioral dyscontrol occurs commonly in the general population and in United States service members and Veterans (SM/V). This condition merits special attention in SM/V, particularly in the aftermath of deployments. Military deployments frequently give rise to posttraumatic stress disorder (PTSD) and deployment-related mild TBI traumatic brain injury (TBI), potentially leading to manifestations of behavioral dyscontrol.ObjectiveExamine associations among PTSD symptom severity, deployment-related mild traumatic brain injury, and behavioral dyscontrol among SM/V.DesignSecondary cross-sectional data analysis from the Long-Term Impact of Military-Relevant Brain Injury Consortium – Chronic Effects of Neurotrauma Consortium prospective longitudinal study among SM/V (N = 1,808).MethodsUnivariable and multivariable linear regression models assessed the association and interaction effects between PTSD symptom severity, as assessed by the PTSD Checklist for the Diagnostic and Statistical Manual, 5th edition (PCL-5), and deployment-related mild TBI on behavioral dyscontrol, adjusting for demographics, pain, social support, resilience, and general self-efficacy.ResultsAmong the 1,808 individuals in our sample, PTSD symptom severity (B = 0.23, 95% CI: 0.22, 0.25, p < 0.001) and deployment-related mild TBI (B = 3.27, 95% CI: 2.63, 3.90, p < 0.001) were significantly associated with behavioral dyscontrol in univariable analysis. Interaction effects were significant between PTSD symptom severity and deployment mild TBI (B = −0.03, 95% CI: −0.06, −0.01, p = 0.029) in multivariable analysis, indicating that the effect of mild TBI on behavioral dyscontrol is no longer significant among those with a PCL-5 score > 22.96.ConclusionResults indicated an association between PTSD symptom severity, deployment-related mild TBI, and behavioral dyscontrol among SM/V. Notably, the effect of deployment-related mild TBI was pronounced for individuals with lower PTSD symptom severity. Higher social support scores were associated with lower dyscontrol, emphasizing the potential for social support to be a protective factor. General self-efficacy was also associated with reduced behavioral dyscontrol.

Section: Resultsmentioning

confidence: 99%

Mild traumatic brain injury, PTSD symptom severity, and behavioral dyscontrol: a LIMBIC-CENC study

Stromberg,

Martindale,

Walker

et al. 2024

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“…MEG data from 30 healthy Veteran participants were obtained from a separate study [Chronic Effects of Neurotrauma Consortium Study 34 (56,(63)(64)(65)] and were used as a control group for the current study. In this study, 8 mins of resting state data were acquired in the seated position with eyes open.…”

Section: Patientsmentioning

confidence: 99%

“…The SAM Z-score is a ratio of source power to noise variance for a given voxel that is analogous to the z-deviate (77, 80). SAM was applied in the following frequency ranges: delta (DC-4 Hz), theta (4-8 Hz), alpha (8-13 Hz), beta (13-30 Hz), and gamma , as well as DC-80 Hz (56,63,64). The magnitudes and coordinates for all local Z-score maxima, or peaks, in each frequency map were extracted.…”

Section: Meg Analysismentioning

confidence: 99%

“…Finally, through the use of magnetic source imaging (MSI), biomagnetic activity can be directly localized in brain space (58,62). Despite these advantages, the use of MEG in TBI research has focused predominantly on mild or moderate TBI (56,(63)(64)(65)(66)(67)(68)(69)(70), with only two reports on patients with severe brain injury (31,71).…”

Section: Introductionmentioning

confidence: 99%

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Use of magnetic source imaging to assess recovery after severe traumatic brain injury—an MEG pilot study

Sarma,

Popli,

Anzalone

et al. 2023

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RationaleSevere TBI (sTBI) is a devastating neurological injury that comprises a significant global trauma burden. Early comprehensive neurocritical care and rehabilitation improve outcomes for such patients, although better diagnostic and prognostic tools are necessary to guide personalized treatment plans.MethodsIn this study, we explored the feasibility of conducting resting state magnetoencephalography (MEG) in a case series of sTBI patients acutely after injury (~7 days), and then about 1.5 and 8 months after injury. Synthetic aperture magnetometry (SAM) was utilized to localize source power in the canonical frequency bands of delta, theta, alpha, beta, and gamma, as well as DC–80 Hz.ResultsAt the first scan, SAM source maps revealed zones of hypofunction, islands of preserved activity, and hemispheric asymmetry across bandwidths, with markedly reduced power on the side of injury for each patient. GCS scores improved at scan 2 and by scan 3 the patients were ambulatory. The SAM maps for scans 2 and 3 varied, with most patients showing increasing power over time, especially in gamma, but a continued reduction in power in damaged areas and hemispheric asymmetry and/or relative diminishment in power at the site of injury. At the group level for scan 1, there was a large excess of neural generators operating within the delta band relative to control participants, while the number of neural generators for beta and gamma were significantly reduced. At scan 2 there was increased beta power relative to controls. At scan 3 there was increased group-wise delta power in comparison to controls.ConclusionIn summary, this pilot study shows that MEG can be safely used to monitor and track the recovery of brain function in patients with severe TBI as well as to identify patient-specific regions of decreased or altered brain function. Such MEG maps of brain function may be used in the future to tailor patient-specific rehabilitation plans to target regions of altered spectral power with neurostimulation and other treatments.

“…Although they are not well characterized, greater damage to hippocampal neurons and periventricular parenchyma rather than diffuse axonal injury have been suggested ( 10 ). Recent work has also demonstrated differences in the functional connectomes of Veterans with deployment-related versus non-deployment mild TBI that may explain some differences in behavioral outcomes ( 11 ).…”

Section: Introductionmentioning

confidence: 99%

Subcortical functional connectivity and its association with walking performance following deployment related mild TBI

Newsome,

Martindale,

Davenport

et al. 2023

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IntroductionThe relation between traumatic brain injury (TBI), its acute and chronic symptoms, and the potential for remote neurodegenerative disease is a priority for military research. Structural and functional connectivity (FC) of the basal ganglia, involved in motor tasks such as walking, are altered in some samples of Service Members and Veterans with TBI, but any behavioral implications are unclear and could further depend on the context in which the TBI occurred.MethodsIn this study, FC from caudate and pallidum seeds was measured in Service Members and Veterans with a history of mild TBI that occurred during combat deployment, Service Members and Veterans whose mild TBI occurred outside of deployment, and Service Members and Veterans who had no lifetime history of TBI.ResultsFC patterns differed for the two contextual types of mild TBI. Service Members and Veterans with deployment-related mild TBI demonstrated increased FC between the right caudate and lateral occipital regions relative to both the non-deployment mild TBI and TBI-negative groups. When evaluating the association between FC from the caudate and gait, the non-deployment mild TBI group showed a significant positive relationship between walking time and FC with the frontal pole, implicated in navigational planning, whereas the deployment-related mild TBI group trended towards a greater negative association between walking time and FC within the occipital lobes, associated with visuo-spatial processing during navigation.DiscussionThese findings have implications for elucidating subtle motor disruption in Service Members and Veterans with deployment-related mild TBI. Possible implications for future walking performance are discussed.