Discriminating Mild Traumatic Brain Injury and Posttraumatic Stress Disorder Using Latent Neuroimaging and Neuropsychological Profiles in Active-Duty Military Service Members

Traumatic brain injury: Symptoms to systems in the 21st century

Severe traumatic brain injury (TBI) is a devastating injury with a mortality of ∼ 25-30 %. Despite decades of high-quality research, no drug therapy has reduced mortality. Why is this so? We argue two contributing factors for the lack of effective drug therapies include the use of specific-pathogen free (SPF) animals for translational research and the flawed practice of single-nodal targeting for drug design. A revolution is required to better understand how the whole body responds to TBI, identify new markers of its progression, and discover new system-acting drugs to treat it. In this review, we present a brief history of TBI, discuss its system's pathophysiology and propose a new research strategy for the 21st century. TBI progression develops from injury signals radiating from the primary impact, which can cause local ischemia, hemorrhage, excitotoxicity, cellular depolarization, immune dysfunction, sympathetic hyperactivity, blood-brain barrier breach, coagulopathy and whole-body dysfunction. Metabolic reprograming of immune cells drives neuroinflammation and secondary injury processes. We propose if sympathetic hyperactivity and immune cell activation can be corrected early, cardiovascular function and endothelial-glycocalyx-mitochondrial coupling can be restored, and secondary injury minimized with improved patient outcomes. The therapeutic goal is to switch the injury phenotype to a healing phenotype by restoring homeostasis and maintaining sufficient tissue O2 delivery. We have been developing a small-volume fluid therapy comprising adenosine, lidocaine and magnesium (ALM) to treat TBI and have shown that it blunts the CNS-stress response, supports cardiovascular function and reduces secondary injury. Future research will investigate its suitability for human translation.

Neuropsychological Profiles of Deployment-Related Mild Traumatic Brain Injury: A LIMBIC-CENC Study

BACKGROUND AND OBJECTIVES

Traumatic brain injury (TBI) is a concern for US service members and veterans (SMV), leading to heterogeneous psychological and cognitive outcomes. We sought to identify neuropsychological profiles of mild TBI (mTBI) and posttraumatic stress disorder (PTSD) among the largest SMV sample to date.

METHODS

We analyzed cross-sectional baseline data from SMV with prior combat deployments enrolled in the ongoing Long-term Impact of Military-relevant Brain Injury Consortium-Chronic Effects of Neurotrauma Consortium prospective longitudinal study. Latent profile analysis identified symptom profiles using 35 indicators, including physical symptoms, depression, quality of life, sleep quality, postconcussive symptoms, and cognitive performance. It is important to note that the profiles were determined independently of mTBI and probable PTSD status. After profile identification, we examined associations between demographic variables, mTBI characteristics, and PTSD symptoms with symptom profile membership.

RESULTS

The analytic sample included 1,659 SMV (mean age 41.1 ± 10.0 years; 87% male); among them 29% (n = 480) had a history of non-deployment-related mTBI only, 14% (n = 239) had deployment-related mTBI only, 36% (n = 602) had both non-deployment and deployment-related mTBI, and 30% (n = 497) met criteria for probable PTSD. A 6-profile model had the best fit, with separation on all indicators (p < 0.001). The model revealed distinct neuropsychological profiles, representing a combination of 3 self-reported functioning patterns: high (HS), moderate (MS), and low (LS), and 2 cognitive performance patterns: high (HC) and low (LC). The profiles were (1) HS/HC: n=301, 18.1%; (2) HS/LC: n=294, 17.7%; (3) MS/HC: n=359, 21.6%; (4) MS/LC: n=316, 19.0%; (5) LS/HC: n=228, 13.7%; and (6) LS/LC: n=161, 9.7%. SMV with deployment-related mTBI tended to be grouped into lower functioning profiles and were more likely to meet criteria for probable PTSD. Conversely, SMV with no mTBI exposure or non-deployment-related mTBI were clustered in higher functioning profiles and had a lower likelihood of meeting criteria for probable PTSD.

DISCUSSION

Findings suggest varied symptom and functional profiles in SMV, influenced by injury context and probable PTSD comorbidity. Despite diagnostic challenges, comprehensive assessment of functioning and cognition can detect subtle differences related to mTBI and PTSD, revealing distinct neuropsychological profiles. Prioritizing early treatment based on these profiles may improve prognostication and support efficient recovery.

Long Noncoding RNA VLDLR-AS1 Levels in Serum Correlate with Combat-Related Chronic Mild Traumatic Brain Injury and Depression Symptoms in US Veterans

More than 75% of traumatic brain injuries (TBIs) are mild (mTBI) and military service members often experience repeated combat-related mTBI. The chronic comorbidities concomitant with repetitive mTBI (rmTBI) include depression, post-traumatic stress disorder or neurological dysfunction. This study sought to determine a long noncoding RNA (lncRNA) expression signature in serum samples that correlated with rmTBI years after the incidences. Serum samples were obtained from Long-Term Impact of Military-Relevant Brain-Injury Consortium Chronic Effects of Neurotrauma Consortium (LIMBIC CENC) repository, from participants unexposed to TBI or who had rmTBI. Four lncRNAs were identified as consistently present in all samples, as detected via droplet digital PCR and packaged in exosomes enriched for CNS origin. The results, using qPCR, demonstrated that the lncRNA VLDLR-AS1 levels were significantly lower among individuals with rmTBI compared to those with no lifetime TBI. ROC analysis determined an AUC of 0.74 (95% CI: 0.6124 to 0.8741; p = 0.0012). The optimal cutoff for VLDLR-AS1 was ≤153.8 ng. A secondary analysis of clinical data from LIMBIC CENC was conducted to evaluate the psychological symptom burden, and the results show that lncRNAs VLDLR-AS1 and MALAT1 are correlated with symptoms of depression. In conclusion, lncRNA VLDLR-AS1 may serve as a blood biomarker for identifying chronic rmTBI and depression in patients.