Exploring racial/ethnic disparities in rehabilitation outcomes after TBI: A veterans affairs model systems study

BACKGROUND

Almost one-third of the U.S. military population is comprised of service members and veterans (SMVs) of color. Research suggests poorer functional and psychosocial outcomes among Black and Hispanic/Latine vs. White civilians following traumatic brain injury (TBI).

OBJECTIVE

This study examined racial/ethnic differences in 5-year functional independence and life satisfaction trajectories among SMVs who had undergone acute rehabilitation at one of five VA TBI Model Systems (TBIMS) Polytrauma Rehabilitation Centers (PRCs).

METHODS

Differences in demographic and injury-related factors were assessed during acute rehabilitation among White (n = 663), Black (n = 89) and Hispanic/Latine (n = 124) groups. Functional Independence Measure (FIM) Motor, FIM Cognitive, and Satisfaction with Life Scale (SWLS) scores were collected at 1, 2, and 5 years after injury. Racial/ethnic comparisons in these outcome trajectories were made using hierarchical linear modeling.

RESULTS

Black SMVs were less likely than White and Hispanic/Latine SMVs to have been deployed to a combat zone; there were no other racial/ethnic differences in any demographic or injury-related variable assessed. In terms of outcomes, no racial/ethnic differences emerged in FIM Motor, FIM cognitive, or SWLS trajectories.

CONCLUSION

The absence of observable racial/ethnic differences in 5-year outcome trajectories after TBI among SMVs from VA TBIMS PRCs contrasts sharply with previous research identifying disparities in these same outcomes and throughout the larger VA health care system. Individuals enrolled in VA PRCs are likely homogenized on key social determinants of health that would otherwise contribute to racial/ethnic disparities in outcome trajectories.

Sex-specific analysis of traumatic brain injury events: applying computational and data visualization techniques to inform prevention and management

BACKGROUND

The interplay of host, agent, and environment implicated in traumatic brain injury (TBI) events is difficult to account for in hypothesis-driven research. Data-driven analysis of injury data can enable insight into injury events in novel ways. This research dissected complex and multidimensional data at the time of the TBI event by exploiting data mining and information visualization methods.

METHODS

We drew upon population-based decade-long health administrative data collected through the routine operation of the publicly funded health system in Ontario, Canada. We applied a computational approach to categorize health records of 235,003 patients with TBI versus the same number of reference patients without TBI, individually matched based on sex, age, place of residence, and neighbourhood income quantile. We adopted the basic concepts of the Haddon Matrix (host, agent, environment) to organize emerging factors significantly related to TBI versus non-TBI events. To explore sex differences, the data of male and female patients with TBI were plotted on heatmaps and clustered using hierarchical clustering algorithms.

RESULTS

Based on detected similarities, the computational technique yielded 34 factors on which individual TBI-event codes were loaded, allowing observation of a set of definable patterns within the host, the agent, and the environment. Differences in the patterns of host, agent and environment were found between male and female patients with TBI, which are currently not identified based on data from injury surveillance databases. The results were internally validated.

CONCLUSIONS

The study outlines novel areas for research relevant to TBI and offers insight into how computational and visual techniques can be applied to advance the understanding of TBI event. Results highlight unique aspects of sex differences of the host and agent at the injury event, as well as differences in exposure to adverse social and environmental circumstances, which can be a function of gender, aiding in future studies of injury prevention and gender-transformative care.

Network topology changes in chronic mild traumatic brain injury (mTBI)

BACKGROUND

In mild traumatic brain injury (mTBI), diffuse axonal injury results in disruption of functional networks in the brain and is thought to be a major contributor to cognitive dysfunction even years after trauma.

OBJECTIVE

Few studies have assessed longitudinal changes in network topology in chronic mTBI. We utilized a graph theoretical approach to investigate alterations in global network topology based on resting-state functional connectivity in veterans with chronic mTBI.

METHODS

50 veterans with chronic mTBI (mean of 20.7 yrs. from trauma) and 40 age-matched controls underwent two functional magnetic resonance imaging scans 18 months apart. Graph theory analysis was used to quantify network topology measures (density, clustering coefficient, global efficiency, and modularity). Hierarchical linear mixed models were used to examine longitudinal change in network topology.

RESULTS

With all network measures, we found a significant group × time interaction. At baseline, brain networks of individuals with mTBI were less clustered (p = 0.03) and more modular (p = 0.02) than those of HC. Over time, the mTBI networks became more densely connected (p = 0.002), with increased clustering (p = 0.001) and reduced modularity (p < 0.001). Network topology did not change across time in HC.

CONCLUSION

These findings demonstrate that brain networks of individuals with mTBI remain plastic decades after injury and undergo significant changes in network topology even at the later phase of the disease.

Pre-injury health status and excess mortality in persons with traumatic brain injury: A decade-long historical cohort study

An increasing number of patients are able to survive traumatic brain injuries (TBIs) with advanced resuscitation. However, the role of their pre-injury health status in mortality in the following years is not known. Here, we followed 77,088 consecutive patients (59% male) who survived the TBI event in Ontario, Canada for more than a decade, and examined the relationships between their pre-injury health status and mortality rates in excess to the expected mortality calculated using sex- and age-specific life tables. There were 5792 deaths over the studied period, 3163 (6.95%) deaths in male and 2629 (8.33%) in female patients. The average excess mortality rate over the follow-up period of 14 years was 1.81 (95% confidence interval = 1.76-1.86). Analyses of follow-up time windows showed different patterns for the average excess rate of mortality following TBI, with the greatest rates observed in year one after injury. Among identified pre-injury comorbidity factors, 33 were associated with excess mortality rates. These rates were comparable between sexes. Additional analyses in the validation dataset confirmed that these findings were unlikely a result of TBI misclassification or unmeasured confounding. Thus, detection and subsequent management of pre-injury health status should be an integral component of any strategy to reduce excess mortality in TBI patients. The complexity of pre-injury comorbidity calls for integration of multidisciplinary health services to meet TBI patients' needs and prevent adverse outcomes.

Traumatic brain injury (TBI) in collision sports: Possible mechanisms of transformation into chronic traumatic encephalopathy (CTE)

Traumatic brain injury (TBI) is a leading cause of death and disability, contributing to ~30% of all injury-related deaths in the US. TBI occurs when a force transmitted to the head causes neuropathologic damage and impairment of brain function. TBI doubles risk of suicide and is the major determinant of acquired seizure disorders. TBI arising from closed head trauma (CHT) significantly increases the risk of developing Alzheimer's disease (AD), Parkinson's disease (PD) and chronic traumatic encephalopathy (CTE). Evidence for a possible role of TBI as a risk factor for sporadic amyotrophic lateral sclerosis (sALS) has been provided by studies of professional players of European football. Depending on age, genetic make-up (in particular, being a carrier of one or two ApoE4 alleles), the number of TBIs sustained, their severity, the time periods involved, and many other factors that affect vulnerability, decades may pass after occurrence of one or more TBIs before sequelae such as AD, PD, sALS or CTE become clinically evident. Among college and professional football players who experience repeated concussions and sub-concussive blows to the head, the risk of developing CTE increases with the number of years actively devoted to the sport, and the degree of exposure to physical impacts inherent in the position played. Following a moderate or severe concussion, or a series of mild blows to the head, the brain may undergo subtle pathophysiological changes that are unlikely to be detected with confidence using available diagnostic methods. Biomarkers are being sought that can help the attending physician infer the likely presence of an ongoing occult neurodegenerative process. One example of the adverse effect of collision on the brain is "heading" the soccer ball-a feat that, repeated over years of competition, has been found to produce severe brain damage in veteran players. CTE has attracted increasing national attention because of its devastating effects in a high proportion of retired professional players of American football. In a study of brains from deceased former football players, contributed mostly by family members, CTE was neuropathologically diagnosed in 110 of 111 of National Football League (NFL) veterans. In the CTE-positive subjects, the authors observed extensive brain atrophy, astrogliosis, myelinated axonopathy, microvascular injury, perivascular neuroinflammation, and phosphorylated tau protein pathology. CTE's neuropathology has been formally defined as a tauopathy characterized by a distinct perivascular accumulation of hyperphosphorylated tau in neurons and astrocytes within cerebral sulci. Although the mechanism that underlies the unforeseen emergence of CTE long after the occurrence of one or more closed head traumas is unknown, an explanation proposed by Albayram and associates is persuasive. They discovered TBI-induced neuronal production of the toxic compound cis P-tau, an abnormal and destructive isomer of the normal and benign trans P-tau, in mouse models of CTE. Cis P-tau produced a CTE-like syndrome via a process they termed cistauosis. Cistauosis can be blocked in laboratory animals by cis P-tau monoclonal antibody, which prevents later development of tau tangles, brain atrophy and virtual CTE. In a subsequent study, the same group found in human samples obtained post-TBI from a variety of causes, that cis P-tau is induced in cortical axons and cerebrospinal fluid and positively correlates with axonal injury and clinical outcome. Thus, cis P-tau appears to contribute to short-term and long-term sequelae after TBI, but may be subject to neutralization by cis-antibody treatment.

Risk of female sexual dysfunction following concussion in women of reproductive age

Objectives: Traumatic Brain Injury (TBI) has frequently been associated with changes in sexual functioning. The TBI and sexuality literature, however, has limited generalizability to concussed females, who often use the emergency department (ED) as their first line of care after head injury. Primary Objective: The primary objective of this study was to evaluate the impact of concussions on female sexual functioning. Secondary Objective: Secondarily, we evaluated if concussed women with sexual dysfunction also report more post-concussion symptoms (PCS) and/or mood changes. Research Design: This was a prospective cohort, with outcomes assessed at 6-10 weeks after ED enrollment. Methods and Procedures: Sexual dysfunction was defined as ≤ 45 on the Brain Injury Questionnaire on Sexuality (BIQS). The Rivermead Post-concussion Symptoms Questionnaire (RPQ) and the Hospital Anxiety and Depression Scale (HADS) assessed PCS and post-injury mood, respectively. Main Outcomes & Results: Eighty-nine eumenorrheic females (8-14 menstrual cycles/year) completed the study; 31(36%) had concussions, and 55(64%) were extremity injured. Concussed women had 70% increased risk of sexual dysfunction (adj.RR:1.70, 95% CI: 1.04,2.76; p = .03) versus extremity injured. Of clinical relevance, concussed women with sexual dysfunction also reported more PCS symptoms (adj.β = 5.5, 95% CI: -6.7,18.2; p = .37) and mood scores (adj.β = 8.0; 95% CI: -0.4, 16.4; p = .06). Conclusions: This study highlights the need for more research and interventions for one of the fastest growing subgroups within the TBI population.

Quantitative microglia analyses reveal diverse morphologic responses in the rat cortex after diffuse brain injury

Determining regions of altered brain physiology after diffuse brain injury is challenging. Microglia, brain immune cells with ramified and dynamically moving processes, constantly surveil the parenchyma for dysfunction which, when present, results in a changed morphology. Our purpose was to define the spatiotemporal changes in microglia morphology over 28 days following rat midline fluid percussion injury (mFPI) as a first step in exploiting microglia morphology to reflect altered brain physiology. Microglia morphology was quantified from histological sections using Image J skeleton and fractal analysis procedures at three time points and in three regions post-mFPI: impact site, primary somatosensory cortex barrel field (S1BF), and a remote region. Microglia ramification (process length/cell and endpoints/cell) decreased in the impact and S1BF but not the remote region (p < 0.05). Microglia complexity was decreased in the S1BF (p = 0.003) and increased in the remote region (p < 0.02). Rod-shaped microglia were present in the S1BF and had a 1.8:1.0 length:width ratio. An in-depth quantitative morphologic analysis revealed diverse and widespread changes to microglia morphology in the cortex post-mFPI. Due to their close link to neuronal function, changes in microglia morphology, summarized in this study, likely reflect altered physiology with diverse and widespread impact on neuronal and circuit function.