White matter hyperintensities increases with traumatic brain injury severity: associations to neuropsychological performance and fatigue

Traumatic brain injury, posttraumatic stress disorder, and vascular risk are independently associated with white matter aging in Vietnam-Era veterans

OBJECTIVE

Traumatic brain injury (TBI), mental health conditions (e.g., posttraumatic stress disorder [PTSD]), and vascular comorbidities (e.g., hypertension, diabetes) are highly prevalent in the Veteran population and may exacerbate age-related changes to cerebral white matter (WM). Our study examined (1) relationships between health conditions-TBI history, PTSD, and vascular risk-and cerebral WM micro- and macrostructure, and (2) associations between WM measures and cognition.

METHOD

We analyzed diffusion tensor images from 183 older male Veterans (mean age = 69.18; SD = 3.61) with (n = 95) and without (n = 88) a history of TBI using tractography. Generalized linear models examined associations between health conditions and diffusion metrics. Total WM hyperintensity (WMH) volume was calculated from fluid-attenuated inversion recovery images. Robust regression examined associations between health conditions and WMH volume. Finally, elastic net regularized regression examined associations between WM measures and cognitive performance.

RESULTS

Veterans with and without TBI did not differ in severity of PTSD or vascular risk (p's >0.05). TBI history, PTSD, and vascular risk were independently associated with poorer WM microstructural organization (p's <0.5, corrected), however the effects of vascular risk were more numerous and widespread. Vascular risk was positively associated with WMH volume (p = 0.004, β=0.200, R2 = 0.034). Higher WMH volume predicted poorer processing speed (R2 = 0.052).

CONCLUSIONS

Relative to TBI history and PTSD, vascular risk may be more robustly associated with WM micro- and macrostructure. Furthermore, greater WMH burden is associated with poorer processing speed. Our study supports the importance of vascular health interventions in mitigating negative brain aging outcomes in Veterans.

What traditional neuropsychological assessment got wrong about mild traumatic brain injury. II: limitations in test development, research design, statistical and psychometric issues

PRIMARY OBJECTIVE

This is Part II of a four-part opinion review on traditional neuropsychological assessment methods and findings associated with mild traumatic brain injury (mTBI). This Part II review focuses on historical, psychometric and statistical issues involving traditional neuropsychological methods that have been used in neuropsychological outcome studies of mTBI, but demonstrates the critical limitations of traditional methods.

RESEARCH DESIGN

This is an opinion review.

METHODS AND PROCEDURES

Traditional neuropsychological tests are dated and lack specificity in evaluating such a heterogenous and complex injury as occurs with mTBI.

MAIN OUTCOME AND RESULTS

In this review, we demonstrate traditional neuropsychological methods were never developed as standalone measures for detecting subtle changes in neurocognitive or neurobehavioral functioning and likewise, never designed to address the multifaceted issues related to underlying mTBI neuropathology symptom burden from having sustained a concussive brain injury.

CONCLUSIONS

For neuropsychological assessment to continue to contribute to clinical practice and outcome literature involving mTBI, major innovative changes are needed that will likely require technological advances of novel assessment techniques more specifically directed to evaluating the mTBI patient. These will be discussed in Part IV.

White Matter Hyperintensities and Mild TBI in Post-9/11 Veterans and Service Members

INTRODUCTION

The neurobehavioral significance of white matter hyperintensities (WMHs) seen on magnetic resonance imaging after traumatic brain injury (TBI) remains unclear, especially in Veterans and Service Members with a history of mild TBI (mTBI). In this study, we investigate the relation between WMH, mTBI, age, and cognitive performance in a large multisite cohort from the Long-term Impact of Military-relevant Brain Injury Consortium-Chronic Effects of Neurotrauma Consortium.

MATERIALS AND METHODS

The neuroimaging and neurobehavioral assessments for 1,011 combat-exposed, post-9/11 Veterans and Service Members (age range 22-69 years), including those with a history of at least 1 mTBI (n = 813; median postinjury interval of 8 years) or negative mTBI history (n = 198), were examined.

RESULTS

White matter hyperintensities were present in both mTBI and comparison groups at similar rates (39% and 37%, respectively). There was an age-by-diagnostic group interaction, such that older Veterans and Service Members with a history of mTBI demonstrated a significant increase in the number of WMHs present compared to those without a history of mTBI. Additional associations between an increase in the number of WMHs and service-connected disability, insulin-like growth factor-1 levels, and worse performance on tests of episodic memory and executive functioning-processing speed were found.

CONCLUSIONS

Subtle but important clinical relationships are identified when larger samples of mTBI participants are used to examine the relationship between history of head injury and radiological findings. Future studies should use follow-up magnetic resonance imaging and longitudinal neurobehavioral assessments to evaluate the long-term implications of WMHs following mTBI.

Prior football or rugby exposure and white matter signal abnormalities in professional male mixed martial arts fighters

BACKGROUND

White matter signal abnormalities have been associated with traumatic brain injury (TBI) and repetitive head impacts (RHI) in contact sports (e.g. American football, rugby). However, previous studies of mixed martial arts (MMA) fighters from the Professional Fighters Brain Health Study have not found greater white matter signal abnormalities in fighters versus controls.

OBJECTIVE

This study aims to explore the varying white matter effects of football/rugby and MMA by analyzing how football/rugby history in mixed martial arts fighters may relate to white matter signal abnormalities, helping to further our understanding of sport-specific brain health risks.

METHODS

Baseline visits for 90 active, professional, male mixed martial arts fighters and 27 unexposed male controls were cross-sectionally analyzed. Wilcoxon and Kruskal-Wallis tests compared demographics and white matter signal abnormalities, and multivariable regression models examined the associations between football/rugby history and white matter signal abnormality burden in fighters, adjusting for age, education, race, fights, MRI scanner, and supratentorial volume.

RESULTS

37/90 fighters had football/rugby history (mean: 4 years; range: 1-12 years). White matter signal abnormalities were significantly greater in fighters with football/rugby history compared to fighters without football/rugby history (Wilcoxon, p = 0.0190). Football/rugby history was significantly associated with white matter signal abnormality burden >75th percentile (OR: 12, CI: 3.3-61, p < 0.001) and >50th percentile (OR: 3.2, CI: 1.2-9.4, p = 0.024) in fighters. Years of football/rugby were also significantly associated with white matter signal abnormalities.

CONCLUSION

Our findings expand on previous literature by demonstrating a significant relationship between white matter signal abnormalities (WMSAs) and football/rugby history but not MMA. Furthermore, our study suggests an added risk for WMSAs in MMA fighters with a history of football/rugby. Future research should further evaluate WMSAs in contact sports, helping to inform athletes, regulatory bodies, and healthcare providers of the potential brain health risks of contact sports.

The Effects of Early Life History of TBI on the Progression of Normal Brain Aging with Implications for Increased Dementia Risk

There is increasing interest in the risk conferred on neurological health by a traumatic brain injury (TBI) and how that influences the lifespan trajectory of brain aging. This chapter explores the importance of this issue, population, and methodological considerations, including injury documentation and outcome assessment. We then explore some of the findings in the neuroimaging and neuropsychological research literature examining the interaction between an earlier life history of TBI and the normal aging process. Finally, we consider the limitations of our current knowledge and where the field needs to go in the future.

An Understated Comorbidity: The Impact of Homelessness on Traumatic Brain Injury

Traumatic brain injury (TBI), a neurovascular injury caused by external force, is a common diagnosis among veterans and those experiencing homelessness (HL). There is a significant overlap in the veteran and homeless population, possibly accounting for the two to seven times greater incidence of TBI among those experiencing HL than the general population. Despite these statistics, individuals experiencing HL are often underdiagnosed and ineffectively treated for TBI. We introduced a novel model of HL. Over 5 weeks, adult Sprague-Dawley rats were randomly assigned to one of the following conditions: TBI only, HL only, TBI + HL, or control (n = 9 per group). To emulate HL, animals (2 animals per cage) were exposed to soiled beddings for 5 weeks. Subsequently, animals were introduced to TBI by using the moderate controlled cortical impact model, then underwent 4 consecutive days of behavioral testing (beam walk (BW), elevated body swing test (EBST), forelimb akinesia (FA), paw grasp (PG), Rotorod, and elevated T-maze). Nissl staining was performed to determine the peri-impact cell survival and the integrity of corpus callosum area. Motor function was significantly impaired by TBI, regardless of housing (beam walk or BW 85.0%, forelimb akinesia or FA 104.7%, and paw grasp or PG 100% greater deficit compared to control). Deficits were worsened by HL in TBI rats (BW 93.3%, FA 40.5%, and PG 50% greater deficit). Two-way ANOVA revealed BW (F(4, 160) = 31.69, p < 0.0001), FA (F(4, 160) = 13.71, p < 0.0001), PG (F(4, 160) = 3.873, p = 0.005), Rotorod (F(4, 160), p = 1.116), and EBST (F(4, 160) = 6.929, p < 0.0001) showed significant differences between groups. The Rotorod and EBST tests showed TBI-induced functional deficits when analyzed by day, but these deficits were not exacerbated by HL. TBI only and TBI + HL rats exhibited typical cortical impact damage (F(3,95) = 51.75, p < 0.0001) and peri-impact cell loss compared to control group (F(3,238) = 47.34, p < 0.0001). Most notably, TBI + HL rats showed significant alterations in WM area measured via the corpus callosum (F(3, 95) = 3.764, p = 0.0133). Worsened behavioral outcomes displayed by TBI + HL rats compared to TBI alone suggest HL contributes to TBI functional deficits. While an intact white matter, such as the corpus callosum, may lessen the consequent functional deficits associated with TBI by enhancing hemispheric communications, there are likely alternative cellular and molecular pathways mitigating TBI-associated inflammatory or oxidative stress responses. Here, we showed that the environmental condition of the patient, i.e., HL, participates in white matter integrity and behavioral outcomes, suggesting its key role in the disease diagnosis to aptly treat TBI patients.

Altered morphological connectivity mediated white matter hyperintensity-related cognitive impairment

White matter hyperintensities (WMH) are widely observed in older adults and are closely associated with cognitive impairment. However, the underlying neuroimaging mechanisms of WMH-related cognitive dysfunction remain unknown. This study recruited 61 WMH individuals with mild cognitive impairment (WMH-MCI, n = 61), 48 WMH individuals with normal cognition (WMH-NC, n = 48) and 57 healthy control (HC, n = 57) in the final analyses. We constructed morphological networks by applying the Kullback-Leibler divergence to estimate interregional similarity in the distributions of regional gray matter volume. Based on morphological networks, graph theory was applied to explore topological properties, and their relationship to WMH-related cognitive impairment was assessed. There were no differences in small-worldness, global efficiency and local efficiency. The nodal local efficiency, degree centrality and betweenness centrality were altered mainly in the limbic network (LN) and default mode network (DMN). The rich-club analysis revealed that WMH-MCI subjects showed lower average strength of the feeder and local connections than HC (feeder connections: P = 0.034; local connections: P = 0.042). Altered morphological connectivity mediated the relationship between WMH and cognition, including language (total indirect effect: -0.010; 95 % CI: -0.024, -0.002) and executive (total indirect effect: -0.010; 95 % CI: -0.028, -0.002) function. The altered topological organization of morphological networks was mainly located in the DMN and LN and was associated with WMH-related cognitive impairment. The rich-club connection was relatively preserved, while the feeder and local connections declined. The results suggest that single-subject morphological networks may capture neurological dysfunction due to WMH and could be applied to the early imaging diagnostic protocol for WMH-related cognitive impairment.

Military-related mild traumatic brain injury: clinical characteristics, advanced neuroimaging, and molecular mechanisms

Mild traumatic brain injury (mTBI) is a significant health burden among military service members. Although mTBI was once considered relatively benign compared to more severe TBIs, a growing body of evidence has demonstrated the devastating neurological consequences of mTBI, including chronic post-concussion symptoms and deficits in cognition, memory, sleep, vision, and hearing. The discovery of reliable biomarkers for mTBI has been challenging due to under-reporting and heterogeneity of military-related mTBI, unpredictability of pathological changes, and delay of post-injury clinical evaluations. Moreover, compared to more severe TBI, mTBI is especially difficult to diagnose due to the lack of overt clinical neuroimaging findings. Yet, advanced neuroimaging techniques using magnetic resonance imaging (MRI) hold promise in detecting microstructural aberrations following mTBI. Using different pulse sequences, MRI enables the evaluation of different tissue characteristics without risks associated with ionizing radiation inherent to other imaging modalities, such as X-ray-based studies or computerized tomography (CT). Accordingly, considering the high morbidity of mTBI in military populations, debilitating post-injury symptoms, and lack of robust neuroimaging biomarkers, this review (1) summarizes the nature and mechanisms of mTBI in military settings, (2) describes clinical characteristics of military-related mTBI and associated comorbidities, such as post-traumatic stress disorder (PTSD), (3) highlights advanced neuroimaging techniques used to study mTBI and the molecular mechanisms that can be inferred, and (4) discusses emerging frontiers in advanced neuroimaging for mTBI. We encourage multi-modal approaches combining neuropsychiatric, blood-based, and genetic data as well as the discovery and employment of new imaging techniques with big data analytics that enable accurate detection of post-injury pathologic aberrations related to tissue microstructure, glymphatic function, and neurodegeneration. Ultimately, this review provides a foundational overview of military-related mTBI and advanced neuroimaging techniques that merit further study for mTBI diagnosis, prognosis, and treatment monitoring.

Brain glucose metabolism and gray matter volume in retired professional soccer players: a cross-sectional [18F]FDG-PET/MRI study

BACKGROUND

 Professional soccer athletes are exposed to repetitive head impacts and are at risk of developing chronic traumatic encephalopathy.

OBJECTIVE

 To evaluate regional brain glucose metabolism (rBGM) and gray matter (GM) volume in retired soccer players (RSPs).

METHODS

 Male RSPs and age and sex-matched controls prospectively enrolled between 2017 and 2019 underwent neurological and neuropsychological evaluations, brain MRI and [18F]FDG-PET in a 3.0-Tesla PET/MRI scanner. Visual analysis was performed by a blinded neuroradiologist and a blinded nuclear physician. Regional brain glucose metabolism and GM volume were assessed using SPM8 software. Groups were compared using appropriate statistical tests available at SPM8 and R.

RESULTS

 Nineteen RSPs (median [IQR]: 62 [50-64.5] years old) and 20 controls (60 [48-73] years old) were included. Retired soccer players performed worse on mini-mental state examination, digit span, clock drawing, phonemic and semantic verbal fluency tests, and had reduced rBGM in the left temporal pole (pFDR = 0.008) and the anterior left middle temporal gyrus (pFDR = 0.043). Semantic verbal fluency correlated with rBGM in the right hippocampus, left temporal pole, and posterior left middle temporal gyrus (p ≤ 0.042). Gray matter volume reduction was observed in similar anatomic regions but was less extensive and did not survive correction for multiple comparisons (pFDR ≥ 0.085). Individual [18F]FDG-PET visual analysis revealed seven RSPs with overt hypometabolism in the medial and lateral temporal lobes, frontal lobes, and temporoparietal regions. Retired soccer players had a higher prevalence of septum pellucidum abnormalities on MRI.

CONCLUSION

 Retired soccer players had reduced rBGM and GM volume in the temporal lobes and septum pellucidum abnormalities, findings possibly related to repetitive head impacts.

How Traumatic Brain Injury History Relates to Brain Health MRI Markers and Dementia Risk: Findings from the 3C Dijon Cohort

BACKGROUND

The long-term effects of traumatic brain injury (TBI) with loss of consciousness (LOC) on magnetic resonance imaging (MRI) markers of brain health and on dementia risk are still debated.

OBJECTIVE

To investigate the associations of history of TBI with LOC with incident dementia and neuroimaging markers of brain structure and small vessel disease lesions.

METHODS

The analytical sample consisted in 4,144 participants aged 65 and older who were dementia-free at baseline from the Three City -Dijon study. History of TBI with LOC was self-reported at baseline. Clinical Dementia was assessed every two to three years, up to 12 years of follow-up. A subsample of 1,675 participants <80 years old underwent a brain MRI at baseline. We investigated the associations between history of TBI with LOC and 1) incident all cause and Alzheimer's disease (AD) dementia using illness-death models, and 2) neuroimaging markers at baseline.

RESULTS

At baseline, 8.3% of the participants reported a history of TBI with LOC. In fully-adjusted models, participants with a history of TBI with LOC had no statistically significant differences in dementia risk (HR = 0.90, 95% CI = 0.60-1.36) or AD risk (HR = 1.03, 95% CI = 0.69-1.52), compared to participants without TBI history. History of TBI with LOC was associated with lower white matter volume (β= -4.58, p = 0.048), but not with other brain volumes, white matter hyperintensities volume, nor covert brain infarct.

CONCLUSION

This study did not find evidence of an association between history of TBI with LOC and dementia or AD dementia risks over 12-year follow-up, brain atrophy, or markers of small vessel disease.

Cognitive-Linguistic outcome in moderate to severe diffuse axonal injury and association with fatigue

PURPOSE

Individuals with traumatic brain injury (TBI) often have persistent cognitive-linguistic deficits that negatively influence their life. Our objective was to examine the cognitive-linguistic outcome in individuals with moderate to severe diffuse axonal injury (DAI) with a novel test battery. As fatigue is a common symptom affecting the lives of individuals with DAI, we also wanted to assess whether the self-reported fatigue was associated with cognitive-linguistic abilities.

METHODS

Selected cognitive-linguistic subtests of the Finnish KAT test and The Mental Fatigue Scale (MFS) were applied to 48 adults with moderate to severe DAI and 27 healthy controls. The majority of the participants with DAI were in the chronic stage. The groups were compared using ANCOVA. Linear regressions were used to analyze the association between MFS and cognitive-linguistic outcomes.

RESULTS

The participants with DAI had significantly poorer scores than the controls in most cognitive-linguistic variables and reported significantly more fatigue. Two of the four cognitive-linguistic composite variables were associated with the degree of self-reported fatigue.

CONCLUSIONS

Cognitive-linguistic deficits are common in individuals with moderate to severe DAI, and The Finnish KAT test is a valuable tool to detect those. Fatigue was associated with linguistic working memory and language production.

Brain Injury and Mental Health Among the Victims of Intimate Partner Violence: A Case-Series Exploratory Study

Intimate partner violence (IPV) survivors frequently report face, head, and neck as their injury site. Many mild traumatic brain injuries (TBIs) are undiagnosed or underreported among IPV survivors while these injuries may be linked to changes in brain function or pathology. TBI sustained due to IPV often occurs over time and ranges in severity. The aim of this case-series study was to explore risk factors, symptoms, and brain changes unique to survivors of intimate partner violence with suspicion of TBI. This case-series exploratory study examines the potential relationships among IPV, mental health issues, and TBI. Participants of this study included six women: 3 women with a history of IPV without any experience of concussive blunt force to the head, and 3 women with a history of IPV with concussive head trauma. Participants completed 7T MRI of the brain, self-report psychological questionnaires regarding their mental health, relationships, and IPV, and the Structured Clinical Interview. MRI scans were analyzed for cerebral hemorrhage, white matter disturbance, and cortical thinning. Results indicated significant differences in resting-state connectivity among survivors of partner violence as well as differences in relationship dynamics and mental health symptoms. White matter hyperintensities are also observed among the survivors. Developing guidelines and recommendations for TBI-risk screening, referrals, and appropriate service provision is crucial for the effective treatment of TBI-associated IPV. Early and accurate characterization of TBI in survivors of IPV may relieve certain neuropsychological consequences.

Neuroradiologic Evaluation of MRI in High-Contact Sports

Background and Purpose: Athletes participating in high-contact sports experience repeated head trauma. Anatomical findings, such as a cavum septum pellucidum, prominent CSF spaces, and hippocampal volume reductions, have been observed in cases of mild traumatic brain injury. The extent to which these neuroanatomical findings are associated with high-contact sports is unknown. The purpose of this study was to determine whether there are subtle neuroanatomic differences between athletes participating in high-contact sports compared to low-contact athletic controls.

Materials and Methods: We performed longitudinal structural brain MRI scans in 63 football (high-contact) and 34 volleyball (low-contact control) male collegiate athletes with up to 4 years of follow-up, evaluating a total of 315 MRI scans. Board-certified neuroradiologists performed semi-quantitative visual analysis of neuroanatomic findings, including: cavum septum pellucidum type and size, extent of perivascular spaces, prominence of CSF spaces, white matter hyperintensities, arterial spin labeling perfusion asymmetries, fractional anisotropy holes, and hippocampal size.

Results: At baseline, cavum septum pellucidum length was greater in football compared to volleyball controls (p = 0.02). All other comparisons were statistically equivalent after multiple comparison correction. Within football at baseline, the following trends that did not survive multiple comparison correction were observed: more years of prior football exposure exhibited a trend toward more perivascular spaces (p = 0.03 uncorrected), and lower baseline Standardized Concussion Assessment Tool scores toward more perivascular spaces (p = 0.02 uncorrected) and a smaller right hippocampal size (p = 0.02 uncorrected).

Conclusion: Head impacts in high-contact sport (football) athletes may be associated with increased cavum septum pellucidum length compared to low-contact sport (volleyball) athletic controls. Other investigated neuroradiology metrics were generally equivalent between sports.

White Matter Hyperintensities Are Not Related to Symptomatology or Cognitive Functioning in Service Members with a Remote History of Traumatic Brain Injury

This study aimed to determine whether magnetic resonance imaging (MRI) white matter hyperintensities (WMHs) are associated with symptom reporting and/or cognitive performance in 1202 active-duty service members with prior single or multiple mild traumatic brain injury (mTBI). Patients with mTBI evaluated at the National Intrepid Center of Excellence (NICoE) at Walter Reed National Military Medical Center (WRNMMC) were divided into those with (n = 632) and without (n = 570) WMHs. The groups were compared on several self-report scales including the Neurobehavioral Symptom Inventory (NSI), Post-Traumatic Stress Disorder (PTSD) Checklist-Civilian Version (PCL-C), Satisfaction with Life Scale (SWLS), and Short Form-36 Health Survey (SF-36). They were also compared on several neuropsychological measures, including tests of attention, working memory, learning and memory, executive functioning, and psychomotor functioning. After correction for multiple comparisons, there were no significant differences between the two groups on any self-reported symptom scale or cognitive test. When comparing a subgroup with the highest (20+) WMH burden (n = 60) with those with no WMHs (n = 60; matched on age, education, sex, race, rank, and TBI number), only SF-36 Health Change significantly differed between the subgroups; the multiple WMH subgroup reported worsening health over the past year (t[53] = 3.52, p = 0.001, d = 0.67) compared with the no WMH subgroup. These findings build on prior research suggesting total WMHs are not associated with significant changes in self-reported symptoms or cognitive performance in patients with a remote history of mTBI. As such, clinicians are encouraged to use caution when reporting such imaging findings.

Mental Fatigue after Mild Traumatic Brain Injury in Relation to Cognitive Tests and Brain Imaging Methods

Most people recover within months after a mild traumatic brain injury (TBI) or concussion, but some will suffer from long-term fatigue with a reduced quality of life and the inability to maintain their employment status or education. For many people, mental fatigue is one of the most distressing and long-lasting symptoms following an mTBI. No efficient treatment options can be offered. The best method for measuring fatigue today is with fatigue self-assessment scales, there being no objective clinical tests available for mental fatigue. The aim here is to provide a narrative review and identify fatigue in relation to cognitive tests and brain imaging methods. Suggestions for future research are presented.