Associations of Nightmares and Sleep Disturbance With Neurobehavioral Symptoms Postconcussion.

OBJECTIVE: This study investigates the association of nightmares beyond general sleep disturbance on neurobehavioral symptoms in adults with mild traumatic brain injury (mTBI). DESIGN: Secondary analysis of a concussion cohort study. PARTICIPANTS: One hundred and eleven adults older than 20 years with mTBI were recruited from a specialized concussion treatment center. MAIN MEASURES: Behavioral Assessment Screening Tool, Pittsburgh Sleep Quality Index, and self-report of nightmare frequency in the past 2 weeks. RESULTS: Among adults with mTBI, nightmares accounted for the greatest amount of variability in negative affect (ß = .362, P < .001), anxiety (ß = .332, P < .001), and impulsivity (ß = .270, P < .001) after adjusting for age and sex. Overall sleep disturbance had the strongest association with depression (ß = .493, P < .001), fatigue (ß = .449, P < .001), self-reported executive dysfunction (ß = .376, P < .001), and overall burden from concussive symptoms (ß = .477, P < .001). CONCLUSIONS: Nightmares and sleep disturbance are differentially associated with variance in neurobehavioral symptoms. Nightmares were independently associated with neurobehavioral symptoms representing an excess of normal functioning (eg, anxiety, impulsivity), while general sleep disturbance was associated with neurobehavioral symptoms representing functioning below normal levels (eg, depression, fatigue, self-reported executive dysfunction). Clinical and research implications are discussed.

Interaction of obesity and proteins associated with the NLRP3 inflammasome following mild traumatic brain injury.

The NOD-like receptor pyrin domain-containing protein 3 (NLRP3) inflammasome has been associated with worse outcomes from severe traumatic brain injury (TBI). The NLRP3 inflammasome is also strongly associated with other pro-inflammatory conditions, such as obesity. Little is known about the potential effect of mild TBI (mTBI) on the NLRP3 inflammasome and the extent to which modifying factors, such as obesity, may augment the inflammatory response to mTBI. The purpose of this study was to evaluate the association of NLRP3 inflammasome proteins with obese body mass index (BMI ≥ 30) within 24 h of mTBI after presenting to a level 1 trauma center emergency department. This is a secondary analysis of prospectively enrolled patients with mTBI who presented to the emergency department of one U.S. Level 1 trauma center from 2013 to 2018 (n = 243). A series of regression models were built to evaluate the association of NLRP3 proteins obtained from blood plasma within 24 h of injury and BMI as well as the potential interaction effect of higher BMI with NLRP3 proteins (n = 243). A logistic regression model revealed a significant association between IL-18 (p < 0.001) in mTBI patients with obese BMI compared to mTBI patients with non-obese BMI (< 30). Moderation analyses revealed statistically significant interaction effects between apoptotic speck-like protein (ASC), caspase-1, IL-18, IL-1ß and obese BMI which worsened symptom burden, quality of life, and physical function at 2 weeks and 6 months post-injury. Higher acute concentrations of IL-1ß in the overall cohort predicted higher symptoms at 6-months and worse physical function at 2-weeks and 6-months. Higher acute concentrations of IL-18 in the overall cohort predicted worse physical function at 6-months. In this single center mTBI cohort, obese BMI interacted with higher acute concentrations of NLRP3 inflammasome proteins and worsened short- and long-term clinical outcomes.

A Proposed Mechanism for Visual Vertigo: Post-Concussion Patients Have Higher Gain From Visual Input Into Subcortical Gaze Stabilization.

Purpose: Post-concussion syndrome (PCS) is commonly associated with dizziness and visual motion sensitivity. This case-control study set out to explore altered motion processing in PCS by measuring gaze stabilization as a reflection of the capacity of the brain to integrate motion, and it aimed to uncover mechanisms of injury where invasive subcortical recordings are not feasible. Methods: A total of 554 eye movements were analyzed in 10 PCS patients and nine healthy controls across 171 trials. Optokinetic and vestibulo-ocular reflexes were recorded using a head-mounted eye tracker while participants were exposed to visual, vestibular, and visuo-vestibular motion stimulations in the roll plane. Torsional and vergence eye movements were analyzed in terms of slow-phase velocities, gain, nystagmus frequency, and sensory-specific contributions toward gaze stabilization. Results: Participants expressed eye-movement responses consistent with expected gaze stabilization; slow phases were fastest for visuo-vestibular trials and slowest for visual stimulations (P < 0.001) and increased with stimulus acceleration (P < 0.001). Concussed patients demonstrated increased gain from visual input to gaze stabilization (P = 0.005), faster slow phases (P = 0.013), earlier nystagmus beats (P = 0.003), and higher relative visual influence over the gaze-stabilizing response (P = 0.001), presenting robust effect sizes despite the limited population size. Conclusions: The enhanced neural responsiveness to visual motion in PCS, combined with semi-intact visuo-vestibular integration, presented a subcortical hierarchy for altered gaze stabilization. Drawing on comparable animal trials, findings suggest that concussed patients may suffer from diffuse injuries to inhibiting pathways for optokinetic information, likely early in the visuo-vestibular hierarchy of sensorimotor integration. These findings offer context for common but elusive symptoms, presenting a neurological explanation for motion sensitivity and visual vertigo in PCS.

Olfactory function after mild traumatic brain injury in children-a longitudinal case control study.

The prevalence of posttraumatic olfactory dysfunction in children after mild traumatic brain injury ranges from 3 to 58%, with potential factors influencing this variation, including traumatic brain injury severity and assessment methods. This prospective longitudinal study examines the association between mild traumatic brain injury and olfactory dysfunction in children. Seventy-five pediatric patients with mild traumatic brain injury and an age-matched healthy control group were enrolled. Olfactory function was assessed using the Sniffin' Sticks battery, which focuses on olfactory threshold and odor identification. The study found that children with mild traumatic brain injury had impaired olfactory function compared with healthy controls, particularly in olfactory threshold scores. The prevalence of olfactory dysfunction in the patient group was 33% and persisted for 1 yr. No significant association was found between traumatic brain injury symptoms (e.g. amnesia, loss of consciousness) and olfactory dysfunction. The study highlights the importance of assessing olfactory function in children after mild traumatic brain injury, given its potential impact on daily life. Although most olfactory dysfunction appears transient, long-term follow-up is essential to fully understand the recovery process. The findings add valuable insights to the limited literature on this topic and urge the inclusion of olfactory assessments in the management of pediatric mild traumatic brain injury.

Posttraumatic Headache.

OBJECTIVE: This article provides an overview of the epidemiology, diagnosis, clinical presentation, pathophysiology, prognosis, and treatment of posttraumatic headache attributed to mild traumatic brain injury (mTBI). LATEST DEVELOPMENTS: The International Classification of Headache Disorders, Third Edition requires that posttraumatic headache begin within 7 days of the inciting trauma. Although posttraumatic headache characteristics and associated symptoms vary, most commonly there is substantial overlap with symptoms of migraine or tension-type headache. New insights into posttraumatic headache pathophysiology suggest roles for neuroinflammation, altered pain processing and modulation, and changes in brain structure and function. Although the majority of posttraumatic headache resolves during the acute phase, about one-third of individuals have posttraumatic headache that persists for at least several months. Additional work is needed to identify predictors and early markers of posttraumatic headache persistence, but several potential predictors have been identified such as having migraine prior to the mTBI, the total number of TBIs ever experienced, and the severity of initial symptoms following the mTBI. Few data are available regarding posttraumatic headache treatment; studies investigating different treatments and the optimal timing for initiating posttraumatic headache treatment are needed. ESSENTIAL POINTS: Posttraumatic headache begins within 7 days of the causative injury. The characteristics of posttraumatic headache most commonly resemble those of migraine or tension-type headache. Posttraumatic headache persists for 3 months or longer in about one-third of individuals. Additional studies investigating posttraumatic headache treatment are needed.

Chronic immunosuppression across 12 months and high ability of acute and subacute CNS-injury biomarker concentrations to identify individuals with complicated mTBI on acute CT and MRI.

BACKGROUND: Identifying individuals with intracranial injuries following mild traumatic brain injury (mTBI), i.e. complicated mTBI cases, is important for follow-up and prognostication. The main aims of our study were (1) to assess the temporal evolution of blood biomarkers of CNS injury and inflammation in individuals with complicated mTBI determined on computer tomography (CT) and magnetic resonance imaging (MRI); (2) to assess the corresponding discriminability of both single- and multi-biomarker panels, from acute to chronic phases after injury. METHODS: Patients with mTBI (n = 207), defined as Glasgow Coma Scale score between 13 and 15, loss of consciousness < 30 min and post-traumatic amnesia < 24 h, were included. Complicated mTBI - i.e., presence of any traumatic intracranial injury on neuroimaging - was present in 8% (n = 16) on CT (CT+) and 12% (n = 25) on MRI (MRI+). Blood biomarkers were sampled at four timepoints following injury: admission (within 72 h), 2 weeks (± 3 days), 3 months (± 2 weeks) and 12 months (± 1 month). CNS biomarkers included were glial fibrillary acidic protein (GFAP), neurofilament light (NFL) and tau, along with 12 inflammation markers. RESULTS: The most discriminative single biomarkers of traumatic intracranial injury were GFAP at admission (CT+: AUC = 0.78; MRI+: AUC = 0.82), and NFL at 2 weeks (CT+: AUC = 0.81; MRI+: AUC = 0.89) and 3 months (MRI+: AUC = 0.86). MIP-1ß and IP-10 concentrations were significantly lower across follow-up period in individuals who were CT+ and MRI+. Eotaxin and IL-9 were significantly lower in individuals who were MRI+ only. FGF-basic concentrations increased over time in MRI- individuals and were significantly higher than MRI+ individuals at 3 and 12 months. Multi-biomarker panels improved discriminability over single biomarkers at all timepoints (AUCs > 0.85 for admission and 2-week models classifying CT+ and AUC ≈ 0.90 for admission, 2-week and 3-month models classifying MRI+). CONCLUSIONS: The CNS biomarkers GFAP and NFL were useful single diagnostic biomarkers of complicated mTBI, especially in acute and subacute phases after mTBI. Several inflammation markers were suppressed in patients with complicated versus uncomplicated mTBI and remained so even after 12 months. Multi-biomarker panels improved diagnostic accuracy at all timepoints, though at acute and 2-week timepoints, the single biomarkers GFAP and NFL, respectively, displayed similar accuracy compared to multi-biomarker panels.

The effect of repeated concussions on clinical and neurocognitive symptom severity in different contact sports.

INTRODUCTION: The potential consequences of repeated concussions in sport are well documented. However, it remains unclear whether the cumulative impact of sports-related concussions differs between different contact sports. Therefore, the aim of the current study was to investigate the cumulative effects of sports-related concussions on clinical and neurocognitive health in different contact sports. MATERIALS AND METHODS: In a prospective multicenter study, we examined 507 (74 females) active professional athletes between 18 and 40 years of age from five different contact sports (soccer, handball, American football, basketball, and ice hockey). Data collection involved concussion history, clinical symptom evaluation, neurocognitive assessment, and the collection of other sports-related information. Composite scores were built for clinical symptoms (such as neck pain and balance disturbances) and for neurocognitive symptoms (such as memory and attention impairments). RESULTS: Athletes having suffered 3+ concussions in the past showed disproportionally higher clinical symptom severity than athletes with less than three concussions across all sports. The level of clinical symptom burden in athletes with 3+ concussions indicated mild impairment. The number of past concussions did not affect neurocognitive performance. DISCUSSION: Repeated sports-related concussions appear to have a cumulative impact on clinical-but not cognitive-symptom severity. Although clinical symptom burden in athletes with 3+ concussions in the past was not alarmingly high yet in our sample, increased caution should be advised at this point. Despite few exceptions, results are similar for different contact sports, suggesting a similar multidisciplinary concussion management across all types of sport.

The Postconcussion Syndrome and Posttraumatic Headaches in Civilians, Soldiers, and Athletes.

Posttraumatic headaches are one of the most common and controversial secondary headache types. After a mild traumatic brain, an estimated 11% to 82% of people develop a postconcussion syndrome, which has been controversial for more than 160 years. Headache is estimated as present in 30% to 90% of patients after a mild head injury. Most headaches are tension-type-like or migraine-like. Headaches in civilians, soldiers, athletes, and postcraniotomy are reviewed. The treatments are the same as for the primary headaches. Persistent posttraumatic headaches can continue for many years.

Recovery duration and concussion severity in sport- and non-sport-related concussion among Pac-12 collegiate athletes: a retrospective cohort study.

OBJECTIVES: To examine non-sport- and sport-related concussion severity, clinical care frequency and delayed reporting in relation to recovery duration among collegiate athletes. DESIGN: Retrospective cohort study. SETTING: Pac-12 varsity collegiate athletes. PARTICIPANTS: 461 collegiate male and female athletes PRIMARY AND SECONDARY OUTCOME MEASURES: The incidence of sport-related concussion (SRC) and non-sport-related concussion (NRC) were collected as well as times to recovery and return-to-play (RTP), symptom score and symptom severity and reported a loss of consciousness (LOC), retrograde amnesia (RGA) and post-traumatic amnesia (PTA) following concussion incidence. RESULTS: Among 461 concussions, 388 (84%) occurred within sport and 73 (16%) occurred outside of sport. NRC, on average, required 3.5 more days to become asymptomatic (HR: 0.73, 95%confidence interval: 0.56 to 0.96, p=0.02) and 7 more days to RTP (HR: 0.64, 95% confidence interval: 0.49 to 0.85, p<0.01) compared with SRC. NRC were associated with an increase of 1.83 (p=0.07) symptoms reported at the time of diagnosis, an increase of 6.95 (p=0.06) in symptom severity and a higher prevalence of reported LOC (22% NRC vs. 3% SRC, p<0.001), PTA (15% NRC vs. 5% SRC, p<0.01) and RGA (10% NRC vs. 4% SRC, p=0.06), compared with SRC. There was no significant difference in clinical care (p=0.28) or immediate reporting (p=0.35) between NRC and SRC. CONCLUSION: NRC were associated with greater severity and longer recovery duration when compared with SRC in a cohort of collegiate athletes.

Lower cognitive reserve is related to worse working memory performance in older adults after mTBI. An ERP study.

OBJECTIVE: Older adults (OA) after mild traumatic brain injury (mTBI) have a high risk of developing persistent post-injury cognitive impairments. Lower pre-morbid cognitive reserve (CR) is increasingly investigated as a risk factor for cognitive dysfunction in OA. However, how CR protects against effects of mTBI at the brain level remains largely understudied. METHODS: We examined 22 OA who sustained mTBI (mean 67.69 years, SD 5.11) in the sub-acute phase and 15 age- and CR-matched healthy OA (mean 68 years, SD 5.55) performing a three-level visual N-back task using electroencephalography. We calculated inverse efficiency scores of performance from accuracy and reaction times. Event-related potentials served as neurocognitive correlates of attentional (P2) and working memory (P3) processing. RESULTS: Overall, mTBI OA performed worse than healthy OA (p = 0.031). Lower CR generally decreased performance (p < 0.001). Furthermore, with increasing task difficulty, task performance was more affected by CR (p = 0.004). At the brain level, P2 amplitude was lower in mTBI OA than in healthy OA (p = 0.05). There was no clear effect of CR on P2 or P3 measures. CONCLUSION: As mTBI OA with lower CR performed worse on a working-memory task, lower CR may be a risk factor for worse recovery after mTBI in this group.

Relationship between severity of concussion's symptoms and functional performance in children.

INTRODUCTION: Concussion is a common brain injury that has significant effects on multiple functional domains in children. However, limited research exists on the relationship between concussion severity and functional performance in this population. This study aimed to examine the relationship between the severity of concussion symptoms and children's balance and functional performance. METHODS: This cross-sectional study recruited 23 children (9 males and 14 females; mean age 13.9 ± 2.2 years) with clinically diagnosed concussions from a tertiary balance center in 2016. Participants underwent clinical and functional evaluations by specialized physical therapists. Symptom severity was assessed using the Post-Concussion Symptom Scale (PCSS), while functional performance was measured using the Functional Gait Assessment (FGA). RESULTS: There was a trend suggesting a negative correlation between symptom severity (PCSS) and functional performance (FGA), indicating potentially better performance in individuals with milder symptoms. However, this trend was not significant (rs (21) = -.072, p = 0.744). Furthermore, no significant correlation was found between FGA scores and the severity of individual symptoms. CONCLUSION: The findings suggest that concussion symptom severity may not be directly related to functional performance in children. Therefore, it is crucial to incorporate functional performance measures alongside symptom assessment for comprehensive concussion management.

Concussion symptom presentation and clinical recovery among pediatric athletes: comparing concussions sustained during school and summer months.

OBJECTIVE: We examined post-concussion symptom presentation, exercise, and sleep among pediatric athletes who sustained concussion during the school year vs. summer months. METHODS: We evaluated athletes 6-18 years old within 21-days of concussion. They reported symptoms (Health and Behavior Inventory), with cognitive/somatic domain sub-scores calculated, and indicated if they had exercised or experienced sleep problems since injury. We grouped patients by injury season: summer months (June-August) vs. school year (September-May). RESULTS: 350 patients (14.4 ± 2.4 years old; 37% female; initial visit 8.8 ± 5.3 days post-concussion) were seen for care: 24% sustained a concussion during summer months, 76% during the school year. Lower cognitive (median = 7 [IQR = 1, 15] vs. 9.5 [4, 17]; p = 0.01), but not somatic (7 [2.5, 11] vs. 8 [4, 13]; p = 0.06), HBI scores were observed for patients injured during the summer. Groups were similar in proportion exercising (16% vs 17%) and endorsing sleep problems (29% vs 31%). After adjustments, sustaining a concussion during the summer predicted total (ß=-3.43; 95%CI = -6.50, -0.36; p = 0.029) and cognitive (ß = -2.29; 95%CI = -4.22, -0.36; p = 0.02), but not somatic (ß=-1.46; 95%CI = -2.84, -0.08; p = 0.04), symptom severity. CONCLUSION: Pediatric patients with concussion may present with greater cognitive symptoms during the school year, compared to summer months.

Postconcussive Symptoms After Early Childhood Concussion.

Importance: Research on postconcussive symptoms (PCS) following early childhood concussion has been hindered by a lack of measures suitable for this age group, resulting in a limited understanding of their evolution in young children. Objective: To document PCS in the first 3 months after early childhood concussion using a developmentally appropriate measure. Design, Setting, and Participants: This cohort study used data collected at 3 Canadian and 1 US urban pediatric emergency departments (EDs) and 8 Canadian daycares from December 2018 to December 2022 as part of the Kids' Outcomes and Long-Term Abilities (KOALA) project, a prospective, multicenter, longitudinal cohort study. Participants included children aged 6 to 72 months with early childhood concussion or orthopedic injury (OI) or uninjured children from the community to serve as controls. Data were analyzed from March 2023 to January 2024. Exposure: Concussion sustained between ages 6 and 72 months. Main Outcomes and Measures: Primary outcomes were cognitive, physical, behavioral and total PCS assessed prior to injury (retrospectively), acutely (within 48 hours), and at 10 days, 1 month, and 3 months after injury or recruitment through caregiver observations using the Report of Early Childhood Traumatic Injury Observations & Symptoms inventory. Group comparisons were analyzed using ordinal regression models. Results: The study included 303 children (mean [SD] age, 35.8 [20.2] months; 152 [50.2%] male). Of these, 174 children had a concussion (mean [SD] age, 33.3 [19.9] months), 60 children had an OI (mean [SD] age, 38.4 [19.8] months) and 69 children were uninjured controls (mean [SD] age, 39.7 [20.8] months). No meaningful differences were found between the concussion and comparison groups in retrospective preinjury PCS. Significant group differences were found for total PCS at the initial ED visit (concussion vs OI: odds ratio [OR], 4.33 [95% CI, 2.44-7.69]; concussion vs control: OR, 7.28 [95% CI, 3.80-13.93]), 10 days (concussion vs OI: OR, 4.44 [95% CI, 2.17-9.06]; concussion vs control: OR, 5.94 [95% CI, 3.22-10.94]), 1 month (concussion vs OI: OR, 2.70 [95% CI, 1.56-4.68]; concussion vs control: OR, 4.32 [95% CI, 2.36-7.92]), and 3 months (concussion vs OI: OR, 2.61 [95% CI, 1.30-5.25]; concussion vs control: OR, 2.40 [95% CI, 1.36-4.24]). Significant group differences were also found for domain-level scores (cognitive, physical, behavioral) at various time points. Conclusions and Relevance: In this early childhood cohort study, concussion was associated with more PCS than OIs or typical development up to 3 months after injury. Given the limited verbal and cognitive abilities typical of early childhood, using developmentally appropriate manifestations and behaviors is a valuable way of tracking PCS and could aid in concussion diagnosis in young children.

Prefrontal Cortex Activity During Gait in People With Persistent Symptoms After Concussion.

BACKGROUND: Concussions result in transient symptoms stemming from a cortical metabolic energy crisis. Though this metabolic energy crisis typically resolves in a month, symptoms can persist for years. The symptomatic period is associated with gait dysfunction, the cortical underpinnings of which are poorly understood. Quantifying prefrontal cortex (PFC) activity during gait may provide insight into post-concussion gait dysfunction. The purpose of this study was to explore the effects of persisting concussion symptoms on PFC activity during gait. We hypothesized that adults with persisting concussion symptoms would have greater PFC activity during gait than controls. Within the concussed group, we hypothesized that worse symptoms would relate to increased PFC activity during gait, and that increased PFC activity would relate to worse gait characteristics. METHODS: The Neurobehavior Symptom Inventory (NSI) characterized concussion symptoms. Functional near-infrared spectroscopy quantified PFC activity (relative concentration changes of oxygenated hemoglobin [HbO2]) in 14 people with a concussion and 25 controls. Gait was assessed using six inertial sensors in the concussion group. RESULTS: Average NSI total score was 26.4 (13.2). HbO2 was significantly higher (P = .007) for the concussed group (0.058 [0.108]) compared to the control group (-0.016 [0.057]). Within the concussion group, HbO2 correlated with NSI total symptom score (ρ = .62; P = .02), sagittal range of motion (r = .79; P = .001), and stride time variability (r = -.54; P = .046). CONCLUSION: These data suggest PFC activity relates to symptom severity and some gait characteristics in people with persistent concussion symptoms. Identifying the neurophysiological underpinnings to gait deficits post-concussion expands our knowledge of motor behavior deficits in people with persistent concussion symptoms.

Prevalence of fatigue and cognitive impairment after traumatic brain injury.

BACKGROUND: Following traumatic brain injury (TBI) some patients develop lingering comorbid symptoms of fatigue and cognitive impairment. The mild cognitive impairment self-reported by patients is often not detected with neurocognitive tests making it difficult to determine how common and severe these symptoms are in individuals with a history of TBI. This study was conducted to determine the relative prevalence of fatigue and cognitive impairment in individuals with a history of TBI. METHODS: The Fatigue and Altered Cognition Scale (FACs) digital questionnaire was used to assess self-reported fatigue and cognitive impairment. Adults aged 18-70 were digitally recruited for the online anonymous study. Eligible participants provided online consent, demographic data, information about lifetime TBI history, and completed the 20 item FACs questionnaire. RESULTS: A total of 519 qualifying participants completed the online digital study which included 204 participants with a history of TBI of varied cause and severity and 315 with no history of TBI. FACs Total Score was significantly higher in the TBI group (57.7 ± 22.2) compared to non-TBI (39.5 ± 23.9; p<0.0001) indicating more fatigue and cognitive impairment. When stratified by TBI severity, FACs score was significantly higher for all severity including mild (53.9 ± 21.9, p<0.0001), moderate (54.8 ± 24.4, p<0.0001), and severe (59.7 ± 20.9, p<0.0001) TBI. Correlation analysis indicated that more severe TBI was associated with greater symptom severity (p<0.0001, r = 0.3165). Ancillary analysis also suggested that FACs scores may be elevated in participants with prior COVID-19 infection but no history of TBI. CONCLUSIONS: Adults with a history of even mild TBI report significantly greater fatigue and cognitive impairment than those with no history of TBI, and symptoms are more profound with greater TBI severity.

Study protocol: Identifying transcriptional regulatory alterations of chronic effects of blast and disturbed sleep in United States Veterans.

Injury related to blast exposure dramatically rose during post-911 era military conflicts in Iraq and Afghanistan. Mild traumatic brain injury (mTBI) is among the most common injuries following blast, an exposure that may not result in a definitive physiologic marker (e.g., loss of consciousness). Recent research suggests that exposure to low level blasts and, more specifically repetitive blast exposure (RBE), which may be subconcussive in nature, may also impact long term physiologic and psychological outcomes, though findings have been mixed. For military personnel, blast-related injuries often occur in chaotic settings (e.g., combat), which create challenges in the immediate assessment of related-injuries, as well as acute and post-acute sequelae. As such, alternate means of identifying blast-related injuries are needed. Results from previous work suggest that epigenetic markers, such as DNA methylation, may provide a potential stable biomarker of cumulative blast exposure that can persist over time. However, more research regarding blast exposure and associations with short- and long-term sequelae is needed. Here we present the protocol for an observational study that will be completed in two phases: Phase 1 will address blast exposure among Active Duty Personnel and Phase 2 will focus on long term sequelae and biological signatures among Veterans who served in the recent conflicts and were exposed to repeated blast events as part of their military occupation. Phase 2 will be the focus of this paper. We hypothesize that Veterans will exhibit similar differentially methylated regions (DMRs) associated with changes in sleep and other psychological and physical metrics, as observed with Active Duty Personnel. Additional analyses will be conducted to compare DMRs between Phase 1 and 2 cohorts, as well as self-reported psychological and physical symptoms. This comparison between Service Members and Veterans will allow for exploration regarding the natural history of blast exposure in a quasi-longitudinal manner. Findings from this study are expected to provide additional evidence for repetitive blast-related physiologic changes associated with long-term neurobehavioral symptoms. It is expected that findings will provide foundational data for the development of effective interventions following RBE that could lead to improved long-term physical and psychological health.

Cognitive Impairment following Mild Traumatic Brain Injury (mTBI): A Review.

Background: Mild Traumatic Brain Injury (mTBI) has been increasingly recognized as a public health concern due to its prevalence and potential to induce long-term cognitive impairment. We aimed to consolidate this observation by focusing on findings of neuropsychological assessments, neuroimaging, risk factors, and potential strategies for intervention to prevent and treat mTBI-associated cognitive impairments. Methods: A thorough search of PubMed, PsycINFO, and Embase databases was performed for studies published until 2024. Studies focusing on cognitive impairment after mTBI, with neurocognitive assessment as a primary outcome, were included. Results: We found consistent evidence of cognitive deficits, such as memory and attention impairments, and affected executive functions following mTBI. Neuroimaging studies corroborate these findings, highlighting structural and functional changes in the brain. Several risk factors for developing cognitive impairment post-mTBI were identified, including age, gender, genetics, and pre-existing mental health conditions. The efficacy of interventions, including cognitive rehabilitation and pharmaceutical treatment, varied across studies. Conclusions: Mild TBI can lead to significant long-term cognitive impairments, impacting an individual's quality of life. Further research is necessary to validate and standardize cognitive assessment tools post-mTBI, to elucidate the underlying neural mechanisms, and to optimize therapeutic interventions.

Stressful life events are associated with self-reported fatigue and depressive symptoms in patients with mild traumatic brain injury.

OBJECTIVE: To examine the associations between recent stressful life events and self-reported fatigue and depressive symptoms in patients with mild traumatic brain injury. DESIGN: Observational cohort study. PARTICIPANTS: Patients (aged 18-68 years) with mild traumatic brain injury (n = 99) or lower extremity orthopaedic injury (n = 34). METHODS: Data on stressful life events and self-reported symptoms were collected 3 months post-injury. Stressful life events in the last 12 months were assessed as part of a structured interview using a checklist of 11 common life events, self-reported fatigue with Barrow Neurological Institute Fatigue Scale, and depressive symptoms with Beck Depression Inventory - Fast Screen. RESULTS: Median number of stressful life events was 1 (range 0-7) in the mild traumatic brain injury group and 1.5 (range 0-6) in the orthopaedic injury group. The groups did not differ significantly in terms of fatigue or depressive symptoms. In the mild traumatic brain injury group, the total number of recent stressful life events correlated significantly with self-reported fatigue (rs = 0.270, p = 0.007) and depressive symptoms (rs = 0.271, p = 0.007). CONCLUSION: Stressful life events are associated with self-reported fatigue and depressive symptoms in patients with mild traumatic brain injury. Clinicians should consider stressful life events when managing patients who experience these symptoms, as this may help identifying potential targets for intervention.

CSF ß-Amyloid and Tau Biomarker Changes in Veterans With Mild Traumatic Brain Injury.

BACKGROUND AND OBJECTIVES: Moderate-to-severe traumatic brain injuries (TBI) have been reported to increase the risk of Alzheimer disease (AD). Whether mild TBI (mTBI) in veterans confers a similar increased risk of AD is less known. This study investigated early AD changes using CSF biomarkers in veterans with blast mTBI. METHODS: This was a cross-sectional case-control study of veterans with mTBI and non-mTBI veterans and civilians from 2 study sources. Blast-mTBI veterans had at least 1 war zone blast or combined blast/impact mTBI meeting Veterans Affairs (VA) and Department of Defense (DoD) criteria for mTBI. Non-mTBI participants had no lifetime history of TBI. All participants underwent standardized clinical and neuropsychological assessments and lumbar puncture for collection of the CSF. CSF biomarkers were measured using MesoScale Discovery assays for Aß40 and Aß42 and INNOTEST ELISAs for phosphorylated tau181 (p-tau181) and total tau (t-tau). RESULTS: Our sample comprised 51 participants with mTBI and 85 non-mTBI participants with mean (SD) ages 34.0 (10.1) and 33.5 years (8.9), respectively. All participants but 1 (99%) were male. Differences in CSF AD biomarkers between mTBI and non-mTBI groups were age dependent and most pronounced at older ages (omnibus test p ≤ 0.08). At age 50 years, the mTBI group had lower mean [95% CI] CSF Aß42 and Aß40 than the non-mTBI group by 154 [-12 to 319] and 1864 [610-3,118] pg/mL, respectively. By contrast, CSF p-tau181 and t-tau mean levels remained relatively constant with age in participants with mTBI, while tending to be higher at older ages for the non-mTBI group. The mTBI group also demonstrated poorer cognitive performance at older ages (omnibus p < 0.08): at age 50 years, the mean TMT-B time was higher by 34 seconds [10-58] and the mean CVLT-II short-delay recall was lower by 4.2 points [1.9-6.6]. Poorer verbal memory and verbal fluency performance were associated with lower CSF Aß42 (p ≤ 0.05) in older participants. DISCUSSION: CSF Aß levels decreased in middle-aged veterans with blast-related mTBI. These data suggest that chronic neuropathologic processes associated with blast mTBI share properties in common with pathogenic processes known to portend AD onset, thus raising concern that veterans with blast-related mTBI may develop a dementing disorder later in life.