Stress and traumatic brain injury: An inherent bi-directional relationship with temporal and synergistic complexities

Hair cortisol as a marker of stress in mild traumatic brain injury: a challenging measure

Cortisol is released through activation of the hypothalamic-pituitary-adrenal axis by physiological and psychological stressors, such as mild traumatic brain injury (mTBI). This hormone is accumulated in hair over longer periods of time, reflecting both acute and chronic forms of stress, allowing for retrospective analyses within certain timeframes. The main objectives of this study were to analyze pre- and post-injury hair cortisol concentrations, and to explore possible associations with personality and recovery after mTBI. Hair samples of 61 mTBI patients were collected at 4-6 weeks post-injury and divided into pre- (1 cm) and post-injury (1 cm) segments. For comparison, hair samples of 24 age, sex and education matched healthy controls (HC) were collected and divided into similar segments. Cortisol was quantified using liquid chromatography-tandem mass spectrometry (LC-MS/MS). At two weeks post-injury, post-traumatic symptoms (PTS), emotional distress (anxiety/depression), and the personality trait neuroticism were measured. At six months post-injury, PTS and functional recovery (Glasgow Outcome Scale Extended) were determined. A significant increase in hair cortisol concentration from pre- to post-injury was found for both mTBI patients and HC, likely due to washout effects, with similar concentrations in both groups. Neither hair cortisol, nor the interaction with neuroticism, were associated with long-term PTS or functional recovery. Additionally, no differences in hair cortisol were observed between patients with a higher and lower risk of developing persistent PTS based on a modified Post-Concussion Symptoms Rule (PoCS Rule) including demographics, acute symptoms, pre-injury mental health and head CT. Altogether, our findings do not support the current use of hair cortisol as a potential marker of stress in mTBI.

Perioperative Neurocognitive Disorder in Individuals with a History of Traumatic Brain Injury: Protocol for a Systematic Review and Meta-Analysis

Postoperative neurocognitive disorder (PND) is a cognitive decline after general anesthesia and surgery, influenced by preexisting neurodegenerative conditions, stress, and inflammation. Traumatic brain injury (TBI) is linked to a dysregulated stress response, neuroinflammation, and cognitive issues. Patients with TBI often need extracranial surgeries under general anesthesia (GA), which can increase stress, neuroinflammation, and neurodegenerative changes, raising PND risk. We will search databases like Ovid Medline and Embase for studies on cognitive function in patients with mild to moderate TBI who had extracranial surgeries under general anesthesia (GA). Screening and data extraction will be done manually and with AI-assisted tools (ASReview). Study quality will be assessed using the Newcastle-Ottawa Scale. Statistical analyses will include mean differences, odds ratios, and meta-regression, addressing heterogeneity, sensitivity, and publication bias using Stata/SE. By meta-analyzing clinical studies, we aim to determine if TBI and GA/surgery interact to induce PND. We will use various data sources, subgroup analyses, sensitivity analyses, and meta-regression to assess factors like age, gender, and type of GA/surgery. This meta-analysis will enhance our understanding of PND risks, inform clinical practices, and highlight new research directions. The systematic review is registered in PROSPERO (CRD42024510980).

Metabolic dysfunction contributes to mood disorders after traumatic brain injury

Traumatic brain injury (TBI) presents significant risks concerning mortality and morbidity. Individuals who suffer from TBI may exhibit mood disorders, including anxiety and depression. Both preclinical and clinical research have established correlations between TBI and disturbances in the metabolism of amino acids, lipids, iron, zinc, and copper, which are implicated in the emergence of mood disorders post-TBI. The purpose of this review is to elucidate the impact of metabolic dysfunction on mood disorders following TBI and to explore potential strategies for mitigating anxiety and depression symptoms. We researched the PubMed and Web of Science databases to delineate the mechanisms by which metabolic dysfunction contributes to mood disorders in the context of TBI. Particular emphasis was placed on the roles of glutamate, kynurenine, lipids, iron, zinc, and copper metabolism. Metabolic dysfunction is linked to mood disorders post-TBI through multiple pathways, encompassing the glutamatergic system, the kynurenine pathway, endocannabinoids, iron deposition, iron-related ferroptosis, zinc deficiency, and copper dysregulation. Furthermore, this review addresses the influence of metabolic dysfunction on mood disorders in the elderly demographic following TBI. Targeting metabolic dysfunction for therapeutic intervention appears promising in alleviating symptoms of anxiety and depression that arise after TBI. While further investigation is warranted to delineate the underlying pathophysiologic mechanisms of mood disorders post-TBI, current evidence underscores the potential contribution of metabolic dysfunction to these conditions. Therefore, rectifying metabolic dysfunction represents a viable and strategic approach to addressing mood disorders following TBI.

Pathophysiology, blood biomarkers, and functional deficits after intimate partner violence-related brain injury: Insights from emergency department patients and a new rat model

Intimate partner violence is a serious, but underappreciated, issue that predominantly affects women and often results in concussion (i.e., mild traumatic brain injury). However, concussion in intimate partner violence is unique because it often involves a concomitant strangulation which may exacerbate or alter the physiology and clinical presentation of the brain injury. Therefore, here we conducted human and rodent studies to provide insight into knowledge gaps related to the detection, pathophysiology, and functional consequences of intimate partner violence-related brain injury. We conducted the first study to analyze blood biomarkers and symptoms of brain injury in intimate partner violence patients presenting to an emergency department within 72 h of concussion. Intimate partner violence concussion patients, some of whom had also experienced a concomitant strangulation, had elevated serum neurofilament light and worse brain injury symptoms compared to healthy control, orthopedic trauma, and non-intimate partner violence concussion groups. We also developed the first rat model of non-fatal strangulation and examined the consequences of strangulation and concussion in isolation and in combination on pathophysiology, blood biomarkers, and behavior at 2 h and 1wk post-injury. Rats exposed to combined strangulation and concussion had exacerbated motor and cognitive deficits, neuroinflammation, and serum glial fibrillary acidic protein levels compared with either injury in isolation. Taken together, these rodent findings demonstrate that a concomitant strangulation modifies and exacerbates concussion pathophysiology, biomarkers, and functional consequences. Overall, these findings provide novel insights into intimate partner violence-related brain injury and provides a foundation for future translational studies.

Real-world efficacy of transfusion with liberal or restrictive strategy in traumatic brain injury

OBJECTIVE

The short-term efficacy of red blood cell (RBC) transfusion among general traumatic brain injury (TBI) patients is unclear.

METHODS

We used the MIMIC database to compare the efficacy of liberal (10 g/dL) versus conservative (7 g/dL) transfusion strategy in TBI patients. The outcomes were neurological progression (decrease of Glasgow coma scale (GCS) of at least 2 points) and death within 28 days of ICU admission. Each eligible individual was cloned and assigned each of the replicates to one of the treatment arm. The imbalance induced by informative censoring was adjusted by inverse probability weighting. The standardized, weighted pooled logistic regression with 500 bootstrap resampling was used to estimate the cumulative risk difference and 95% confidence interval (CI).

RESULTS

Of the 1141 eligible individuals, 29.0% received RBC transfusion. Compared with the restrictive group, the liberal strategy reduced early death (3 days: 5%, 95% CI: 2%-7%; 7 days: 6%, 95% CI: 3%-11%); however, no significant difference of mortality risk at 28-day or neurological progression risk at any time points was observed. The risk of coagulopathy at 3 days was increased by 7% (95% CI: 1%-19%) in the liberal group. The subgroup analysis indicated a beneficial effect of liberal transfusion on mortality in hemodynamically unstable patients.

INTERPRETATION

Compared with the restrictive strategy, the liberal strategy does not improve the short-term neurological prognosis and death among patients with TBI in a real-world situation. The liberal strategy may be beneficial to survival at very early stage or in hemodynamically unstable subgroup.

Tentative Causes of Brain and Neuropsychological Alterations in Women Victims of Intimate Partner Violence

Victims of Intimate Partner Violence Against Women (IPVAW) experience neuropsychological and cerebral changes, which have been linked to several tentative causal mechanisms, including elevated cortisol levels, psychopathological disorders, traumatic brain injury (TBI), hypoxic/ischemic brain damage, and medical conditions related to IPVAW. While these mechanisms and their effects on brain function and neuropsychological health are well-documented in other clinical populations, they manifest with unique characteristics in women affected by IPVAW. Specifically, IPVAW is chronic and repeated in nature, and mechanisms are often cumulative and may interact with other comorbid conditions. Thus, in light of existing literature on neuropsychological alterations in other populations, and recognizing the distinct features in women who experience IPVAW, we propose a new theoretical model-the Neuro-IPVAW model. This framework aims to explain the complex interplay between these mechanisms and their impact on cognitive and brain health in IPVAW victims. We anticipate that this theoretical model will be valuable for enhancing our understanding of neuropsychological and brain changes related to intimate partner violence, identifying research gaps in these mechanisms, and guiding future research directions in this area.

Symptoms Associated With Exercise Intolerance and Resting Heart Rate Following Mild Traumatic Brain Injury

OBJECTIVES

People may experience a myriad of symptoms after mild traumatic brain injury (mTBI), but the relationship between symptoms and objective assessments is poorly characterized. This study sought to investigate the association between symptoms, resting heart rate (HR), and exercise tolerance in individuals following mTBI, with a secondary aim to examine the relationship between symptom-based clinical profiles and recovery.

METHODS

Prospective observational study of adults aged 18 to 65 years who had sustained mTBI within the previous 7 days. Symptoms were assessed using the Post-Concussion Symptom Scale, HR was measured at rest, and exercise tolerance was assessed using the Buffalo Concussion Bike Test. Symptom burden and symptom-based clinical profiles were examined with respect to exercise tolerance and resting HR.

RESULTS

Data from 32 participants were assessed (mean age 36.5 ± 12.6 years, 41% female, 5.7 ± 1.1 days since injury). Symptom burden (number of symptoms and symptom severity) was significantly associated with exercise intolerance ( P = .002 and P = .025, respectively). Physiological and vestibular-ocular clinical profile composite groups were associated with exercise tolerance ( P = .001 and P = .014, respectively), with individuals who were exercise intolerant having a higher mean number of symptoms in each profile than those who were exercise tolerant. Mood-related and autonomic clinical profiles were associated with a higher resting HR (>80 bpm) ( P = .048 and P = .028, respectively), suggesting altered autonomic response for participants with symptoms relating to this profile. After adjusting for age and mechanism of injury (sports- or non-sports-related), having a higher mood-related clinical profile was associated with persisting symptoms at 3 months postinjury (adjusted odds ratio = 2.08; 95% CI, 1.11-3.90; P = .013).

CONCLUSION

Symptom-based clinical profiles, in conjunction with objective measures such as resting HR and exercise tolerance, are important components of clinical care for those having sustained mTBI. These results provide preliminary support for the concept that specific symptoms are indicative of autonomic dysfunction following mTBI.

Neurobehavioral Abnormalities in Offspring of Young Adult Male Rats With a History of Traumatic Brain Injury

Children of parents with traumatic brain injury (TBI) are more likely to develop psychiatric disorders. This association is usually attributed to TBI-induced changes in parents' personality and families' social environment. We tested the hypothesis that offspring of young adult male rats with TBI develop neurodevelopmental abnormalities in the absence of direct social contact with sires. Male Sprague-Dawley rats (F0 generation) in the TBI group underwent moderate TBI via a midline fluid percussion injury that involved craniectomy under sevoflurane (SEVO) anesthesia for 40 min on post-natal Day 60 (P60), while F0 rats in the control group were placed in a new cage, one per cage, for the equivalent time duration. A subset of F0 rats was sacrificed on P66 to assess acute changes in hypothalamic-pituitary-adrenal (HPA) axis and inflammation markers. The remaining F0 males were mated with naive females on P90 to generate offspring (F1 generation). The F0 males and F1 males and females were sequentially evaluated in the elevated plus maze, for pre-pulse inhibition of acoustic startle, in the Morris water maze, and for resting and stress levels of serum corticosterone starting on ∼P105 (F0) and ∼P60 (F1), followed by tissue collection for further analyses. Acutely, the F0 TBI males had messenger RNA (mRNA) transcripts altered to support an increased hypothalamic and hippocampal Na+-K+-Cl- (Slc12a2) Cl- importer / K+-2Cl- (Slc12a5) Cl- exporter ratio and decreased hippocampal glucocorticoid receptors (Nr3c1), as well as increased serum levels of corticosterone, interleukin-1β (IL-1β), and biomarkers of activated hippocampal microglia and astrocytes. Long-term, F0 TBI rats exhibited increased corticosterone concentrations at rest and under stress, anxiety-like behavior, impaired sensory-motor gating, and impaired spatial memory. These abnormalities were underpinned by reduced mRNA levels of hypothalamic and hippocampal mineralocorticoid receptors (Nr3c2), hippocampal Nr3c1, and hypothalamic brain-derived neurotrophic factor (Bdnf), as well as elevated serum levels of IL-1β, and biomarkers of activated hippocampal microglia and astrocytes. F1 male offspring of TBI sires exhibited abnormalities in all behavioral tests, while their F1 female counterparts had abnormal pre-pulse inhibition responses only. F1 male offspring of TBI sires also had reduced mRNA levels of hippocampal Nr3c1 and Nr3c2, as well as hypothalamic and hippocampal Bdnf, whereas increases in inflammatory markers were more profound in F1 females. These findings suggest that offspring of sires with a history of a moderate TBI that involved craniectomy under SEVO anesthesia for 40 min, develop sex-dependent neurobehavioral abnormalities in the absence of direct social interaction between the sire and the offspring.

Context is key: glucocorticoid receptor and corticosteroid therapeutics in outcomes after traumatic brain injury

Traumatic brain injury (TBI) is a global health burden, and survivors suffer functional and psychiatric consequences that can persist long after injury. TBI induces a physiological stress response by activating the hypothalamic-pituitary-adrenal (HPA) axis, but the effects of injury on the stress response become more complex in the long term. Clinical and experimental evidence suggests long lasting dysfunction of the stress response after TBI. Additionally, pre- and post-injury stress both have negative impacts on outcome following TBI. This bidirectional relationship between stress and injury impedes recovery and exacerbates TBI-induced psychiatric and cognitive dysfunction. Previous clinical and experimental studies have explored the use of synthetic glucocorticoids as a therapeutic for stress-related TBI outcomes, but these have yielded mixed results. Furthermore, long-term steroid treatment is associated with multiple negative side effects. There is a pressing need for alternative approaches that improve stress functionality after TBI. Glucocorticoid receptor (GR) has been identified as a fundamental link between stress and immune responses, and preclinical evidence suggests GR plays an important role in microglia-mediated outcomes after TBI and other neuroinflammatory conditions. In this review, we will summarize GR-mediated stress dysfunction after TBI, highlighting the role of microglia. We will discuss recent studies which target microglial GR in the context of stress and injury, and we suggest that cell-specific GR interventions may be a promising strategy for long-term TBI pathophysiology.