Diagnosing mild traumatic brain injury using saliva RNA compared to cognitive and balance testing

Anti-miR oligo-mediated detection of human salivary microRNAs for mild traumatic brain injury

Mild traumatic brain injury (mTBI), often resulting from traffic accidents, workplace incidents, sports, or recreational activities, is a neurological condition that significantly impacts the daily lives of many individuals. The absence of reliable biomarkers and the non-specific nature of mTBI symptoms pose challenges for accurate diagnosis, leading to undetected cases and potential long-term consequences. Current diagnostic approaches, including neuroimaging, serum biomarkers, and cognitive assessments, suffer from cost, invasiveness, and sensitivity limitations. To address this, we developed a novel electrochemical detection platform for salivary microRNAs (miRNAs), offering a rapid, non-invasive, and cost-effective alternative for mTBI diagnosis. Key challenges in point-of-care miRNA detection lie in low abundance, short length, sequence complementarity, degradation, and amplification-free detection with high sensitivity and specificity. This platform technology introduces a de novo-synthesized, conductive carboxyl-functionalized thiophene polymer (AAOT:PSS)-coated gold electrode, enabling the covalent attachment of streptavidin-linked, biotinylated anti-miRNAs with methylene blue as the electrochemical reporter. This system successfully detected picomolar concentrations of mTBI-associated miRNAs (miR-let7a, miR-30e, miR-21) in saliva, outperforming traditional methods and establishing salivary miRNAs as highly reliable biomarkers for mTBI. Our approach leverages the mTBI-induced upregulation of miR-let7a, miR-30e, miR-21 as proof-of-concept targets with scope of multiplexing while achieving 100% sensitivity and specificity in patient-derived samples validated via PCR and clinical assessments.

Efficacy of biomarkers and imaging techniques for the diagnosis of traumatic brain injury: challenges and opportunities

Concussion is a pervasive health issue in the present day. Increased prevalence in recent years has indicated a need to improve the current understanding of minor traumatic brain injury (mTBI). Effort has been devoted to understanding the underlying pathophysiology of TBIs, but some mechanisms remain unknown. Potentially lethal secondary effects of concussion include second impact syndrome and chronic traumatic encephalopathy (CTE), introducing long-term considerations for the management of mTBI. Post-concussion syndrome is another long-term consequence of concussion and may be influenced by both neuroinflammation and hormonal imbalances resulting from head trauma. Genetically mutated apolipoprotein E may also contribute to the severity and persistence of concussion symptoms, perhaps even acting as a risk factor for CTE. As it stands, the diagnosis of concussion is nuanced, depending primarily on subjective diagnostic tools that incorporate patient-reported symptoms and neurocognitive tests. Diagnostic tools provide some assistance in concussion diagnosis, but still lack accuracy and inherently leave room for uncertainty. To mitigate some of this uncertainty, considerable research has been devoted to the development of methods to diagnose concussions objectively. Biomarkers such as S100 calcium binding protein B (S100B), glial fibrillary acidic protein (GFAP), neurofilament light protein (Nf-L), interleukin-6 (IL-6) and microRNAs (miRNAs) as well as imaging techniques including diffusion tensor imaging (DTI) and blood-oxygen level dependent functional magnetic resonance imaging (BOLD-fMRI) show great promise in this regard. This review aims to compile the relevant literature in these areas in the hopes of being used as a reference point for future research regarding concussions.

TRANSCENDENT (Transforming Research by Assessing Neuroinformatics across the Spectrum of Concussion by Embedding iNterdisciplinary Data-collection to Enable Novel Treatments): protocol for a prospective observational cohort study of concussion patients with embedded comparative effectiveness research within a network of learning health system concussion clinics in Canada

INTRODUCTION

Concussion affects over 400 000 Canadians annually, with a range of causes and impacts on health-related quality of life. Research to date has disproportionately focused on athletes, military personnel and level I trauma centre patients, and may not be applicable to the broader community. The TRANSCENDENT Concussion Research Program aims to address patient- and clinician-identified research priorities, through the integration of clinical data from patients of all ages and injury mechanisms, patient-reported outcomes and objective biomarkers across factors of intersectionality. Seeking guidance from our Community Advisory Committee will ensure meaningful patient partnership and research findings that are relevant to the wider concussion community.

METHODS AND ANALYSIS

This prospective observational cohort study will recruit 5500 participants over 5 years from three 360 Concussion Care clinic locations across Ontario, Canada, with a subset of participants enrolling in specific objective assessments including testing of autonomic function, exercise tolerance, vision, advanced neuroimaging and fluid biomarkers. Analysis will be predicated on pre-specified research questions, and data shared with the Ontario Brain Institute's Brain-CODE database. This work will represent one of the largest concussion databases to date, and by sharing it, we will advance the field of concussion and prevent siloing within brain health research.

ETHICS AND DISSEMINATION

This study was approved by the Children's Hospital of Eastern Ontario Research Ethics Board and preregistered on OSF (25 June 2024); https://doi.org/10.17605/OSF.IO/HYDZC. Dissemination of findings will be multifaceted, including conference presentations, peer-reviewed publications and sharing of adapted materials (eg, videos, infographics, plain language summaries) with community groups and key knowledge users.

Tailored Anti-miR Decorated Covalent Organic Framework Enables Electrochemical Detection of Salivary miRNAs for Mild Traumatic Brain Injury

MicroRNAs (miRNAs) play pivotal role as biomarkers for various diseases, with salivary miRNAs offering a non-invasive diagnostic tool. For mild traumatic brain injury (mTBI), salivary miRNAs like miR-let7a, miR-21, and miR-30e show promise for early detection of subtle injuries lacking reliable indicators. To advance the detection of mTBI-related salivary miRNAs, this study integrates anti-miRNA and miRNA hybridization-based sensing with the development of a nanoscale covalent-organic framework (COF) platform. COFs, with their highly customizable structures, large surface area, and biocompatibility, serve as a versatile foundation for biosensing applications. Here, post-synthetic modification (PSM) of COFs is introduced for essential covalent conjugation of streptavidin for further immobilization of methylene blue-labeled and biotinylated Anti-miRNAs. Furthermore, the layer-by-layer assembly of conductive polymers enhanced the biosensor's electrical performance, enabling ultrasensitive and multiplexed detection of salivary miRNAs. Validated with samples from mixed martial arts participants and confirmed by polymerase chain reaction (PCR), this COF-based platform demonstrates robust accuracy and reliability. By combining COF functionalization with advanced electrode design, it offers a powerful, non-invasive solution for early mTBI detection and broader biomedical applications.

Association of Longitudinal Oral Microbiome Activity and Pediatric Concussion Recovery

Mild traumatic brain injury (mTBI) results in a constellation of symptoms commonly referred to as a concussion. It is unclear why certain individuals experience persistent symptoms. Given the growing evidence linking the microbiome with cognition and inflammation, we examined whether longitudinal microbiome patterns were associated with concussion symptoms. A cohort study of 118 children (aged 7-21 years) was conducted. Symptoms were assessed at three timepoints post-injury (4, 11, and 30 days) using the Post-Concussion Symptom Inventory. Saliva microbial activity was measured at each timepoint using RNA sequencing. A linear mixed model assessed the relationship between microbial activity and symptom burden while controlling for age, sex, and days post-mTBI. The participants' mean age was 16 (±3) years. The symptom burden decreased across all three timepoints (25 ± 22, 13 ± 17, and 5 ± 12). The longitudinal symptom burden was associated with elevated activity of Lactobacillus (F = 5.47; adj. p = 0.020) and Saccharomyces (F = 6.79; adj. p = 0.020) and reduced activity of Micrococcus (F = 7.94, adj. p = 0.015). These results do not establish a causative relationship, or support the use of microbial measures as a concussion test. Further studies are needed to explore the role of the gut-brain axis in mTBI.

Epigenetics of concussion: A systematic review

BACKGROUND

Concussion is the most common neurological disorder affecting millions of people globally each year. Identifying epigenetic mechanisms influencing concussion incidence, severity and recovery could provide diagnostic and prognostic insight into this injury.

OBJECTIVES

This systematic review aims to identify the epigenetic mechanisms underpinning concussion.

METHODS

Seven electronic databases; PubMed, MEDLINE, CINAHL, Cochrane library, SPORTDiscus, Scopus and Web of Science were searched for studies that investigated the epigenetic mechanisms of concussion and its underlying neuropathology.

RESULTS

Based on inclusion and exclusion criteria, 772 titles were independently analysed by two of the authors to a final list of 28 studies that totaled 3042 participants. We observed separate associations between sncRNAs, methylation, histone modification and concussion. Overall, 204 small non-coding RNAs were significantly dysregulated between concussed participants and controls or between concussion participants with no post-concussive symptoms and those with post-concussive symptoms. From these, 37 were reported in more than one study and 23 of these were expressed in a consistent direction with at least one further study. Ingenuity pathway analysis identified 10 miRNAs known to regulate 15 genes associated with human neurological pathologies. Two studies found significant changes in global methylation in concussed participants and one study found a decrease in H3K27Me3 in the context of DNA damage and concussion.

CONCLUSIONS

The review findings suggest that epigenetic mechanisms may play an important role in the pathophysiological mechanisms that could influence outcome, recovery, and potential long-term consequences of concussion for individuals.

Advancements in diagnosing Post-concussion Syndrome: insights into epidemiology, pathophysiology, neuropathology, neuroimaging, and salivary biomarkers

Post-Concussion Syndrome (PCS) represents a complex constellation of symptoms that persist following a concussion or mild traumatic brain injury (mTBI), with significant implications for patient care and outcomes. Despite its prevalence, diagnosing PCS presents considerable challenges due to the subjective nature of symptoms, the absence of specific diagnostic tests, and the overlap with other neurological and psychiatric conditions. This review explores the multifaceted diagnostic challenges associated with PCS, including the heterogeneity of symptom presentation, the limitations of current neuroimaging techniques, and the overlap of PCS symptoms with other disorders. We also discuss the potential of emerging biomarkers and advanced imaging modalities to enhance diagnostic accuracy and provide a more objective basis for PCS identification. Additionally, the review highlights the importance of a multidisciplinary approach in the diagnosis and management of PCS, integrating clinical evaluation with innovative diagnostic tools to improve patient outcomes. Through a comprehensive analysis of current practices and future directions, this review aims to shed light on the complexities of PCS diagnosis and pave the way for improved strategies in the identification and treatment of this condition.

Portable six-channel laser speckle system for simultaneous measurement of cerebral blood flow and volume with potential applications in characterization of brain injury

Significance

Cerebral blood flow (CBF) and cerebral blood volume (CBV) are key metrics for regional cerebrovascular monitoring. Simultaneous, non-invasive measurement of CBF and CBV at different brain locations would advance cerebrovascular monitoring and pave the way for brain injury detection as current brain injury diagnostic methods are often constrained by high costs, limited sensitivity, and reliance on subjective symptom reporting.

Aim

We aim to develop a multi-channel non-invasive optical system for measuring CBF and CBV at different regions of the brain simultaneously with a cost-effective, reliable, and scalable system capable of detecting potential differences in CBF and CBV across different regions of the brain.

Approach

The system is based on speckle contrast optical spectroscopy and consists of laser diodes and board cameras, which have been both tested and investigated for safe use on the human head. Apart from the universal serial bus connection for the camera, the entire system, including its battery power source, is integrated into a wearable headband and is powered by 9-V batteries.

Results

The temporal dynamics of both CBF and CBV in a cohort of five healthy subjects were synchronized and exhibited similar cardiac period waveforms across all six channels. The potential use of our six-channel system for detecting the physiological sequelae of brain injury was explored in two subjects, one with moderate and one with significant structural brain damage, where the six-point CBF and CBV measurements were referenced to structural magnetic resonance imaging (MRI) scans.

Conclusions

We pave the way for a viable multi-point optical instrument for measuring CBF and CBV. Its cost-effectiveness allows for baseline metrics to be established prior to injury in populations at risk for brain injury.

Portable Six-Channel Laser Speckle System for Simultaneous Cerebral Blood Flow and Volume Measurement with Potential Application for Characterization of Brain Injury

In regional cerebrovascular monitoring, cerebral blood flow (CBF) and cerebral blood volume (CBV) are key metrics. Simultaneous, non-invasive measurement of CBF and CBV at different brain locations would advance cerebrovascular monitoring and pave the way for brain injury detection, as current brain injury diagnostic methods are often constrained by high costs, limited sensitivity, and reliance on subjective symptom reporting. This study's aim is to develop a multi-channel non-invasive optical system for measuring CBF and CBV at different regions of the brain simultaneously with a cost-effective, reliable, and scalable system capable of detecting potential differences in CBF and CBV across different regions of the brain. The system is based on speckle contrast optical spectroscopy (SCOS) and consists of laser diodes and board cameras which have been both tested and investigated for safe use on the human head. Results on a cohort of five healthy subjects indicated that the dynamics of both CBF and CBV were synchronized and exhibited similar cardiac period waveforms across all six channels. As a preliminary investigation, we also explored the potential use of our six-channel system for detecting the physiological sequela of brain injury, involving a subject with significant structural brain damage compared to another with lesser structural brain damage. The six-point CBF and CBV measurements were compared to MRI scans, revealing that regions with altered blood dynamics closely correlated with the injury sites identified by MRI.

Understanding how traumatic brain injury-related changes in fluid biomarkers affect quality of life outcomes in veterans: a prospective observational trial protocol (UNTANGLE)

INTRODUCTION

Traumatic brain injury (TBI) is a major cause of disability, with annual global incidence estimated as 69 million people. Survivors can experience long-term visual changes, altered mental state, neurological deficits and long-term effects that may be associated with mental illness. TBI is prevalent in military personnel due to gunshot wounds, and blast injury. This study aims to evaluate the relationship between evolving visual, biochemical and mental health changes in both military veterans and civilians, suffering from TBI, and detect preliminary indicators of prognosis for TBI recovery, and quality-of-life outcomes.

METHODS AND ANALYSIS

UNTANGLE is a 24-month prospective observational pilot study recruiting three patient groups: civilians with acute moderate-severe TBI, military veterans with diagnosis of a previous TBI and a control group of civilians or veterans with no history of a previous TBI. Patients will undergo visual, biochemical and mental health assessments, as well as patient-reported quality of life outcome measures over the course of a 1-year follow-up period.

ETHICS AND DISSEMINATION

Ethical approval has been obtained from the Health Research Authority and Health and Care Research Wales with a REC reference number of 23/NW/0203. The results of the study will be presented at scientific meetings and published in peer-reviewed journals, including both civilian and military-related publications. We will also present our findings at national and international meetings of learnt neuroscience and neuropsychiatry and military societies. We anticipate that our pilot study will inform a larger study on the long-term outcomes of TBI and quality of life, specific to military veterans, such that potential interventions may be accessed as quickly as possible.

TRIAL REGISTRATION NUMBER

ISRCTN13276511.

Biofluid, Imaging, Physiological, and Functional Biomarkers of Mild Traumatic Brain Injury and Subconcussive Head Impacts

Post-concussive symptoms are frequently reported by individuals who sustain mild traumatic brain injuries (mTBIs) and subconcussive head impacts, even when evidence of intracranial pathology is lacking. Current strategies used to evaluate head injuries, which primarily rely on self-report, have a limited ability to predict the incidence, severity, and duration of post-concussive symptoms that will develop in an individual patient. In addition, these self-report measures have little association with the underlying mechanisms of pathology that may contribute to persisting symptoms, impeding advancement in precision treatment for TBI. Emerging evidence suggests that biofluid, imaging, physiological, and functional biomarkers associated with mTBI and subconcussive head impacts may address these shortcomings by providing more objective measures of injury severity and underlying pathology. Interest in the use of biomarker data has rapidly accelerated, which is reflected by the recent efforts of organizations such as the National Institute of Neurological Disorders and Stroke and the National Academies of Sciences, Engineering, and Medicine to prioritize the collection of biomarker data during TBI characterization in acute-care settings. Thus, this review aims to describe recent progress in the identification and development of biomarkers of mTBI and subconcussive head impacts and to discuss important considerations for the implementation of these biomarkers in clinical practice.

Systematic review and dosage analysis: hyperbaric oxygen therapy efficacy in the treatment of posttraumatic stress disorder

Background

Studies of hyperbaric oxygen therapy (HBOT) treatment of mild traumatic brain injury persistent postconcussion syndrome in military and civilian subjects have shown simultaneous improvement in posttraumatic stress disorder (PTSD) or PTSD symptoms, suggesting that HBOT may be an effective treatment for PTSD. This is a systematic review and dosage analysis of HBOT treatment of patients with PTSD symptoms.

Methods

PubMed, CINAHL, and the Cochrane Systematic Review Database were searched from September 18 to November 23, 2023, for all adult clinical studies published in English on HBOT and PTSD. Randomized trials and studies with symptomatic outcomes were selected for final analysis and analyzed according to the dose of oxygen and barometric pressure on symptom outcomes. Outcome assessment was for statistically significant change and Reliable Change or Clinically Significant Change according to the National Center for PTSD Guidelines. Methodologic quality and bias were determined with the PEDro Scale.

Results

Eight studies were included, all with < 75 subjects/study, total 393 subjects: seven randomized trials and one imaging case-controlled study. Six studies were on military subjects, one on civilian and military subjects, and one on civilians. Subjects were 3-450 months post trauma. Statistically significant symptomatic improvements, as well as Reliable Change or Clinically Significant changes, were achieved for patients treated with 40-60 HBOTS over a wide range of pressures from 1.3 to 2.0 ATA. There was a linear dose-response relationship for increased symptomatic improvement with increasing cumulative oxygen dose from 1002 to 11,400 atmosphere-minutes of oxygen. The greater symptomatic response was accompanied by a greater and severe reversible exacerbation of emotional symptoms at the highest oxygen doses in 30-39% of subjects. Other side effects were transient and minor. In three studies the symptomatic improvements were associated with functional and anatomic brain imaging changes. All 7 randomized trials were found to be of good-highest quality by PEDro scale scoring.

Discussion

In multiple randomized and randomized controlled clinical trials HBOT demonstrated statistically significant symptomatic improvements, Reliable Changes, or Clinically Significant Changes in patients with PTSD symptoms or PTSD over a wide range of pressure and oxygen doses. The highest doses were associated with a severe reversible exacerbation of emotional symptoms in 30-39% of subjects. Symptomatic improvements were supported by correlative functional and microstructural imaging changes in PTSD-affected brain regions. The imaging findings and hyperbaric oxygen therapy effects indicate that PTSD can no longer be considered strictly a psychiatric disease.

Non-invasive fluid biomarkers in the diagnosis of mild traumatic brain injury (mTBI): a systematic review

BACKGROUND

Despite approximately 55.9 million annual mild traumatic brain injuries (mTBIs) worldwide, the accurate diagnosis of mTBI continues to challenge clinicians due to symptom ambiguity, reliance on subjective report and presentation variability. Non-invasive fluid biomarkers of mTBI offer a biological measure to diagnose and monitor mTBI without the need for blood draws or neuroimaging. The objective of this study is to systematically review the utility of such biomarkers to diagnose mTBI and predict disease progression.

METHODS

A systematic review performed in PubMed, Scopus, Cochrane and Web of Science followed by a manual search of references without a specified timeframe. Search strings were generated and run (27 June 2022) by a research librarian. Studies were included if they: (1) included human mTBI subjects, (2) assessed utility of a non-invasive biomarker and (3) published in English. Exclusion criteria were (1) non-mTBI subjects, (2) mTBI not assessed separately from moderate/severe TBI, (3) required intracranial haemorrhage or (4) solely assesses genetic susceptibility to mTBI.

RESULTS

A total of 29 studies from 27 subject populations (1268 mTBI subjects) passed the inclusion and exclusion criteria. Twelve biomarkers were studied. Salivary RNAs, including microRNA, were assessed in 11 studies. Cortisol and melatonin were assessed in four and three studies, respectively. Eight salivary and two urinary biomarkers contained diagnostic or disease monitoring capability.

DISCUSSION

This systematic review identified several salivary and urinary biomarkers that demonstrate the potential to be used as a diagnostic, prognostic and monitoring tool for mTBI. Further research should examine miRNA-based models for diagnostic and predictive utility in patients with mTBI.

PROSPERO REGISTRATION NUMBER

CRD42022329293.

Post-traumatic headache pathophysiology in paediatric concussion: A systematic review

Post-traumatic headache (PTH) represents the most common acute and persistent symptom following concussion in children, yet the underlying pathophysiology remains unclear. This systematic review sought to: (i) rigorously examine the current evidence of PTH pathophysiology in paediatric concussion (0-18 years), (ii) assess the quality of evidence, and (iii) provide directions for future research in accordance with PRISMA guidelines. Eligible studies (n = 19) totalling 1214 concussion participants investigated cerebrovascular function (n = 6), white matter integrity (n = 3), functional connectivity (n = 3), electrophysiology (n = 1), neurometabolics (n = 2), biological fluid markers (n = 4), vestibular and oculomotor function (n = 4); two studies used a multi-modal approach. Majority of studies were rated as fair quality (90%) and Level 3 evidence (84%). The true underlying mechanisms of PTH following paediatric concussion remain unclear. Overall quality of the available evidence is generally weak with a fair risk of bias and characterised by relative scarcity and lack of specificity of PTH pathophysiology. Future research is required to rigorously isolate pathophysiology specific to PTH with strict adherence to clinical definitions and standardised measurement tools of PTH.

Salivary microRNA as a prospective tool for concussion diagnosis and management: A scoping review

BACKGROUND

Despite increased efforts directed toward research, concussions are a growing concern and can be a complex injury for healthcare professionals to manage. Current practices are largely dependent on patients self-reporting symptoms and a clinical assessment, which uses objective tools that lack effectiveness. With the demonstrated effects of concussions, it is imperative that a more valid or reliable objective tool, like a clinical biomarker, be identified to improve outcomes. One potential biomarker that has shown promise is salivary microRNA. However, there is no objective consensus as to which microRNA offers the most clinical value regarding concussions, hence this review. Therefore, the purpose of this scoping review was to identify salivary miRNAs associated with concussions.

METHODS

Two independent reviewers performed a literature search to identify research articles. Studies using human subjects, collected salivary miRNA, and were published in English were included. Data of interest were salivary miRNA, collection timing, and relation to concussion diagnosis or management.

RESULTS

This paper reviews nine studies that analyzed salivary miRNA for concussion diagnosis and management.

CONCLUSIONS

In total, the studies have identified 49 salivary miRNA that show promise in assisting with concussion practices. With continued research, the use of salivary miRNA may enhance clinicians' abilities to diagnose and manage concussions.

Refinement of saliva microRNA biomarkers for sports-related concussion

BACKGROUND

Recognizing sport-related concussion (SRC) is challenging and relies heavily on subjective symptom reports. An objective, biological marker could improve recognition and understanding of SRC. There is emerging evidence that salivary micro-ribonucleic acids (miRNAs) may serve as biomarkers of concussion; however, it remains unclear whether concussion-related miRNAs are impacted by exercise. We sought to determine whether 40 miRNAs previously implicated in concussion pathophysiology were affected by participation in a variety of contact and non-contact sports. Our goal was to refine a miRNA-based tool capable of identifying athletes with SRC without the confounding effects of exercise.

METHODS

This case-control study harmonized data from concussed and non-concussed athletes recruited across 10 sites. Levels of salivary miRNAs within 455 samples from 314 individuals were measured with RNA sequencing. Within-subjects testing was used to identify and exclude miRNAs that changed with either (a) a single episode of exercise (166 samples from 83 individuals) or (b) season-long participation in contact sports (212 samples from 106 individuals). The miRNAs that were not impacted by exercise were interrogated for SRC diagnostic utility using logistic regression (172 samples from 75 concussed and 97 non-concussed individuals).

RESULTS

Two miRNAs (miR-532-5p and miR-182-5p) decreased (adjusted p < 0.05) after a single episode of exercise, and 1 miRNA (miR-4510) increased only after contact sports participation. Twenty-three miRNAs changed at the end of a contact sports season. Two of these miRNAs (miR-26b-3p and miR-29c-3p) were associated (R > 0.50; adjusted p < 0.05) with the number of head impacts sustained in a single football practice. Among the 15 miRNAs not confounded by exercise or season-long contact sports participation, 11 demonstrated a significant difference (adjusted p < 0.05) between concussed and non-concussed participants, and 6 displayed moderate ability (area under curve > 0.70) to identify concussion. A single ratio (miR-27a-5p/miR-30a-3p) displayed the highest accuracy (AUC = 0.810, sensitivity = 82.4%, specificity = 73.3%) for differentiating concussed and non-concussed participants. Accuracy did not differ between participants with SRC and non-SRC (z = 0.5, p = 0.60).

CONCLUSION

Salivary miRNA levels may accurately identify SRC when not confounded by exercise. Refinement of this approach in a large cohort of athletes could eventually lead to a non-invasive, sideline adjunct for SRC assessment.

Review on the Role of Salivary Biomarkers in the Diagnosis of Mild Traumatic Brain Injury and Post-Concussion Syndrome

(1) Background: While mild traumatic brain injuries (TBIs) are a major public health issue, post-concussion syndrome (PCS) remains a controversial entity. In both cases, the clinical diagnosis is mainly based on the symptoms and brain imaging evaluation. The current molecular biomarkers were described from blood and cerebrospinal fluid (CSF), yet both fluid collection methods are invasive. Saliva could be preferred in molecular diagnosis due to its non-invasive and non-expensive methods of acquisition, transport, and samples processing. (2) Objectives: In the present study, we aimed to review the latest developments in salivary biomarkers and their potential role in diagnosing mild TBIs, and PCS. (3) Results: In TBIs and PCS, a few novel studies focusing on salivary biomarkers have emphasized their importance in diagnosis. The previous studies mainly focused on micro RNAs, and only a few on extracellular vesicles, neurofilament light chain, and S100B. (4) Conclusions: The combination between salivary biomarkers, clinical history and examination, self-reported symptoms, and cognitive/balance testing can provide a non-invasive alternative diagnostic methodology, as compared to the currently approved plasma and cerebrospinal fluid biomarkers.

Increased level of exosomal miR-20b-5p derived from hypothermia-treated microglia promotes neurite outgrowth and synapse recovery after traumatic brain injury

Mild hypothermia has been proven to inhibit microglia activation after TBI. Exosomal microRNA derived from microglia played a critical role in promoting neurite outgrowth and synapse recovery. Here, we aimed to investigate the role of microRNAs in microglial exosomes after hypothermia treatment on neuronal regeneration after TBI. For in vitro study, stretch-injured neurons were co-cultured with microglial exosomes. For in vivo study, C57BL/6 mice were under controlled cortical impact and injected with microglial exosomes. The results showed that MG-LPS-EXO^HT increased the number of dendrite branches and total length of dendrites both in vitro and in vivo, elevated the expression levels of PSD-95 and GluR1 in stretch-injured neurons, and increased spine density in the pericontusion region. Moreover, MG-LPS-EXO^HT improved motor function and motor coordination. A high-throughput sequencing showed that miR-20b-5p was upregulated in MG-LPS-EXO^HT. Elevating miR-20b-5p promoted neurite outgrowth and synapse recovery of injured neurons both in vitro and in vivo. Following mechanistic study demonstrated that miR-20b-5p might promote neurite outgrowth and synapse recovery by directly targeting PTEN and activating PI3K-AKT pathway. In conclusion, mild hypothermia could modify the microRNA prolife of exosomes derived from LPS activated BV2 cells. Furthermore, high level of microglial exosomal miR-20b-5p induced by mild hypothermia could transfer into injured neurons and promote neurite outgrowth and synapse recovery after TBI via activating the PI3K-AKT pathway by suppressing PTEN expression.

Are tai chi and qigong effective in the treatment of TBI? A systematic review protocol

Background

Traumatic brain injury (TBI) adversely affects both young and old and is a growing public health issue. A number of recent trends in managing TBI, such as recommending sub-threshold aerobic activity, tailoring multi-modal treatment strategies, and studying the possible role of low-grade inflammation in those with persistent symptoms, all suggest that the physical and cognitive exercise of tai chi/qigong could have benefit.

Method

Designed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, the following databases will be searched: MEDLINE, CINAHL, Cochrane Library, Embase, China National Knowledge Infrastructure Database, Wanfang Database, Chinese Scientific Journal Database, and Chinese Biomedical Literature Database. All clinical trials on mild, moderate and/or severe TBI with tai chi and/or qigong as the treatment group and any comparison group, in any setting will be included. Four reviewers will independently select studies; two reviewers for the English and two for the Chinese databases. Cochrane-based risk of bias assessments will be conducted on all included studies. An analysis will then be conducted with the grading of recommendation, assessment, development, and evaluation (GRADE) instrument.

Results

This review will summarize the clinical trial evidence on tai chi/qigong for TBI including type of TBI, age/sex of participants, type and length of intervention and comparator, outcome measures, and any adverse events. The risk of bias will be considered, and the strengths and weaknesses of each trial will be analyzed.

Discussion

The results of this review will be considered with respect to whether there is enough evidence of benefit to merit a more definitive randomized controlled trial.Systematic Review Registration: PROSPERO [CRD42022364385].

Diagnostic Competence of Creatine Kinase BB, in Mild Traumatic Brain Injury and its Prognostic Value

Background

Due to the very high and increasing prevalence, essential complications, and risk factors for psychiatric disorders, it is necessary to introduce screening tests for diagnosing and predicting mild traumatic brain injury (mTBI) prognosis.

Materials and Methods

After completing the consent form and recording information and examination findings of patients with mild trauma, venous blood samples were taken from these patients. The samples were measured by observing the cold chain. After 3 months from mTBI, the post concussion symptoms questionnaire (PCSQ) and the short form 36 (SF-36) questionnaire for physical and mental evaluations were performed. Statistical tests analyzed the relationship between different variables and serum Creatine kinase BB (CKBB) levels.

Results

Statistic analyses showed no relation between CKBB level of serum and age, gender, level of consciousness, PCSQ, and SF 36 scale, and the interval between trauma and arrival to the hospital. Further, there is a significant correlation between CK-BB levels and intracranial damage based on Fisher's exact test.

Conclusion

This study and following more significant considerations can introduce a serum-based biomarker panel that can accurately differentiate patients with complicated mTBI from those with uncomplicated.

Putting the "mi" in omics: discovering miRNA biomarkers for pediatric precision care

In the past decade, growing interest in micro-ribonucleic acids (miRNAs) has catapulted these small, non-coding nucleic acids to the forefront of biomarker research. Advances in scientific knowledge have made it clear that miRNAs play a vital role in regulating cellular physiology throughout the human body. Perturbations in miRNA signaling have also been described in a variety of pediatric conditions-from cancer, to renal failure, to traumatic brain injury. Likewise, the number of studies across pediatric disciplines that pair patient miRNA-omics with longitudinal clinical data are growing. Analyses of these voluminous, multivariate data sets require understanding of pediatric phenotypic data, data science, and genomics. Use of machine learning techniques to aid in biomarker detection have helped decipher background noise from biologically meaningful changes in the data. Further, emerging research suggests that miRNAs may have potential as therapeutic targets for pediatric precision care. Here, we review current miRNA biomarkers of pediatric diseases and studies that have combined machine learning techniques, miRNA-omics, and patient health data to identify novel biomarkers and potential therapeutics for pediatric diseases. IMPACT: In the following review article, we summarized how recent developments in microRNA research may be coupled with machine learning techniques to advance pediatric precision care.

Serum microRNAs associated with concussion in football players

Mild Traumatic Brain Injury (mild TBI)/concussion is a common sports injury, especially common in football players. Repeated concussions are thought to lead to long-term brain damage including chronic traumatic encephalopathy (CTE). With the worldwide growing interest in studying sport-related concussion the search for biomarkers for early diagnosis and progression of neuronal injury has also became priority. MicroRNAs are short, non-coding RNAs that regulate gene expression post-transcriptionally. Due to their high stability in biological fluids, microRNAs can serve as biomarkers in a variety of diseases including pathologies of the nervous system. In this exploratory study, we have evaluated changes in the expression of selected serum miRNAs in collegiate football players obtained during a full practice and game season. We found a miRNA signature that can distinguish with good specificity and sensitivity players with concussions from non-concussed players. Furthermore, we found miRNAs associated with the acute phase (let-7c-5p, miR-16-5p, miR-181c-5p, miR-146a-5p, miR-154-5p, miR-431-5p, miR-151a-5p, miR-181d-5p, miR-487b-3p, miR-377-3p, miR-17-5p, miR-22-3p, and miR-126-5p) and those whose changes persist up to 4 months after concussion (miR-17-5p and miR-22-3p).

Systematic Review of the Diagnostic and Clinical Utility of Salivary microRNAs in Traumatic Brain Injury (TBI)

Research in traumatic brain injury (TBI) is an urgent priority, as there are currently no TBI biomarkers to assess the severity of injury, to predict outcomes, and to monitor recovery. Small non-coding RNAs (sncRNAs) including microRNAs can be measured in saliva following TBI and have been investigated as potential diagnostic markers. The aim of this systematic review was to investigate the diagnostic or prognostic ability of microRNAs extracted from saliva in human subjects. PubMed, Embase, Scopus, PsycINFO and Web of Science were searched for studies that examined the association of saliva microRNAs in TBI. Original studies of any design involving diagnostic capacity of salivary microRNAs for TBI were selected for data extraction. Nine studies met inclusion criteria, with a heterogeneous population involving athletes and hospital patients, children and adults. The studies identified a total of 188 differentially expressed microRNAs, with 30 detected in multiple studies. MicroRNAs in multiple studies involved expression change bidirectionality. The study design and methods involved significant heterogeneity that precluded meta-analysis. Early data indicates salivary microRNAs may assist with TBI diagnosis. Further research with consistent methods and larger patient populations is required to evaluate the diagnostic and prognostic potential of saliva microRNAs.

Confounding Factors Impacting microRNA Expression in Human Saliva: Methodological and Biological Considerations

There is growing interest in saliva microRNAs (miRNAs) as non-invasive biomarkers for human disease. Such an approach requires understanding how differences in experimental design affect miRNA expression. Variations in technical methodologies, coupled with inter-individual variability may reduce study reproducibility and generalizability. Another barrier facing salivary miRNA biomarker research is a lack of recognized “control miRNAs”. In one of the largest studies of human salivary miRNA to date (922 healthy individuals), we utilized 1225 saliva samples to quantify variability in miRNA expression resulting from aligner selection (Bowtie1 vs. Bowtie2), saliva collection method (expectorated vs. swabbed), RNA stabilizer (presence vs. absence), and individual biological factors (sex, age, body mass index, exercise, caloric intake). Differential expression analyses revealed that absence of RNA stabilizer introduced the greatest variability, followed by differences in methods of collection and aligner. Biological factors generally affected a smaller number of miRNAs. We also reported coefficients of variations for 643 miRNAs consistently present in saliva, highlighting several salivary miRNAs to serve as reference genes. Thus, the results of this analysis can be used by researchers to optimize parameters of salivary miRNA measurement, exclude miRNAs confounded by numerous biologic factors, and identify appropriate miRNA controls.

REFINEMENT OF SALIVA MI-RNA BIOMARKERS FOR SPORT-RELATED CONCUSSION

ABSTRACT Introduction: The changes in brain structure caused by a sports-related concussion may initially be indistinguishable, however, the irreversible deleterious effects are noted in the long term. An early diagnosis may provide the patient with a better recovery chance and increased survival. For this purpose, this paper studies the feasibility of a diagnosis for concussion by microRNA (mi-RNA) biomarkers contained in the saliva of athletes. Objective: Verify whether salivary miRNAs could be considered good biomarkers for sports concussion. Methodology: Salivary mi-RNA levels were determined from 120 saliva samples of 120 players. There were 43 with a diagnosis of concussion and 77 without a diagnosis of concussion. Samples from players with a concussion were collected 30 minutes prior to activity, samples from individuals who did not engage in physical activity were also compared. Results: On the evaluation of 30 miRNA from individuals with a concussion between contact and non-contact sports there was high detection reliability(P<.05). Both miR-532-5p and miR-182-5p showed reduced amounts of physical activity. The miRNA-532-5p and miRNA-182-5p show significant results among 43 subjects from pre-exercise to post-exercise. The miRNA-4510 showed a significant result (p < 0.05) between contact and non-contact sport types. The amount of miRNA-4510 expanded in 20 individuals in the contact sport at post-exercise but remained normal in the non-contact sports group. Conclusion: The salivary miRNAs are reliable biomarkers for concussion. Evidence Level II; Therapeutic Studies – Investigating the results.

Defining Biological Phenotypes of Mild Traumatic Brain Injury Using Saliva MicroRNA Profiles

Concussion is a heterogeneous injury that relies predominantly on subjective symptom reports for patient assessment and treatment. Developing an objective, biological test could aid phenotypic categorization of concussion patients, leading to advances in personalized treatment. This prospective multi-center study employed saliva micro-ribonucleic acid (miRNA) levels to stratify 251 individuals with concussion into biological subgroups. Using miRNA biological clusters, our objective was to assess for differences in medical/demographic characteristics, symptoms, and functional measures of balance and cognition. The miRNAs that best defined each cluster were used to identify physiological pathways that characterized each cluster. The 251 participants (mean age: 18 ± 7 years; 57% male) were optimally grouped into 10 clusters based on 22 miRNA levels. The clusters differed in age (χ2 = 19.1, p = 0.024), days post-injury at the time of saliva collection (χ2 = 22.6; p = 0.007), and number of prior concussions (χ2 = 17.6, p = 0.040). The clusters also differed in symptom reports for fatigue (χ2 = 17.7; p = 0.039), confusion (χ2 = 22.3; p = 0.008), difficulty remembering (χ2 = 22.0; p = 0.009), and trouble falling asleep (χ2 = 17.2; p = 0.046), but not objective balance or cognitive performance (p > 0.05). The miRNAs that defined concussion clusters regulate 16 physiological pathways, including adrenergic signaling, estrogen signaling, fatty acid metabolism, GABAergic signaling, synaptic vesicle cycling, and transforming growth factor (TGF)-β signaling. These results show that saliva miRNA levels may stratify individuals with concussion based on underlying biological perturbations that are relevant to both symptomology and pharmacological targets. If validated in a larger cohort, miRNA assessment could aid individualized, biology-driven concussion treatment.

Early Salivary miRNA Expression in Extreme Low Gestational Age Newborns

Background: MicroRNAs (miRNA) are small non-coding RNAs that regulate gene expression playing a key role in organogenesis. MiRNAs are studied in tracheal aspirates (TA) of preterm infants. However; this is difficult to obtain in infants who are not intubated. This study examines early salivary miRNA expression as non-invasive early biomarkers in extremely low gestational age newborns (ELGANs). Methods: Saliva was collected using DNA-genotek swabs, miRNAs were analyzed using RNA seq and RT PCR arrays. Salivary miRNA expression was compared to TA using RNA seq at 3 days of age, and longitudinal changes at 28 days of age were analyzed using RT PCR arrays in ELGANs. Results: Approximately 822 ng of RNA was extracted from saliva of 7 ELGANs; Of the 757 miRNAs isolated, 161 miRNAs had significant correlation in saliva and TA at 3 days of age (r = 0.97). Longitudinal miRNA analysis showed 29 miRNAs downregulated and 394 miRNAs upregulated at 28 days compared to 3 days of age (adjusted p < 0.1). Bioinformatic analysis (Ingenuity Pathway Analysis) of differentially expressed miRNAs identified organismal injury and abnormalities and cellular development as the top physiological system development and cellular function. Conclusion: Salivary miRNA expression are source for early biomarkers of underlying pathophysiology in ELGANs.

Salivary S100 calcium-binding protein beta (S100B) and neurofilament light (NfL) after acute exposure to repeated head impacts in collegiate water polo players

Blood-based biomarkers of brain injury may be useful for monitoring brain health in athletes at risk for concussions. Two putative biomarkers of sport-related concussion, neurofilament light (NfL), an axonal structural protein, and S100 calcium-binding protein beta (S100B), an astrocyte-derived protein, were measured in saliva, a biofluid which can be sampled in an athletic setting without the risks and burdens associated with blood sampled by venipuncture. Samples were collected from men’s and women’s collegiate water polo players (n = 65) before and after a competitive tournament. Head impacts were measured using sensors previously evaluated for use in water polo, and video recordings were independently reviewed for the purpose of validating impacts recorded by the sensors. Athletes sustained a total of 107 head impacts, all of which were asymptomatic (i.e., no athlete was diagnosed with a concussion or more serious). Post-tournament salivary NfL was directly associated with head impact frequency (RR = 1.151, p = 0.025) and cumulative head impact magnitude (RR = 1.008, p = 0.014), while controlling for baseline salivary NfL. Change in S100B was not associated with head impact exposure (RR < 1.001, p > 0.483). These patterns suggest that repeated head impacts may cause axonal injury, even in asymptomatic athletes.

Salivary Biomarkers as Indicators of TBI Diagnosis and Prognosis: A Systematic Review

BACKGROUND AND OBJECTIVE

Traumatic brain injuries are physical injuries to the head that result in disruptions to normal brain function. Diagnostic tools such as computed tomography scans have commonly been used to detect traumatic brain injuries but are costly and not ubiquitously available. Recent research on diagnostic alternatives has focused on using salivary biomarkers, but there is no consensus on the utility of these methods.  The objective of this manuscript is to address the gap in the literature pertaining to the effectiveness of salivary biomarkers for TBI diagnosis and prognosis.

METHODS

A systematic review was conducted between November 2020 and October 2021 using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Six databases were searched using the terms "traumatic brain injury," "TBI," "saliva," and "biomarkers." Literature published prior to 2010 was excluded, and two authors reviewed each full-text article to ensure its relevance.

RESULTS

A total of 18 articles were included in this review, with nine articles on salivary microRNA, three on salivary hormones, three on salivary extracellular vesicles, and three on salivary proteins.

CONCLUSIONS

Studies reported changes in salivary biomarkers after traumatic brain injuries and indicated a possible link between salivary biomarker expression and traumatic brain injury severity. However, it is unclear the degree to which salivary biomarkers accurately predict traumatic brain injury diagnosis and prognosis; some studies reported significant associations while others reported weaker associations. More research into the robustness of salivary biomarkers is needed to fully elucidate their utility for the traumatic brain injury population.

Clues for Improving the Pathophysiology Knowledge for Endometriosis Using Plasma Micro-RNA Expression

The pathophysiology of endometriosis remains poorly understood. The aim of the present study was to investigate functions and pathways associated with the various miRNAs differentially expressed in patients with endometriosis. Plasma samples of the 200 patients from the prospective "ENDO-miRNA" study were analyzed and all known human miRNAs were sequenced. For each miRNA, sensitivity, specificity, and ROC AUC values were calculated for the diagnosis of endometriosis. miRNAs with an AUC ≥ 0.6 were selected for further analysis. A comprehensive review of recent articles from the PubMed, Clinical Trials.gov, Cochrane Library, and Web of Science databases was performed to identify functions and pathways associated with the selected miRNAs. In total, 2633 miRNAs were found in the patients with endometriosis. Among the 57 miRNAs with an AUC ≥ 0.6: 20 had never been reported before; one (miR-124-3p) had previously been observed in endometriosis; and the remaining 36 had been reported in benign and malignant disorders. miR-124-3p is involved in ectopic endometrial cell proliferation and invasion and plays a role in the following pathways: mTOR, STAT3, PI3K/Akt, NF-κB, ERK, PLGF-ROS, FGF2-FGFR, MAPK, GSK3B/β-catenin. Most of the remaining 36 miRNAs are involved in carcinogenesis through cell proliferation, apoptosis, and invasion. The three main pathways involved are Wnt/β-catenin, PI3K/Akt, and NF-KB. Our results provide evidence of the relation between the miRNA profiles of patients with endometriosis and various signaling pathways implicated in its pathophysiology.

Pre-symptomatic intervention for autism spectrum disorder (ASD): defining a research agenda

Autism spectrum disorder (ASD) impacts an individual's ability to socialize, communicate, and interact with, and adapt to, the environment. Over the last two decades, research has focused on early identification of ASD with significant progress being made in understanding the early behavioral and biological markers that precede a diagnosis, providing a catalyst for pre-symptomatic identification and intervention. Evidence from preclinical trials suggest that intervention prior to the onset of ASD symptoms may yield more improved developmental outcomes, and clinical studies suggest that the earlier intervention is administered, the better the outcomes. This article brings together a multidisciplinary group of experts to develop a conceptual framework for behavioral intervention, during the pre-symptomatic period prior to the consolidation of symptoms into diagnosis, in infants at very-high-likelihood for developing ASD (VHL-ASD). The overarching goals of this paper are to promote the development of new intervention approaches, empirical research, and policy efforts aimed at VHL-ASD infants during the pre-symptomatic period (i.e., prior to the consolidation of the defining features of ASD).

Quick cell-free DNA testing for the prediction of postconcussion syndrome: a single-center prospective pilot trial

OBJECTIVE

Mild traumatic brain injury (mTBI) is a major cause of emergency room (ER) admission. Thirty percent of mTBI patients have postconcussion syndrome (PCS), and 15% have symptoms for over a year. This population is underdiagnosed and does not receive appropriate care. The authors proposed a fast and inexpensive fluorometric measurement of circulating cell-free DNA (cfDNA) as a biomarker for PCS. cfDNA is a proven, useful marker of a variety of acute pathological conditions such as trauma and acute illness.

METHODS

Thirty mTBI patients were recruited for this prospective single-center trial. At admission, patients completed questionnaires and blood was drawn to obtain cfDNA. At 3-4 months after injury, 18 patients returned for cognitive assessments with questionnaires and the Color Trails Test (CTT). The fast SYBR Gold assay was used to measure cfDNA.

RESULTS

Seventeen men and 13 women participated in this trial. The mean ± SD age was 50.9 ± 13.9 years. Of the 18 patients who returned for cognitive assessment, one-third reported working fewer hours, 4 (22.2%) changed their driving patterns, and 5 (27.7%) reduced or stopped performing physical activity. The median cfDNA level of the mTBI group was greater than that of the matched healthy control group (730.5 vs 521.5 ng/ml, p = 0.0395). Admission cfDNA concentration was negatively correlated with performance on the CTT1 and CTT2 standardized tests (r = -0.559 and -0.599), meaning that greater cfDNA level was correlated with decreased cognitive performance status. The performance of the patients with normal cfDNA level included in the mTBI group was similar to that of the healthy participants. In contrast, the increased cfDNA group (> 800 ng/ml) had lower scores on the CTT tests than the normal cfDNA group (p < 0.001). Furthermore, patients with moderate/severe cognitive impairment according to CTT1 results had a greater median cfDNA level than the patients with scores indicating mild impairment or normal function (1186 vs 473.5 ng/ml, p = 0.0441, area under the receiver operating characteristic curve = 0.8393).

CONCLUSIONS

The data from this pilot study show the potential to use cfDNA, as measured with a fast test, as a biomarker to screen for PCS in the ER. A large-scale study is required to establish the value of cfDNA as an early predictor of PCS.

Unique diagnostic signatures of concussion in the saliva of male athletes: the Study of Concussion in Rugby Union through MicroRNAs (SCRUM)

Objective

To investigate the role of salivary small non-coding RNAs (sncRNAs) in the diagnosis of sport-related concussion.

Methods

Saliva was obtained from male professional players in the top two tiers of England’s elite rugby union competition across two seasons (2017–2019). Samples were collected preseason from 1028 players, and during standardised head injury assessments (HIAs) at three time points (in-game, post-game, and 36–48 hours post-game) from 156 of these. Samples were also collected from controls (102 uninjured players and 66 players sustaining a musculoskeletal injury). Diagnostic sncRNAs were identified with next generation sequencing and validated using quantitative PCR in 702 samples. A predictive logistic regression model was built on 2017–2018 data (training dataset) and prospectively validated the following season (test dataset).

Results

The HIA process confirmed concussion in 106 players (HIA+) and excluded this in 50 (HIA−). 32 sncRNAs were significantly differentially expressed across these two groups, with let-7f-5p showing the highest area under the curve (AUC) at 36–48 hours. Additionally, a combined panel of 14 sncRNAs (let-7a-5p, miR-143-3p, miR-103a-3p, miR-34b-3p, RNU6-7, RNU6-45, Snora57, snoU13.120, tRNA18Arg-CCT, U6-168, U6-428, U6-1249, Uco22cjg1, YRNA_255) could differentiate concussed subjects from all other groups, including players who were HIA− and controls, immediately after the game (AUC 0.91, 95% CI 0.81 to 1) and 36–48 hours later (AUC 0.94, 95% CI 0.86 to 1). When prospectively tested, the panel confirmed high predictive accuracy (AUC 0.96, 95% CI 0.92 to 1 post-game and AUC 0.93, 95% CI 0.86 to 1 at 36–48 hours).

Conclusions

SCRUM, a large prospective observational study of non-invasive concussion biomarkers, has identified unique signatures of concussion in saliva of male athletes diagnosed with concussion.

Saliva RNA biomarkers predict concussion duration and detect symptom recovery: a comparison with balance and cognitive testing

OBJECTIVE

The goals of this study were to assess the ability of salivary non-coding RNA (ncRNA) levels to predict post-concussion symptoms lasting ≥ 21 days, and to examine the ability of ncRNAs to identify recovery compared to cognition and balance.

METHODS

RNA sequencing was performed on 505 saliva samples obtained longitudinally from 112 individuals (8-24-years-old) with mild traumatic brain injury (mTBI). Initial samples were obtained ≤ 14 days post-injury, and follow-up samples were obtained ≥ 21 days post-injury. Computerized balance and cognitive test performance were assessed at initial and follow-up time-points. Machine learning was used to define: (1) a model employing initial ncRNA levels to predict persistent post-concussion symptoms (PPCS) ≥ 21 days post-injury; and (2) a model employing follow-up ncRNA levels to identify symptom recovery. Performance of the models was compared against a validated clinical prediction rule, and balance/cognitive test performance, respectively.

RESULTS

An algorithm using age and 16 ncRNAs predicted PPCS with greater accuracy than the validated clinical tool and demonstrated additive combined utility (area under the curve (AUC) 0.86; 95% CI 0.84-0.88). Initial balance and cognitive test performance did not differ between PPCS and non-PPCS groups (p > 0.05). Follow-up balance and cognitive test performance identified symptom recovery with similar accuracy to a model using 11 ncRNAs and age. A combined model (ncRNAs, balance, cognition) most accurately identified recovery (AUC 0.86; 95% CI 0.83-0.89).

CONCLUSIONS

ncRNA biomarkers show promise for tracking recovery from mTBI, and for predicting who will have prolonged symptoms. They could provide accurate expectations for recovery, stratify need for intervention, and guide safe return-to-activities.