National Institute of Neurological Disorders and Stroke Consensus Diagnostic Criteria for Traumatic Encephalopathy Syndrome

The neuropathology of chronic traumatic encephalopathy

Chronic traumatic encephalopathy (CTE) is a progressive tauopathy causally linked to repetitive mild traumatic brain injury. Currently, there are no established clinical diagnostic criteria for CTE, making post-mortem neuropathological examination essential for diagnosis. The pathological hallmark of CTE is the presence of perivascular neuronal p-tau aggregates at cortical sulcal depths. In this commentary, we share our diagnostic experience, highlight emerging diagnostic protocols for CTE, and discuss the challenges in CTE diagnosis and its differentiation from comorbid conditions. Beyond the neuropathological insights, we explore the broader implications of CTE for the community, including the need for prevention strategies and the role of public health policy. By advancing understanding of CTE pathology, neuropathologists are positioned to inform prevention and treatment efforts, ultimately contributing to the mitigation of this preventable disease.

Dispersion-based cognitive intra-individual variability in former American football players: Association with traumatic encephalopathy syndrome, repetitive head impacts, and biomarkers

Background: Exposure to repetitive head impacts (RHI), such as those experienced in American football, is linked to cognitive dysfunction later in life. Traumatic encephalopathy syndrome (TES) is a proposed clinical syndrome thought to be linked to neuropath-ology of chronic traumatic encephalopathy (CTE), a condition associated with RHI from football. Cognitive intra-individual variability (d-CIIV) measures test-score dispersion, indicating cognitive dysfunction. This study examined d-CIIV in former football players and its associations with TES diagnosis, RHI exposure, and DTI and CSF biomarkers. Methods: Data included 237 males (45-74 years) from DIAGNOSE CTE Research Project, including former professional and college football players (COL) (n = 173) and asymptomatic men without RHI or TBI (n = 55). Participants completed neuropsychological tests. TES diagnosis was based on 2021 NINDS TES criteria. Years of football play and a cumulative head impact index (CHII) measured RHI exposure. Lumipulse technology was used for CSF assays. DTI fractional anisotropy assessed white matter integrity. Coefficient of variation (CoV) measured d-CIIV. ANCOVA compared d-CIIV among groups (football versus control; TES-status). Pearson correlations and linear regressions tested associations between d-CIIV, RHI exposure, and CSF and DTI biomarkers. Results: Former professional players had higher d-CIIV than controls (F(7, 194) = 2.87, p = .007). d-CIIV was associated with TES diagnosis (F(8, 146) = 9.063, p < .001), with highest d-CIIV in TES Possible/Probable-CTE. Higher d-CIIV correlated with higher CHII scores (r = 0.19), reduced CSF Aβ1-42 (β = -0.302), increased p-tau181 (β = 0.374), and reduced DTI FA (β = -0.202). Conclusion: d-CIIV is linked to RHI exposure and TES diagnosis in former football players, with associated changes in CSF biomarkers and white matter integrity.

Single- versus two-test criteria for cognitive impairment: associations with CSF and imaging markers in former American football players

Objective: Cognitive impairment is a core feature of traumatic encephalopathy syndrome (TES), the putative clinical syndrome of chronic traumatic encephalopathy-a neuropathological disease associated with repetitive head impacts (RHI). Careful operationalization of cognitive impairment is essential to improving the diagnostic specificity and accuracy of TES criteria. We compared single- versus two-test criteria for cognitive impairment in their associations with CSF and imaging biomarkers in male former American football players. Method: 169 participants from the DIAGNOSE CTE Research Project completed neuropsychological tests of memory and executive functioning. Cognitive impairment was identified by single-test criteria (z≤-1.5 on one test) and two-test criteria (z<-1 on two tests within a domain). ANCOVAs adjusting for age, race, education, body mass index, word-reading score, and APOE ε4 status assessed whether single- or two-test criteria predicted CSF markers (Aβ1-42, p-tau181, p-tau181/Aβ1-42, total tau, neurofilament light [NfL], glial fibrillary acidic protein [GFAP]) and MRI markers (hippocampal volume, cortical thickness, white matter hyperintensities). Results: Ninety-nine participants met single-test criteria for cognitive impairment. Sixty-six met two-test criteria. Participants who met two-test criteria had greater exposure to RHI than those who did not (p=.04). Two-test criteria were -associated with higher CSF p-tau181/Aβ1-42 (q=.02) and CSF NfL (q=.02). The association between two-test criteria and CSF NfL remained after excluding amyloid-positive participants (q=.04). Single-test criteria were not associated with any biomarkers (q's>.05). Conclusions: Two-test but not single-test criteria for cognitive impairment were associated with markers of neurodegeneration. Future clinical research in TES may benefit from applying two-test criteria to operationalize cognitive impairment.

Chronic traumatic encephalopathy: State-of-the-science update and narrative review

OBJECTIVE

The long-recognized association of brain injury with increased risk of dementia has undergone significant refinement and more detailed study in recent decades. Chronic traumatic encephalopathy (CTE) is a specific neurodegenerative tauopathy related to prior exposure to repetitive head impacts (RHI). We aim to contextualize CTE within a historical perspective and among emerging data which highlights the scientific and conceptual evolution of CTE-related research in parallel with the broader field of neurodegenerative disease and dementia.

METHODS

We provide a narrative state-of-the-science update on CTE neuropathology, clinical manifestations, biomarkers, different types and patterns of head impact exposure relevant for CTE, and the complicated influence of neurodegenerative co-pathology on symptoms.

CONCLUSIONS

Now almost 20 years since the initial case report of CTE in a former American football player, the field of CTE continues evolving with increasing clarity but also several ongoing controversies. Our understanding of CTE neuropathology outpaces that of disease-specific clinical correlates or the development of in-vivo biomarkers. Diagnostic criteria for symptoms attributable to CTE are still being validated, but leveraging increasingly available biomarkers for other conditions like Alzheimer's disease may be helpful for informing the CTE differential diagnosis. As diagnostic refinement efforts advance, clinicians should provide care and/or referrals to providers best suited to treat an individual patient's clinical symptoms, many of which have evidence-based behavioral treatment options that are etiologically agnostic. Several ongoing research initiatives and the gradual accrual of gold standard clinico-pathological data will pay dividends for advancing the many existing gaps in the field of CTE.

Poor long-term outcomes and abnormal neurodegeneration biomarkers after military traumatic brain injury: the ADVANCE study

BACKGROUND

Traumatic brain injury (TBI) is common in military campaigns and is a risk factor for dementia. ArmeD SerVices TrAuma and RehabilitatioN OutComE-TBI (ADVANCE-TBI) aims to ascertain neurological outcomes in UK military personnel with major battlefield trauma, leveraging advances in quantification of axonal breakdown markers like neurofilament light (NfL), and astroglial marker glial fibrillar acidic protein (GFAP) in blood. We aimed to describe the causes, prevalence and consequences of TBI, and its fluid biomarker associations.

METHODS

TBI history was ascertained in 1145 servicemen and veterans, of whom 579 had been exposed to major trauma. Functional and mental health assessments were administered, and blood samples were collected approximately 8 years postinjury, with plasma biomarkers quantified (n=1125) for NfL, GFAP, total tau, phospho-tau181, amyloid-β 42 and 40. Outcomes were related to neurotrauma exposure.

RESULTS

TBI was present in 16.9% (n=98) of exposed participants, with 46.9% classified as mild-probable and 53.1% classified as moderate to severe. Depression (β=1.65, 95% CI (1.33 to 2.03)), anxiety (β=1.65 (1.34 to 2.03)) and post-traumatic stress disorder (β=1.30 (1.19 to 1.41)) symptoms were more common after TBI, alongside poorer 6 minute walk distance (β=0.79 (0.74 to 0.84)) and quality of life (β=1.27 (1.19 to 1.36), all p<0.001). Plasma GFAP was 11% (95% CI 2 to 21) higher post-TBI (p=0.013), with greater concentrations in moderate-to-severe injuries (47% higher than mild-probable (95% CI 20% to 82%, p<0.001). Unemployment was more common among those with elevated GFAP levels post-TBI, showing a 1.14-fold increase (95% CI 1.03 to 1.27, p<0.001) for every doubling in GFAP concentration.

CONCLUSIONS

TBI affected nearly a fifth of trauma-exposed personnel, related to worse mental health, motor and functional outcomes, as well as elevated plasma GFAP levels 8 years post-injury. This was absent after extracranial trauma, and showed a dose-response relationship with the severity of the injury.

Age of First Exposure to Contact Sports Is Not Associated With Worse Later-In-Life Brain Health in a Cohort of Community-Dwelling Older Men

OBJECTIVE

To evaluate whether early age of first exposure to contact sports (AFE-CS) is associated with worse long-term brain health outcomes.

DESIGN

A cross-sectional, survey study of older men with a history of contact sport participation was completed.

SETTING

Tertiary care facility.

PARTICIPANTS

A cohort of community-dwelling older men dichotomized by using AFE-CS (<12 years vs ≥12 years).

INTERVENTIONS

Independent variables included a dichotomized group of AFE-CS (<12 years vs ≥12 years).

MAIN OUTCOME MEASURES

Brain health outcomes measured by depression, anxiety, cognitive difficulties, and neurobehavioral symptoms. Endorsements of general health problems, motor symptoms, and psychiatric history were also collected. Age of first exposure groups was compared using t tests, χ 2 tests, and multivariable linear regressions, which included the following covariates: age, number of prior concussions, and total years of contact sport.

RESULTS

Of 69 men aged 70.5 ± 8.0 years, approximately one-third of the sample (34.8%) reported AFE-CS before age 12 years. That group had more years of contact sports (10.8 ± 9.2 years) compared with those with AFE-CS ≥12 (5.6 ± 4.5 years; P = 0.02). No differences were found after univariate testing between AFE-CS groups on all outcomes ( P -values >0.05). Multivariable models suggest that AFE-CS is not a predictor of depression or anxiety. Those in the AFE-CS <12 group had fewer cognitive difficulties ( P = 0.03) and fewer neurobehavioral symptoms ( P = 0.03).

CONCLUSIONS

Those with AFE-CS <12 to contact sports did not have worse long-term brain health outcomes compared with those with AFE-CS ≥12. Individuals with AFE-CS <12 had significantly lower British Columbia Cognitive Complaints Inventory and Neurobehavioral Symptom Inventory scores compared with those with AFE-CS ≥12.

CLINICAL RELEVANCE

The benefits of earlier AFE-CS may outweigh the risks of head strikes and result in comparable long-term brain health outcomes.

Five-Year Serial Brain MRI Analysis of Military Members Exposed to Chronic Sub-Concussive Overpressures

BACKGROUND

The Canadian Special Operations Forces Command conducts explosives operations and training which exposes members to explosive charges at close proximity. This 5-year longitudinal trial was conducted in follow-up to our initial trial which examined military breachers with MRI and EEG pre and post blast exposure.

PURPOSE

To examine brain MRI findings in military personnel exposed to multiple repeated blast exposures.

STUDY TYPE

Five-year longitudinal prospective trial.

POPULATION

Ninety-two males aged 23-42 with an average of 9.4 years of blast exposure.

FIELD STRENGTH/SEQUENCE

3 T brain MRI/T1-weighted 3D with reconstruction in three planes, T2-weighted, T2-weighted fluid attenuated inversion recovery (FLAIR) 3D with reconstruction in three planes, T2-weighted gradient spin echo (GRE), saturation weighted images, DWI and ADC maps, diffusion tensor imaging.

ASSESSMENT

All MRI scans were interpreted by the two neuroradiologists and one neuroradiology Fellow in a blinded fashion using a customized neuroradiology reporting form.

STATISTICAL TESTS

Matching parametric statistics represented the number of participants whose brain parameters improved or deteriorated over time. Odds ratio (OR) and 95% confidence intervals (CI) were computed using log regression modeling to determine volume loss, white matter lesions, hemosiderosis, gliosis, cystic changes and enlarged Virchow Robin (VR) spaces. A Kappa (κ) statistic with a 95% CI was calculated to determine rater variability between readers.

RESULTS

A significant deterioration was observed in volume loss (OR = 1.083, 95% CI 0.678-1.731, permutation test), white matter changes (OR: 0.754, 95% CI 0.442-1.284, permutation test), and enlargement of VR spaces (OR: 0.775, 95% CI 0.513-1.171). Interrater reliability was low: κ = 0.283, 0.156, and 0.557 for volume loss, white matter changes, and enlargement of VR spaces, respectively.

DATA CONCLUSION

There were significant changes in brain volume, white matter lesions, and enlargement of VR spaces.

EVIDENCE LEVEL

2 TECHNICAL EFFICACY: Stage 2.

Chronic Traumatic Encephalopathy, Family History of Mental Illness, and Aggression in Brain Donors With Repetitive Head Impact Exposure

BACKGROUND AND OBJECTIVES

Chronic traumatic encephalopathy (CTE) is a neurodegenerative tauopathy associated with exposure to repetitive head impacts, including from contact sports and military service. Although CTE case reports have commonly described aggression during midlife, recent studies failed to show associations between CTE tau burden and aggression. First-degree family history of mental illness (1°FHMI) is a well-established risk factor of aggression. We tested the hypothesis that CTE pathology moderates the association between 1°FHMI and aggression, providing an explanation for the lack of association previously observed.

METHODS

This was a retrospective examination of consecutive, deceased, male brain donors with repetitive head impact exposure from the Understanding Neurologic Injury and Traumatic Encephalopathy Study at Boston University from 2014 to 2021. Neuropathologists diagnosed CTE using established National Institute of Neurological Disorders and Stroke criteria. Informants were administered the Brown-Goodwin Assessment for Lifetime History of Aggression (BGLHA) and were queried regarding 1°FHMI. Exploratory factor analysis evaluated BGLHA factor structure. Stratified by CTE status, linear regression analyses examined relationships between 1°FHMI and standardized adult BGLHA scores and factor scores. Models were adjusted for race, age at death, education, years of contact sport play, military history, substance use treatment history, psychologically traumatic event history, and BGLHA childhood score.

RESULTS

Among 845 brain donors, the mean age at death was 60.3 (SD = 19.6) years. 589 donors (69.7%) had CTE, and 383 donors (45.3%) had a 1°FHMI. 1°FHMI was significantly associated with standardized adult BGLHA scores in those with CTE, but not in those without CTE (CTE present: β = 0.16, 95% CI 0.02-0.29; CTE absent: β = 0.10, 95% CI -0.12 to 0.32). The largest effects were observed among those with CTE, aged 40-59 years (CTE present: β = 0.64, 95% CI 0.32-0.96; CTE absent: β = 0.05, 95% CI -0.44 to 0.54), particularly for BGLHA factors of emotional dysregulation/impulsiveness (CTE present: β = 1.68, 95% CI 0.78-2.58; CTE absent: β = 0.09, 95% CI -1.20 to 1.37) and antisocial behavior (CTE present: β = 1.56, 95% CI 0.64-2.47; CTE absent: β = 0.10, 95% CI -1.19 to 1.40).

DISCUSSION

Among brain donors exposed to repetitive head impacts, CTE pathology moderated the effect of 1°FHMI on BGLHA scores, with the largest effects in midlife. Predisposition to mental illness and CTE pathology may increase risk of aggression beyond each risk factor's additive effects. Prospective studies are needed to confirm these results.

Alzheimer's Association clinical practice guideline for the Diagnostic Evaluation, Testing, Counseling, and Disclosure of Suspected Alzheimer's Disease and Related Disorders (DETeCD-ADRD): Executive summary of recommendations for primary care

US clinical practice guidelines for the diagnostic evaluation of cognitive impairment due to Alzheimer's disease (AD) or AD and related dementias (ADRD) are decades old and aimed at specialists. This evidence-based guideline was developed to empower all-including primary care-clinicians to implement a structured approach for evaluating a patient with symptoms that may represent clinical AD/ADRD. Through a modified-Delphi approach and guideline-development process (7374 publications were reviewed; 133 met inclusion criteria) an expert workgroup developed recommendations as steps in a patient-centered evaluation process. This summary focuses on recommendations, appropriate for any practice setting, forming core elements of a high-quality, evidence-supported evaluation process aimed at characterizing, diagnosing, and disclosing the patient's cognitive functional status, cognitive-behavioral syndrome, and likely underlying brain disease so that optimal care plans to maximize patient/care partner dyad quality of life can be developed; a companion article summarizes specialist recommendations. If clinicians use this guideline and health-care systems provide adequate resources, outcomes should improve in most patients in most practice settings. Highlights US clinical practice guidelines for the diagnostic evaluation of cognitive impairment due to Alzheimer's disease (AD) or AD and related dementias (ADRD) are decades old and aimed at specialists. This evidence-based guideline was developed to empower all-including primary care-clinicians to implement a structured approach for evaluating a patient with symptoms that may represent clinical AD/ADRD. This summary focuses on recommendations, appropriate for any practice setting, forming core elements of a high-quality, evidence-supported evaluation process aimed at characterizing, diagnosing, and disclosing the patient's cognitive functional status, cognitive-behavioral syndrome, and likely underlying brain disease so that optimal care plans to maximize patient/care partner dyad quality of life can be developed; a companion article summarizes specialist recommendations. If clinicians use this guideline and health-care systems provide adequate resources, outcomes should improve in most patients in most practice settings.

Traumatic Brain Injury and Risk of Incident Dementia: Forensic Applications of Current Research

OBJECTIVE

Traumatic Brain Injury (TBI) has been identified as a risk factor for later developing neurodegenerative disorders, and there has been significant attention on this association in forensic settings. As a result, forensic neuropsychologists are frequently asked to comment on risk for dementia after an alleged TBI in litigation and criminal cases. This article provides an evidence-based foundation to aid forensic practice by synthesizing comprehensive information pertaining to: (i) the role of the neuropsychologist in TBI-related litigation, (ii) the complexities associated with identifying TBIs in forensic cases, (iii) the science of TBI in relation to incident dementia, and (iv) current scientific evidence for chronic traumatic encephalopathy.

RESULTS

Developing a neurodegenerative disorder after TBI is the exception rather than the rule. Prevalence rates suggest that only a small subset (< 5%) of individuals with moderate-to-severe TBI, and even fewer (< 1%) with mild TBI (mTBI), appear to develop certain neurodegenerative diseases, and the characteristics that place some at risk remain unclear. The literature is mixed in terms of identifying a relationship between mTBI and later-in-life dementia risk. Also, the quality of positive evidence for risk of dementia after mTBI is weak and mostly consists of observational studies characterized by methodological limitations.

CONCLUSIONS

Methods used to establish the likely occurrence of a TBI in a forensic context are typically more extensive than those used in a routine clinical evaluation. Research methodology to define TBI is often even more rudimentary and inconsistent. Applying clinical research results of TBI and dementia outcomes to forensic cases at an individual level carries significant limitations. Estimating the contribution of remote head hits or concussion in a causal manner to dementia is a challenge forensic experts sometimes face, yet at present, the task is impossible beyond correlations and speculation.

Fluid biomarkers of chronic traumatic brain injury

Traumatic brain injury (TBI) is a leading cause of long-term disability across the world. Evidence for the usefulness of imaging and fluid biomarkers to predict outcomes and screen for the need to monitor complications in the acute stage is steadily increasing. Still, many people experience symptoms such as fatigue and cognitive and motor dysfunction in the chronic phase of TBI, where objective assessments for brain injury are lacking. Consensus criteria for traumatic encephalopathy syndrome, a clinical syndrome possibly associated with the neurodegenerative disease chronic traumatic encephalopathy, which is commonly associated with sports concussion, have been defined only recently. However, these criteria do not fit all individuals living with chronic consequences of TBI. The pathophysiology of chronic TBI shares many similarities with other neurodegenerative and neuroinflammatory conditions, such as Alzheimer disease. As with Alzheimer disease, advancements in fluid biomarkers represent one of the most promising paths for unravelling the chain of pathophysiological events to enable discrimination between these conditions and, with time, provide prediction modelling and therapeutic end points. This Review summarizes fluid biomarker findings in the chronic phase of TBI (≥6 months after injury) that demonstrate the involvement of inflammation, glial biology and neurodegeneration in the long-term complications of TBI. We explore how the biomarkers associate with outcome and imaging findings and aim to establish mechanistic differences in biomarker patterns between types of chronic TBI and other neurodegenerative conditions. Finally, current limitations and areas of priority for future fluid biomarker research are highlighted.

Examination of plasma biomarkers of amyloid, tau, neurodegeneration, and neuroinflammation in former elite American football players

INTRODUCTION

Blood-based biomarkers offer a promising approach for the detection of neuropathologies from repetitive head impacts (RHI). We evaluated plasma biomarkers of amyloid, tau, neurodegeneration, and inflammation in former football players.

METHODS

The sample included 180 former football players and 60 asymptomatic, unexposed male participants (aged 45-74). Plasma assays were conducted for beta-amyloid (Aβ) 40, Aβ42, hyper-phosphorylated tau (p-tau) 181+231, total tau (t-tau), neurofilament light (NfL), glial fibrillary acidic protein (GFAP), interleukin-6 (IL-6), Aβ42/p-tau181 and Aβ42/Aβ40 ratios. We evaluated their ability to differentiate the groups and associations with RHI proxies and traumatic encephalopathy syndrome (TES).

RESULTS

P-tau181 and p-tau231(padj = 0.016) were higher and Aβ42/p-tau181 was lower(padj = 0.004) in football players compared to controls. Discrimination accuracy for p-tau was modest (area under the curve [AUC] = 0.742). Effects were not attributable to AD-related pathology. Younger age of first exposure (AFE) correlated with higher NfL (padj = 0.03) and GFAP (padj = 0.033). Plasma GFAP was higher in TES-chronic traumatic encephalopathy (TES-CTE) Possible/Probable (padj = 0.008).

DISCUSSION

Plasma p-tau181 and p-tau231, GFAP, and NfL may offer some usefulness for the characterization of RHI-related neuropathologies.

HIGHLIGHTS

Former football players had higher plasma p-tau181 and p-tau231 and lower Aβ42/ptau-181 compared to asymptomatic, unexposed men. Younger age of first exposure was associated with increased plasma NfL and GFAP in older but not younger participants. Plasma GFAP was higher in participants with TES-CTE possible/probable compared to TES-CTE no/suggestive.

A bibliometric analysis of the relationship between traumatic brain injury and Alzheimer's disease (1993-2023)

Background

Traumatic brain injury (TBI) increases the risk of developing Alzheimer's disease (AD), and a growing number of studies support a potential link between the two disorders. Therefore, the objective of this study is to systematically map the knowledge structure surrounding this topic over the past and to summarize the current state of research and hot frontiers in the field.

Methods

Data were retrieved from the Web of Science Core Collection (WOSCC) starting from the beginning until December 31, 2023, focusing on articles and reviews in English. Bibliometric tools including Bibliometrix R, VOSviewer, and Microsoft Excel were utilized for data analysis. The analysis included citations, authors, institutions, countries, journals, author keywords, and references.

Results

A total of 1,515 publications were identified, comprising 872 articles (57.56%) and 643 reviews (42.44%). The annual number of publications increased steadily, especially after 2013, with an R2 value of 0.978 indicating a strong upward trend. The USA was the leading country in terms of publications (734 articles), followed by China (162 articles) and the United Kingdom (77 articles). Meanwhile Boston University was the most productive institution. Collaborative networks show strong collaborative author links between the USA and the United Kingdom, as well as China. The analysis also showed that the Journal of Alzheimer's Disease was the most productive journal, while the article authored by McKee achieved the highest local citations value. The top three author keywords, in terms of occurrences, were "Alzheimer's disease," "traumatic brain injury," and "neurodegeneration." Thematic mapping showed a consolidation of research themes over time, decreasing from 11 main themes to 8. Emerging themes such as "obesity" and "diffusion tensor imaging" indicate new directions in the field.

Conclusion

The research on AD after TBI has attracted a great deal of interest from scientists. Notably, the USA is at the forefront of research in this field. There is a need for further collaborative research between countries. Overall, this study provides a comprehensive overview of developments in TBI and AD research, highlighting key contributors, emerging topics, and potential areas for future investigation.

Repetitive subconcussion results in disrupted neural activity independent of concussion history

Concussion is a public health crisis that results in a complex cascade of neurochemical changes that can have life-changing consequences. Subconcussions are generally considered less serious, but we now realize repetitive subconcussions can lead to serious neurological deficits. Subconcussions are common in contact sports and the military where certain personnel are exposed to repetitive occupational blast overpressure. Post-mortem studies show subconcussion is a better predictor than concussion for chronic traumatic encephalopathy-a progressive and fatal neurodegenerative tauopathy, only diagnosable post-mortem-thus, an in vivo biomarker would be transformative. Magnetoencephalography captures the dynamics of neuronal electrochemical action, and functional MRI shows that functional connectivity is associated with tauopathy patterns. Therefore, both imaging modalities could provide surrogate markers of tauopathy. In this cross-sectional study, we examined the effects of repetitive subconcussion on neuronal activity and functional connectivity using magnetoencephalography and functional MRI, and on neurological symptoms and mental health in a military sample. For magnetoencephalography and outcome analyses, 81 participants were split into 'high' and 'low' blast exposure groups using the generalized blast exposure value: n = 41 high blast (26.4-65.7 years; 4 females) and n = 40 low blast (28.0-63.3 years; 8 females). For functional MRI, two high blast male participants without data were excluded: n = 39 (29.6-65.7 years). Magnetoencephalography revealed disrupted neuronal activity in participants with a greater history of repetitive subconcussions, including neural slowing (higher delta activity) in right fronto-temporal lobes and subcortical regions (hippocampus, amygdala, caudate, pallidum and thalamus), and functional dysconnectivity in the posterior default mode network (lower connectivity at low and high gamma). These abnormalities were independent of concussion or traumatic stress history, and magnetoencephalography showed functional dysconnectivity not detected in functional MRI. Besides magnetoencephalography changes, those with higher blast exposure had poorer somatic and cognitive outcomes, with no blast-related differences in mental health or associations between neurological symptoms and neuronal activity. This study suggests that repetitive subconcussions have deleterious effects on brain function and that magnetoencephalography provides an avenue for both treatment targets by identifying affected brain regions and in prevention by identifying those at risk of cumulative subconcussive neurotrauma.

Epileptic seizure prediction via multidimensional transformer and recurrent neural network fusion

BACKGROUND

Epilepsy is a prevalent neurological disorder in which seizures cause recurrent episodes of unconsciousness or muscle convulsions, seriously affecting the patient's work, quality of life, and health and safety. Timely prediction of seizures is critical for patients to take appropriate therapeutic measures. Accurate prediction of seizures remains a challenge due to the complex and variable nature of EEG signals. The study proposes an epileptic seizure model based on a multidimensional Transformer with recurrent neural network(LSTM-GRU) fusion for seizure classification of EEG signals.

METHODOLOGY

Firstly, a short-time Fourier transform was employed in the extraction of time-frequency features from EEG signals. Second, the extracted time-frequency features are learned using the Multidimensional Transformer model. Then, LSTM and GRU are then used for further learning of the time and frequency characteristics of the EEG signals. Next, the output features of LSTM and GRU are spliced and categorized using the gating mechanism. Subsequently, seizure prediction is conducted.

RESULTS

The model was tested on two datasets: the Bonn EEG dataset and the CHB-MIT dataset. On the CHB-MIT dataset, the average sensitivity and average specificity of the model were 98.24% and 97.27%, respectively. On the Bonn dataset, the model obtained about 99% and about 98% accuracy on the binary classification task and the tertiary upper classification task, respectively.

CONCLUSION

The findings of the experimental investigation demonstrate that our model is capable of exploiting the temporal and frequency characteristics present within EEG signals.

Brain morphometry in former American football players: findings from the DIAGNOSE CTE research project

Exposure to repetitive head impacts in contact sports is associated with neurodegenerative disorders including chronic traumatic encephalopathy (CTE), which currently can be diagnosed only at post-mortem. American football players are at higher risk of developing CTE given their exposure to repetitive head impacts. One promising approach for diagnosing CTE in vivo is to explore known neuropathological abnormalities at post-mortem in living individuals using structural MRI. MRI brain morphometry was evaluated in 170 male former American football players ages 45-74 years (n = 114 professional; n = 56 college) and 54 same-age unexposed asymptomatic male controls (n = 54, age range 45-74). Cortical thickness and volume of regions of interest were selected based on established CTE pathology findings and were assessed using FreeSurfer. Group differences and interactions with age and exposure factors were evaluated using a generalized least squares model. A separate logistic regression and independent multinomial model were performed to predict each traumatic encephalopathy syndrome (TES) diagnosis, core clinical features and provisional level of certainty for CTE pathology using brain regions of interest. Former college and professional American football players (combined) showed significant cortical thickness and/or volume reductions compared to unexposed asymptomatic controls in the hippocampus, amygdala, entorhinal cortex, parahippocampal gyrus, insula, temporal pole and superior frontal gyrus. Post hoc analyses identified group-level differences between former professional players and unexposed asymptomatic controls in the hippocampus, amygdala, entorhinal cortex, parahippocampal gyrus, insula and superior frontal gyrus. Former college players showed significant volume reductions in the hippocampus, amygdala and superior frontal gyrus compared to the unexposed asymptomatic controls. We did not observe Age × Group interactions for brain morphometric measures. Interactions between morphometry and exposure measures were limited to a single significant positive association between the age of first exposure to organized tackle football and right insular volume. We found no significant relationship between brain morphometric measures and the TES diagnosis core clinical features and provisional level of certainty for CTE pathology outcomes. These findings suggested that MRI morphometrics detect abnormalities in individuals with a history of repetitive head impact exposure that resemble the anatomic distribution of pathological findings from post-mortem CTE studies. The lack of findings associating MRI measures with exposure metrics (except for one significant relationship) or TES diagnosis and core clinical features suggested that brain morphometry must be complemented by other types of measures to characterize individuals with repetitive head impacts.

Challenges and limitations in meta-analyses of complications in neurosurgery: Systematic review with proposed approach and checklist to mitigate errors and improve the assessment of the real-world experience

Meta-analyses are highly valued in medical science, yet accurately reporting complications in neurosurgical studies remains challenging. Examples include inconsistencies in defining and classifying complications and variations in reporting methods. This lack of reproducibility and comparability, along with other issues related to biases, hinders the ability of meta-analyses to yield significant advancements. This systematic review investigated the challenges and limitations inherent in meta-analyses of complications in neurosurgery. Based on the identified challenges and our group's experience, we developed a practical checklist to mitigate and avoid common errors in meta-analyses of complications in neurosurgery.We searched PubMed, Embase, and Web of Science for studies addressing challenges in assessing complications in neurosurgery. The main findings were qualitatively synthesized to identify common challenges and limitations. The proposed checklist was developed using a modified Delphi technique. Eleven studies were included, uncovering heterogeneity and a lack of standardization regarding the classification of complications in neurosurgery across various authors and institutions. They suggested solutions such as implementing a more uniform classification system. Additionally, the NeuroComp Meta-Analysis Checklist was developed, comprising 23 items divided into 5 domains, with a practical approach and suggestions on how to deal with the challenges when meta-analyzing.We identified numerous challenges and concerns when assessing complications in the neurosurgical field. The NeuroComp Meta-Analysis Checklist incorporated methodologies and approaches we utilized in several previously published meta-analyses. While we acknowledge that the proposal cannot solve all the issues involved in comparing and meta-analyzing complications in neurosurgery, it has the potential to enhance the informativeness of future meta-analyses and help authors mitigate common errors. Ultimately, this tool has the potential to contribute to the advancement of accumulating real-world evidence in neurosurgical science.

Cavum Septum Pellucidum in Former American Football Players: Findings From the DIAGNOSE CTE Research Project

Background and Objectives

Exposure to repetitive head impacts (RHI) is linked to the development of chronic traumatic encephalopathy (CTE), which can only be diagnosed at post-mortem. The presence of a cavum septum pellucidum (CSP) is a common finding in post-mortem studies of confirmed CTE and in neuroimaging studies of individuals exposed to RHI. This study examines CSP in living former American football players, investigating its association with RHI exposure, traumatic encephalopathy syndrome (TES) diagnosis, and provisional levels of certainty for CTE pathology.

Methods

Data from the DIAGNOSE CTE Research Project were used to compare the presence and ratio of CSP in former American football players (n = 175), consisting of former college (n = 58) and former professional players (n = 117), and asymptomatic unexposed controls without RHI exposure (n = 55). We further evaluated potential associations between CSP measures and cumulative head impact index (CHII) measures (frequency, linear acceleration, and rotational force), a TES diagnosis (yes/no), and a provisional level of certainty for CTE pathology (suggestive, possible, and probable).

Results

Former American football players exhibited a higher CSP presence and ratio than unexposed asymptomatic controls. Among player subgroups, professional players showed a greater CSP ratio than former college players and unexposed asymptomatic controls. Among all football players, CHII rotational forces correlated with an increased CSP ratio. No significant associations were found between CSP measures and diagnosis of TES or provisional levels of certainty for CTE pathology.

Discussion

This study confirms previous findings, highlighting a greater prevalence of CSP and a greater CSP ratio in former American football players compared with unexposed asymptomatic controls. In addition, former professional players showed a greater CSP ratio than college players. Moreover, the relationship between estimates of CHII rotational forces and CSP measures suggests that cumulative frequency and strength of rotational forces experienced in football are associated with CSP. However, CSP does not directly correlate with TES diagnosis or provisional levels of certainty for CTE, indicating that it may be a consequence of RHI associated with rotational forces. Further research, especially longitudinal studies, is needed for confirmation and to explore changes over time.

Assessment of Sports Concussion in Female Athletes: A Role for Neuroinformatics?

Over the past decade, the intricacies of sports-related concussions among female athletes have become readily apparent. Traditional clinical methods for diagnosing concussions suffer limitations when applied to female athletes, often failing to capture subtle changes in brain structure and function. Advanced neuroinformatics techniques and machine learning models have become invaluable assets in this endeavor. While these technologies have been extensively employed in understanding concussion in male athletes, there remains a significant gap in our comprehension of their effectiveness for female athletes. With its remarkable data analysis capacity, machine learning offers a promising avenue to bridge this deficit. By harnessing the power of machine learning, researchers can link observed phenotypic neuroimaging data to sex-specific biological mechanisms, unraveling the mysteries of concussions in female athletes. Furthermore, embedding methods within machine learning enable examining brain architecture and its alterations beyond the conventional anatomical reference frame. In turn, allows researchers to gain deeper insights into the dynamics of concussions, treatment responses, and recovery processes. This paper endeavors to address the crucial issue of sex differences in multimodal neuroimaging experimental design and machine learning approaches within female athlete populations, ultimately ensuring that they receive the tailored care they require when facing the challenges of concussions. Through better data integration, feature identification, knowledge representation, validation, etc., neuroinformaticists, are ideally suited to bring clarity, context, and explainabilty to the study of sports-related head injuries in males and in females, and helping to define recovery.

Repetitive head impacts among professional fighters: a pilot study evaluating Traumatic Encephalopathy Syndrome and postural balance

OBJECTIVES

Clinical criteria for Traumatic Encephalopathy Syndrome (ccTES) were developed for research purposes to reflect the clinical symptoms of Chronic Traumatic Encephalopathy (CTE). The aims of this study were to 1) determine whether there was an association between the research diagnosis of TES and impaired postural balance among retired professional fighters, and 2) determine repetitive head impacts (RHI) exposure thresholds among both TES positive and TES negative groups in retired professional fighters when evaluating for balance impairment.

METHODS

This was a pilot study evaluating postural balance among participants of the Professional Athletes Brain Health Study (PABHS). Among the cohort, 57 retired professional fighters met the criteria for inclusion in this study. A generalized linear model with generalized estimating equations was used to compare various balance measures longitudinally between fighters with and without TES.

RESULTS

A significant association was observed between a TES diagnosis and worsening performance on double-leg balance assessments when stratifying by RHI exposure thresholds. Additionally, elevated exposure to RHI was significantly associated with increased odds of developing TES; The odds for TES diagnosis were 563% (95% CI = 113, 1963; p-value = 0.0011) greater among athletes with 32 or more professional fights compared to athletes with less than 32 fights when stratifying by balance measures. Likewise, the odds for TES diagnosis were 43% (95% CI = 10, 102; p-value = 0.0439) greater with worsening double leg stance balance in athletes exposed to 32 or more fights.

CONCLUSION

This pilot study provides preliminary evidence of a relationship between declining postural balance and a TES diagnosis among retired professional fighters with elevated RHI exposure. Further research exploring more complex assessments such as the Functional Gait Assessment may be of benefit to improve clinical understanding of the relationship between TES, RHI, and balance.

Trends of public interest in chronic traumatic encephalopathy (CTE) from 2004 to 2022

CONTEXT

Public interest in sport-related medical conditions is known to be affected by social media and pop cultural coverage. The purpose of this project was to assess the relationship between popular culture concerning chronic traumatic encephalopathy (CTE) and analyze of how often this topic was searched on the internet.

OBJECTIVES

The objective of this study was to investigate deviations in public interest following player incidents of CTE and the effects that the media has had on public interest in CTE.

METHODS

To determine our primary objective, we utilized Google Trends to extract the monthly relative search interest (RSI) in CTE between January 2002 and October 2022. To assess the increase in RSI following a major event, an autoregressive integrated moving average (ARIMA) to predict RSI from March 2012 was created through the end of the period, and calculated the differences between the actual and forecasted values.

RESULTS

Data indicate that RSI increased over time, specifically following the release of the movie Concussion. The peak in RSI (100) over this timespan was following the release of Aaron Hernandez's autopsy results in 2017, which was 87.8 (95 % CI: 8.7-15.7) higher than forecasted, showing a 720.3 % increase in RSI. While research was published regarding CTE in 2005, the first major spike in search interest occurred after Junior Seau died in 2012. Increasing public interest in CTE continued when media exposure conveyed autopsies of former NFL players, the movie Concussion, and the release of The Killer Inside: The Mind of Aaron Hernandez. Given this increased interest in CTE, we recommend that media broadcasters become more educated on brain injuries, as well as the movement of Brain Injury Awareness Month and Concussion Awareness Day.

CONCLUSIONS

There has been an increase in public interest in CTE from 2004 through 2022 with surges following media releases of events involving NFL players. Therefore, physicians and media broadcasters must create partnerships to better educate the public about head injuries and the effects of CTE.

Perceived Chronic Traumatic Encephalopathy and Suicidality in Former Professional Football Players

Importance

Participation in American-style football (ASF) has been linked to chronic traumatic encephalopathy neuropathological change (CTE-NC), a specific neuropathologic finding that can only be established at autopsy. Despite being a postmortem diagnosis, living former ASF players may perceive themselves to have CTE-NC. At present, the proportion and clinical correlates of living former professional ASF athletes with perceived CTE who report suicidality are unknown.

Objective

To determine the proportion, clinical correlates, and suicidality of living former professional ASF players with perceived CTE.

Design, Setting, and Participants

A cross-sectional study within the Football Players Health Study at Harvard University was conducted from 2017 to 2020. Using electronic and paper surveys, this population-based study included former ASF players who contracted with a professional league from 1960 to 2020 and volunteered to fill out a baseline survey. Data for this study were analyzed from June 2023 through March 2024.

Exposures

Data included demographics, football-related exposures (eg, position, career duration), and current health problems (anxiety, attention-deficit/hyperactivity disorder, depression, diabetes, emotional and behavioral dyscontrol symptoms, headache, hyperlipidemia, hypertension, low testosterone level, pain, sleep apnea, and subjective cognitive function).

Main Outcomes and Measures

The proportion of participants reporting perceived CTE. Univariable and multivariable models were used to determine clinical and suicidality correlates of perceived CTE.

Results

Among 4180 former professional ASF players who volunteered to fill out a baseline survey, 1980 (47.4%) provided follow-up data (mean [SD] age, 57.7 [13.9] years). A total of 681 participants (34.4%) reported perceived CTE. Subjective cognitive difficulties, low testosterone level, headache, concussion signs and symptoms accrued during playing years, depressive/emotional and behavioral dyscontrol symptoms, pain, and younger age were significantly associated with perceived CTE. Suicidality was reported by 171 of 681 participants with perceived CTE (25.4%) and 64 of 1299 without perceived CTE (5.0%). After adjusting for established suicidality predictors (eg, depression), men with perceived CTE remained twice as likely to report suicidality (odds ratio, 2.06; 95% CI, 1.36-3.12; P < .001).

Conclusions and Relevance

This study found that approximately one-third of living former professional ASF players reported perceived CTE. Men with perceived CTE had an increased prevalence of suicidality and were more likely to have health problems associated with cognitive impairment compared with men without perceived CTE. Perceived CTE represents a novel risk factor for suicidality and, if present, should motivate the diagnostic assessment and treatment of medical and behavioral conditions that may be misattributed to CTE-NC.

Epidemiological Principles in Claims of Causality: An Enquiry into Repetitive Head Impacts (RHI) and Chronic Traumatic Encephalopathy (CTE)

Determining whether repetitive head impacts (RHI) cause the development of chronic traumatic encephalopathy (CTE)-neuropathological change (NC) and whether pathological changes cause clinical syndromes are topics of considerable interest to the global sports medicine community. In 2022, an article was published that used the Bradford Hill criteria to evaluate the claim that RHI cause CTE. The publication garnered international media attention and has since been promoted as definitive proof that causality has been established. Our counterpoint presents an appraisal of the published article in terms of the claims made and the scientific literature used in developing those claims. We conclude that the evidence provided does not justify the causal claims. We discuss how causes are conceptualised in modern epidemiology and highlight shortcomings in the current definitions and measurement of exposures (RHI) and outcomes (CTE). We address the Bradford Hill arguments that are used as evidence in the original review and conclude that assertions of causality having been established are premature. Members of the scientific community must be cautious of making causal claims until the proposed exposures and outcomes are well defined and consistently measured, and findings from appropriately designed studies have been published. Evaluating and reflecting on the quality of research is a crucial step in providing accurate evidence-based information to the public.

Base rates of healthy community-dwelling adults meeting criteria for traumatic encephalopathy syndrome and levels of chronic traumatic encephalopathy certainty

Objective: The National Institute of Neurological Disorders and Stroke (NINDS) recently revised criteria for Traumatic Encephalopathy Syndrome (TES) (Katz et al.), aiming to improve the specificity of former TES criteria (Montenigro et al.) and adding methods to gauge certainty of underlying Chronic Traumatic Encephalopathy (CTE). This study examined base rates of Montenigro et al. and Katz et al. TES criteria in healthy community-dwelling adults. Method: Participants consisted of healthy adults (n = 835; M = 48.1 ± 18.2 years-old, range = 18-85; 37.1% male; 64.1% White) without known history of neurotrauma or psychiatric or neurological conditions. The former and current TES criteria were operationalized using the NIH Toolbox Cognition, Motor, and Emotion batteries and PROMIS-29. Results: Per Katz et al. criteria, 36.9% had symptoms Suggestive of CTE (i.e. either cognitive impairment or neurobehavioral dysregulation), 4.1% had Possible CTE (i.e. requiring cognitive impairment and two additional criteria), and 0.8% had Probable CTE (i.e. requiring cognitive impairment and three additional criteria). The requirement of cognitive impairment for Possible CTE certainty decreased the base rate of Possible CTE tenfold from Montenigro et al. criteria (40.1%). Conclusion: The Katz et al. criteria were met less frequently by healthy adults than the Montenigro et al. criteria. Requiring cognitive impairment and more supportive TES features when gauging CTE certainty may reduce false-positive diagnoses. This finding supports the role of neuropsychologists in the diagnosis and monitoring of patients in TES research studies. To assess specificity, future research should examine base rates of Katz et al. criteria in other psychiatric and neurological conditions.

Substantia Nigra Pathology, Contact Sports Play, and Parkinsonism in Chronic Traumatic Encephalopathy

Importance

Parkinsonism is associated with traumatic brain injury and chronic traumatic encephalopathy (CTE), a neurodegenerative disease associated with repetitive head impact (RHI) exposure, but the neuropathologic substrates that underlie parkinsonism in individuals with CTE are yet to be defined.

Objective

To evaluate the frequency of parkinsonism in individuals with CTE and the association of RHI and neuropathologic substrates with parkinsonism in these individuals.

Design, Setting, and Participants

This cross-sectional study included brain donors with neuropathologically diagnosed CTE without other significant neurodegenerative disease and with information on parkinsonism from the Understanding Neurologic Injury and Traumatic Encephalopathy brain bank between July 2015 and May 2022.

Exposure

Years of contact sports participation as a proxy for RHI.

Main Outcomes and Measures

The main outcomes were frequency of parkinsonism in individuals with CTE and associations between (1) RHI with substantia nigra (SN) Lewy bodies (LBs) and neurofibrillary tangles (NFTs); (2) LBs, NFTs, and arteriolosclerosis with SN neuronal loss; and (3) SN neuronal loss, LBs, NFTs, and arteriolosclerosis with parkinsonism, tested by age-adjusted logistic regressions.

Results

Of 481 male brain donors with neuropathologically diagnosed CTE, parkinsonism occurred frequently in individuals with CTE (119 [24.7%]; 362 [75.3%] did not have parkinsonism). Participants with parkinsonism had a higher mean (SD) age at death (71.5 [13.0] years) than participants without parkinsonism (54.1 [19.3] years) (P < .001) and higher rates of dementia (104 [87.4%] vs 105 [29.0%]), visual hallucinations (45 [37.8%] vs 51 [14.1%]), and probable rapid eye movement sleep behavior disorder (52 [43.7%] vs 58 [16.0%]) (P < .001 for all). Participants with parkinsonism had a more severe CTE stage (eg, stage IV: 35 [29.4%] vs 39 [10.8%]) and nigral pathology than those without parkinsonism (NFTs: 50 of 117 [42.7%] vs 103 of 344 [29.9%]; P = .01; neuronal loss: 61 of 117 [52.1%] vs 59 of 344 [17.1%]; P < .001; and LBs: 28 of 116 [24.1%] vs 20 of 342 [5.8%]; P < .001). Years of contact sports participation were associated with SN NFTs (adjusted odds ratio [AOR], 1.04; 95% CI, 1.00-1.07; P = .03) and neuronal loss (AOR, 1.05; 95% CI, 1.01-1.08; P = .02). Nigral neuronal loss (AOR, 2.61; 95% CI, 1.52-4.47; P < .001) and LBs (AOR, 2.29; 95% CI, 1.15-4.57; P = .02) were associated with parkinsonism. However, SN neuronal loss was associated with SN LBs (AOR, 4.48; 95% CI, 2.25-8.92; P < .001), SN NFTs (AOR, 2.51; 95% CI, 1.52-4.15; P < .001), and arteriolosclerosis (AOR, 2.27; 95% CI, 1.33-3.85; P = .002). In American football players, regression analysis demonstrated that SN NFTs and neuronal loss mediated the association between years of play and parkinsonism in the context of CTE (β, 0.012; 95% CI, 0.001-0.038).

Conclusions and Relevance

In this cross-sectional study of contact sports athletes with CTE, years of contact sports participation were associated with SN tau pathology and neuronal loss, and these pathologies were associated with parkinsonism. Repetitive head impacts may incite neuropathologic processes that lead to symptoms of parkinsonism in individuals with CTE.

The Effects of Repetitive Head Impact Exposure on Mental Health Symptoms Following Traumatic Brain Injury

OBJECTIVE

This study aimed to characterize the types and timing of repetitive head impact (RHI) exposures in individuals with moderate to severe traumatic brain injury (TBI) and to examine the effects of RHI exposures on mental health outcomes.

SETTING

TBI Model Systems National Database.

PARTICIPANTS

447 patients with moderate to severe TBI who reported RHI exposure between 2015 and 2022.

DESIGN

Secondary data analysis.

MAIN MEASURES

RHI exposures reported on the Ohio State University TBI Identification Method (OSU TBI-ID) were characterized by exposure category, duration, and timing relative to the index TBI. Mental health outcomes were evaluated at the 5-year follow-up assessment using the Patient Health Questionnaire-9 (PHQ-9) for depression symptoms and the Generalized Anxiety Disorder-7 (GAD-7) for anxiety symptoms.

RESULTS

The majority of RHI exposures were sports-related (61.1%), followed by other causes (20.8%; including falls), repetitive violence/assault (18.8%), and military exposures (6.7%). Males predominantly reported sports and military exposures, while a larger proportion of females reported violence and falls. Sports exposures were most common before the index TBI, while exposures from falls and violence/abuse were most common after TBI. RHI exposures occurring after the index TBI were associated with higher levels of depression (β = 5.05; 95% CI, 1.59-8.50) and anxiety (β = 4.53; 95% CI, 1.02-8.05) symptoms than exposures before the index TBI.

CONCLUSION

The findings emphasize the need to consider RHI exposures and their interaction with TBI when assessing mental health outcomes. Understanding the prevalence and challenges associated with RHI post-TBI can inform targeted interventions and improve the well-being of individuals with TBI. Preventive measures and ongoing care should be implemented to address the risks posed by RHI, particularly in individuals with prior TBI, especially surrounding fall and violence/abuse prevention.

Symptoms of Traumatic Encephalopathy Syndrome are Common in Community-Dwelling Adults

BACKGROUND AND OBJECTIVES

The consensus criteria for traumatic encephalopathy syndrome (TES), the possible in vivo clinical syndrome associated with significant repetitive head impacts, have only been minimally studied to date. This study examined the prevalence of the proposed core clinical features of TES in a sample of healthy adults.

METHODS

A cross-sectional survey study was conducted through ResearchMatch, a national health volunteer registry. Participants were assessed for symptoms of TES based on the 2021 consensus criteria, including prior repetitive head impacts and core clinical features. Additional health information (e.g., concussion history, psychological health, sleep, chronic pain) was also evaluated. The consensus proposed research criteria for TES (i.e., reporting at least one progressive core clinical feature of TES, as in progressive difficulties with episodic memory, executive functioning, or neurobehavioral dysregulation) were applied to the sample.

RESULTS

Out of 1100 participants (average age = 53.6 ± 17.7 years, 55% women), 34.6% endorsed one or more progressive core clinical features of TES. Participants with a significant history of contact sports (i.e., ≥ 5 years total, with ≥ 2 years in high school or beyond) had similar rates of endorsing a progressive core clinical feature of TES compared to those without significant histories of repetitive head impacts (36.4% vs 32.8%, respectively, χ2 = 0.52, p = 0.47). A significant history of repetitive head impacts in sports was not associated with endorsing a core clinical feature of TES in univariable or multivariable models (p > 0.47), whereas current depression/anxiety (odds ratio [OR] = 6.94), a history of psychiatric disorders (OR = 2.57), current sleep problems (OR = 1.56), and younger age (OR = 0.99) were significant predictors of TES status in a multivariable model. In a subsample of 541 participants who denied a lifetime history of contact sports, other forms of repetitive head impacts, and concussions, approximately 31.0% endorsed one or more progressive core clinical features of TES. Additionally, 73.5% of neurotrauma-naïve participants with current anxiety or depression reported at least one core progressive feature of TES, compared with 20.2% of those without clinically significant depression/anxiety symptoms.

CONCLUSIONS

A considerable proportion of adults without a significant history of repetitive head impacts from sports endorsed core TES features, particularly those experiencing mental health symptoms. Having a significant history of contact sports was not associated with endorsing a core progressive clinical feature of TES, whereas other health factors were. These findings underscore the need for validating and refining TES criteria in samples with and without substantial neurotrauma histories.

Clinical implications of head trauma in frontotemporal dementia and primary progressive aphasia

BACKGROUND

Traumatic brain injury (TBI) and repetitive head impacts (RHI) have been linked to increased risk for multiple types of neurodegenerative disease, higher dementia risk, and earlier age of dementia symptom onset, suggesting transdiagnostic implications for later-life brain health. Frontotemporal dementia (FTD) and primary progressive aphasia (PPA) represent a spectrum of clinical phenotypes that are neuropathologically diverse. FTD/PPA diagnoses bring unique challenges due to complex cognitive and behavioral symptoms that disproportionately present as an early-onset dementia (before age 65). We performed a detailed characterization of lifetime head trauma exposure in individuals with FTD and PPA compared to healthy controls to examine frequency of lifetime TBI and RHI and associated clinical implications.

METHODS

We studied 132 FTD/PPA (age 68.9 ± 8.1, 65% male) and 132 sex-matched healthy controls (HC; age 73.4 ± 7.6). We compared rates of prior TBI and RHI (contact/collision sports) between FTD/PPA and HC (chi-square, logistic regression, analysis of variance). Within FTD/PPA, we evaluated associations with age of symptom onset (analysis of variance). Within behavioral variant FTD, we evaluated associations with cognitive function and neuropsychiatric symptoms (linear regression controlling for age, sex, and years of education).

RESULTS

Years of participation were greater in FTD/PPA than HC for any contact/collision sport (8.5 ± 6.7yrs vs. 5.3 ± 4.5yrs, p = .008) and for American football (6.2yrs ± 4.3yrs vs. 3.1 ± 2.4yrs; p = .003). Within FTD/PPA, there were dose-dependent associations with earlier age of symptom onset for TBI (0 TBI: 62.1 ± 8.1, 1 TBI: 59.9 ± 6.9, 2 + TBI: 57.3 ± 8.4; p = .03) and years of American football (0yrs: 62.2 ± 8.7, 1-4yrs: 59.7 ± 7.0, 5 + yrs: 55.9 ± 6.3; p = .009). Within bvFTD, those who played American football had worse memory (z-score: -2.4 ± 1.2 vs. -1.4 ± 1.6, p = .02, d = 1.1).

CONCLUSIONS

Lifetime head trauma may represent a preventable environmental risk factor for FTD/PPA. Dose-dependent exposure to TBI or RHI influences FTD/PPA symptom onset and memory function in bvFTD. Clinico-pathological studies are needed to better understand the neuropathological correlates linking RHI or TBI to FTD/PPA onset and symptoms.

Levels of biomarkers associated with subconcussive head hits in mixed martial arts fighters

Background

Concussion and the damage resulting from this event related to brain function have been widely studied; however, little is known about subconcussive impacts, especially in Mixed Martial Arts (MMA) fighters, which is a combat and full contact sport in which most blows are aimed at the head.

Objective

This study aims to evaluate the biomarker levels associated with subconcussive hits to the head in MMA fighters.

Methods

This is an exploratory study in which 30 male subjects (10 MMA fighters, 10 healthy individuals who practice muscle training, and 10 healthy sedentary individuals) aged between 18 and 32 years (25.4 ± 3.8) were evaluated. These individuals underwent blood collection to assess their Ubiquitin C-terminal hydrolase (UCH-L1), Glial Fibrillary Acidic Protein (GFAP) and Brain Derived Neurotrophic Factor (BDNF) levels before, immediately after and 72 hours after the sparring session (for the fighters) and were compared between groups.

Results

Significant differences were found at baseline between active and healthy fighters in BDNF levels (p = 0.03). A significant reduction of BDNF levels were also observed between the post-immediate and 72h after the sparring session (p = 0.03). No differences were observed in the number or severity of symptoms reported by the fighters.

Conclusion

Despite the exploratory approach, the findings of this study may help to understand the influence of repeated subconcussive hits to the head in MMA fighters, as well as to propose preventive interventions which can minimize the effects of the impact of hits, preserving fighters' neuronal integrity and function.

Chronic Traumatic Encephalopathy

This article focuses on neuropathologic diagnostic criteria for chronic traumatic encephalopathy (CTE) and consensus research diagnostic criteria for traumatic encephalopathy syndrome (TES). CTE as a tauopathy has a unique pattern for diagnosis and differs from other neurodegenerative diseases. We discuss the history, neuropathology, and mechanism of CTE as well as the preliminary reasearch diagnostic criteria for TES, which is the proposed clinical presentation of suspected CTE.

Sports Related Concussion

Sports-related concussions (SRC) have been a topic of interest for decades and are a prevalent risk of sports participation. The definition of SRC continues to evolve but includes a plausible mechanism and associated symptoms of injury. Rates of concussion vary among sports, and many sports have adopted rule changes to limit this risk for its athletes. There has been a considerable effort to prevent the occurrence of SRC, as well as a focus on safe return to learn and sport alike. There is growing concern about the ramifications of concussions, which will continue to warrant further investigation.

The relationship between multiple concussions and multidimensional sleep quality in collegiate-aged, active athletes

OBJECTIVES

Determine the association of cumulative concussion and repetitive head impacts with self-reported sleep quality in healthy collegiate-aged athletes.

METHODS

Collegiate-aged athletes (N = 212; mean age 21.00, 62.7% male) completed semistructured interviews for sport and concussion history and the Pittsburgh Sleep Quality Index (PSQI). Number of concussions was retrospectively determined based on the 1993 American Congress of Rehabilitation Medicine (ACRM) criteria; repetitive head impact was measured based on the cumulative years of contact sport exposure. Associations of number of concussions and repetitive head impact exposure with global PSQI score, overall poor (PSQI >5) vs. good sleep, and binarized subscale scores were tested. Secondary analyses were conducted using alternative concussion criteria and metrics of repetitive head impact.

RESULTS

The number of prior concussions was associated with higher PSQI global scores (B(SE)= 0.50(0.13), p < .001). Participants with more concussions were more likely to be poor sleepers (OR=1.52, p < .001), report poorer sleep quality (OR=1.29, p = .037), longer sleep latency (OR=1.34, p = .005), more sleep disturbances (OR=1.56, p = .001), increased use of sleep medications or sleep aids (OR=1.35, p = .008), and more sleep-related daily dysfunction (OR=1.38, p = .002). Similar results were observed for alternative definitions of concussion. No metric of repetitive head impact was associated with any sleep quality metric.

CONCLUSIONS

More prior concussions, but not repetitive head impact exposure, are associated with worse self-reported sleep, with subscale analyses showing concussion history associated with multiple aspects of subjective sleep quality rather than sleep quantity. Sleep represents an important factor to consider for future research aimed at characterizing and ultimately preventing adverse long-term health outcomes associated with concussion history.

Characterizing Neurobehavioral Dysregulation Among Former American Football Players: Findings From the DIAGNOSE CTE Research Project

OBJECTIVE

Neurobehavioral dysregulation (NBD), a core clinical feature of traumatic encephalopathy syndrome, encompasses neuropsychiatric symptoms reported among individuals with a history of repetitive head impact exposure, including contact sport athletes. The objective of this study was to examine the construct and subconstructs of NBD through a series of factor and cluster analyses.

METHODS

Six clinician-scientists selected self-report questionnaire items relevant to NBD from seven available neuropsychiatric scales through a blinded voting process. These items were subjected to confirmatory factor analyses in a sample of 178 former college and professional American football players and 60 asymptomatic individuals without a history of repetitive head impact exposure. All participants were enrolled in the Diagnostics, Imaging, and Genetics Network for the Objective Study and Evaluation of Chronic Traumatic Encephalopathy Research Project. Factor scores were generated on the basis of the optimal expert-informed model for NBD. Construct validity was assessed with neuropsychiatric scales not included in generation of the factor scores. Cluster analyses with NBD factor scores were used to examine symptom profiles.

RESULTS

Factor analyses confirmed that NBD was composed of four subconstructs: explosivity, emotional dyscontrol, impulsivity, and affective lability. Cluster analyses indicated four distinct symptom profiles of NBD in this group of former football players: asymptomatic (N=80, 45%), short fuse (N=33, 19%), high affective lability (N=34, 19%), and high NBD (N=31, 17%).

CONCLUSIONS

These findings characterize NBD as a multifaceted clinical construct with a heterogeneous presentation, providing a foundation for empirical work on the diagnostic criteria for traumatic encephalopathy syndrome and research on the neurobiological underpinnings of NBD.

'Comprehensive review of emerging drug targets in traumatic brain injury (TBI): challenges and future scope

Traumatic brain injury (TBI) is a complex brain problem that causes significant morbidity and mortality among people of all age groups. The complex pathophysiology, varied symptoms, and inadequate treatment further precipitate the problem. Further, TBI produces several psychiatric problems and other related complications in post-TBI survival patients, which are often treated symptomatically or inadequately. Several approaches, including neuroprotective agents targeting several pathways of oxidative stress, neuroinflammation, cytokines, immune system GABA, glutamatergic, microglia, and astrocytes, are being tried by researchers to develop effective treatments or magic bullets to manage the condition effectively. The problem of TBI is therefore treated as a challenge among pharmaceutical scientists or researchers to develop drugs for the effective management of this problem. The goal of the present comprehensive review is to provide an overview of the several pharmacological targets, processes, and cellular pathways that researchers are focusing on, along with an update on their current state.

The Evaluation and Management of Concussion to Optimize Safe Recovery

Concussion is a mild traumatic brain injury causing temporary neurologic dysfunction. Symptoms following concussion are variable and generally are expected to resolve within about 1 month, but some patients experience persistent and prolonged symptoms. An early return to safe, symptom-limited activity is now favored, using targeted rehabilitation and treatments. Accommodations may be needed to facilitate return-to-school and work following concussion. Athletes should not be cleared for a full return to sport until they have recovered from a concussion and completed a return-to-play progression, in addition to returning to work/school fully.

The Effect of Intranasal Plus Transcranial Photobiomodulation on Neuromuscular Control in Individuals with Repetitive Head Acceleration Events

Objective: This proof-of-concept study was to investigate the relationship between photobiomodulation (PBM) and neuromuscular control. Background: The effects of concussion and repetitive head acceleration events (RHAEs) are associated with decreased motor control and balance. Simultaneous intranasal and transcranial PBM (itPBM) is emerging as a possible treatment for cognitive and psychological sequelae of brain injury with evidence of remote effects on other body systems. Methods: In total, 43 (39 male) participants, age 18-69 years (mean, 49.5; SD, 14.45), with a self-reported history of concussive and/or RHAE and complaints of their related effects (e.g., mood dysregulation, impaired cognition, and poor sleep quality), completed baseline and posttreatment motor assessments including clinical reaction time, grip strength, grooved pegboard, and the Mini Balance Evaluation Systems Test (MiniBEST). In the 8-week interim, participants self-administered itPBM treatments by wearing a headset comprising four near-infrared light-emitting diodes (LED) and a near-infrared LED nasal clip. Results: Posttreatment group averages in reaction time, MiniBEST reactive control subscores, and bilateral grip strength significantly improved with effect sizes of g = 0.75, g = 0.63, g = 0.22 (dominant hand), and g = 0.34 (nondominant hand), respectively. Conclusion: This study provides a framework for more robust studies and suggests that itPBM may serve as a noninvasive solution for improved neuromuscular health.

Medico-legal implications of dementia following concussion in rugby football

There is litigation in respect of dementia in ex-rugby football players. The allegation is that these ex-players have suffered a traumatic encephalopathy syndrome causing dementia and other neurological problems. The syndrome is alleged to have been caused by repeated concussion during play. It is alleged that governing bodies of rugby should have been aware, and players should have been warned, of this risk. The dilemma, for both claimants and defendants, is that there is no agreed definition of the syndrome nor are there any diagnostic tests that confirm or refute this diagnosis. This paper reviews the literature of traumatic encephalopathy syndrome and when governing bodies were aware of the possibility of rugby concussion causing dementia. The legal principles are discussed and a framework for determining the probability of an ex-rugby player having the syndrome is proposed.

Progress in Pharmacologic Management of Neuropsychiatric Syndromes in Neurodegenerative Disorders: A Review

Importance

Neuropsychiatric syndromes (NPSs) are common in neurodegenerative disorders (NDDs); compromise the quality of life of patients and their care partners; and are associated with faster disease progression, earlier need for nursing home care, and poorer quality of life. Advances in translational pharmacology, clinical trial design and conduct, and understanding of the pathobiology of NDDs are bringing new therapies to clinical care.

Observations

Consensus definitions have evolved for psychosis, agitation, apathy, depression, and disinhibition in NDDs. Psychosocial interventions may reduce mild behavioral symptoms in patients with NDD, and pharmacotherapy is available for NPSs in NDDs. Brexpiprazole is approved for treatment of agitation associated with Alzheimer disease dementia, and pimavanserin is approved for treatment of delusions and hallucinations associated with psychosis of Parkinson disease. Trials are being conducted across several of the NDDs, and a variety of mechanisms of action are being assessed for their effect on NPSs.

Conclusions and Relevance

Detection and characterization of NPSs in patients with NDDs is the foundation for excellent care. New definitions for NPSs in NDDs may inform choices regarding clinical trial populations and translate into clinical practice. Psychosocial and pharmacologic therapies may reduce behavioral symptoms and improve quality of life for patients and caregivers. Approved agents may establish regulatory precedents, demonstrate successful trial strategies, and provide the foundation for further advances in treatment development.

Soccer (football) and brain health

Soccer is one of the most popular sports worldwide, played by over 270 million people and followed by many more. Several brain health benefits are promoted by practising soccer and physical exercise at large, which helps contrast the cognitive decline associated with ageing by enhancing neurogenesis processes. However, sport-related concussions have been increasingly recognised as a pressing public health concern, not only due to their acute impact but also, more importantly, due to mounting evidence indicating an elevated risk for the development of neurological sequelae following recurrent head traumas, especially chronic traumatic encephalopathy (CTE). While soccer players experience less frequent concussions compared with other contact or combat sports, such as American football or boxing, it stands alone in its purposeful use of the head to hit the ball (headings), setting its players apart as the only athletes exposed to intentional, sub-concussive head impacts. Additionally, an association between soccer and amyotrophic lateral sclerosis has been consistently observed, suggesting a potential "soccer-specific" risk factor. In this review, we discuss the neurological sequelae related to soccer playing, the emerging evidence of a detrimental effect related to recurrent headings, and the need for implementation of comprehensive strategies aimed at preventing and managing the burden of head impact in soccer.

Unusual combinations of neurodegenerative pathologies with chronic traumatic encephalopathy (CTE) complicates clinical prediction of CTE

BACKGROUND AND PURPOSE

Chronic traumatic encephalopathy (CTE) has gained widespread attention due to its association with multiple concussions and contact sports. However, CTE remains a postmortem diagnosis, and the link between clinical symptoms and CTE pathology is poorly understood. This study aimed to investigate the presence of copathologies and their impact on symptoms in former contact sports athletes.

METHODS

This was a retrospective case series design of 12 consecutive cases of former contact sports athletes referred for autopsy. Analyses are descriptive and include clinical history as well as the pathological findings of the autopsied brains.

RESULTS

All participants had a history of multiple concussions, and all but one had documented progressive cognitive, psychiatric, and/or motor symptoms. The results showed that 11 of the 12 participants had evidence of CTE in the brain, but also other copathologies, including different combinations of tauopathies, and other rare entities.

CONCLUSIONS

The heterogeneity of symptoms after repetitive head injuries and the diverse pathological combinations accompanying CTE complicate the prediction of CTE in clinical practice. It is prudent to consider the possibility of multiple copathologies when clinically assessing patients with repetitive head injuries, especially as they age, and attributing neurological or cognitive symptoms solely to presumptive CTE in elderly patients should be discouraged.

The effects of person-centred active rehabilitation on symptoms of suspected Chronic Traumatic Encephalopathy: A mixed-methods single case design

OBJECTIVE

The objective was to investigate the effectiveness of a person-centred active rehabilitation programme on symptoms associated with suspected Chronic Traumatic Encephalopathy (CTE). This was accomplished by (1) assessing the effect that a person-centred active rehabilitation programme had on participant symptoms, and (2) exploring how temporal contextual factors affected the participants' experience with, and perceived effectiveness of, the active rehabilitation programme.

METHODS

A twelve-month mixed-methods single case experimental research design was used with six cases (participants). Individual cases were involved in a 51-week study period including an initial interview and three-week baseline phase. Cases were then randomly allocated to one of two n-of-1 study designs (i.e., A-B, B-A, B-A, A-B or B-A, A-B, A-B, B-A) where A and B represent a non-intervention and intervention phase, respectively. Interviews were conducted regularly throughout the study whilst outcome measures were assessed at each follow-up. Analysis of the data included visual, statistical, and qualitative analysis.

RESULTS

Visual and statistical analysis of cognitive and executive function, and mindful attention, demonstrated trivial-to-large effects with the summary reflecting positive or unclear results. A mixed picture was observed for mood and behaviour with effects considered trivial-to-large, and the summary demonstrating positive, unclear and negative effects. Qualitative analysis indicated a perceived improvement in outcome measures such as memory, attention, anxiety, and emotional control despite mixed quantitative findings whilst a clear impact of contextual factors, such as COVID-19, the political atmosphere, exercise tolerance, programme progression, and motivation were evident during the intervention.

CONCLUSIONS

This study has provided primary-level evidence to suggest active rehabilitation as a potential intervention for the management of suspected CTE symptoms. This study has also demonstrated the benefit of a person-centred approach to both clinical research and practice, particularly by considering contextual factors for a better understanding of an intervention effect.

Identification of biological indicators for human exposure toxicology in smart cities based on public health data and deep learning

With the acceleration of urbanization, the risk of urban population exposure to environmental pollutants is increasing. Protecting public health is the top priority in the construction of smart cities. The purpose of this study is to propose a method for identifying toxicological biological indicators of human exposure in smart cities based on public health data and deep learning to achieve accurate assessment and management of exposure risks. Initially, the study used a network of sensors within the smart city infrastructure to collect environmental monitoring data, including indicators such as air quality, water quality, and soil pollution. Using public health data, a database containing information on types and concentrations of environmental pollutants has been established. Convolutional neural network was used to recognize the pattern of environmental monitoring data, identify the relationship between different indicators, and build the correlation model between health indicators and environmental indicators. Identify biological indicators associated with environmental pollution exposure through training optimization. Experimental analysis showed that the prediction accuracy of the model reached 93.45%, which could provide decision support for the government and the health sector. In the recognition of the association pattern between respiratory diseases, cardiovascular diseases and environmental exposure factors such as PM2.5 and SO2, the fitting degree between the model and the simulation value reached more than 0.90. The research design model can play a positive role in public health and provide new decision-making ideas for protecting public health.

Pathology of neurodegenerative disease for the general neurologist

Neurodegeneration refers to progressive dysfunction or loss of selectively vulnerable neurones from brain and spinal cord regions. Despite important advances in fluid and imaging biomarkers, the definitive diagnosis of most neurodegenerative diseases still relies on neuropathological examination. Not only has careful clinicopathological correlation shaped current clinical diagnostic criteria and informed our understanding of the natural history of neurodegenerative diseases, but it has also identified conditions with important public health implications, including variant Creutzfeldt-Jakob disease, iatrogenic amyloid-β and chronic traumatic encephalopathy. Neuropathological examination may also point to previously unsuspected genetic diagnoses with potential implications for living relatives. Moreover, detailed neuropathological assessment is crucial for research studies that rely on curated postmortem tissue to investigate the molecular mechanisms responsible for neurodegeneration and for biomarker discovery and validation. This review aims to elucidate the hallmark pathological features of neurodegenerative diseases commonly seen in general neurology clinics, such as Alzheimer's disease and Parkinson's disease; rare but well-known diseases, including progressive supranuclear palsy, corticobasal degeneration and multiple system atrophy and more recently described entities such as chronic traumatic encephalopathy and age-related tau astrogliopathy.

Prospective cohort study of long-term neurological outcomes in retired elite athletes: the Advanced BiomaRker, Advanced Imaging and Neurocognitive (BRAIN) Health Study protocol

INTRODUCTION

Although limited, recent research suggests that contact sport participation might have an adverse long-term effect on brain health. Further work is required to determine whether this includes an increased risk of neurodegenerative disease and/or subsequent changes in cognition and behaviour. The Advanced BiomaRker, Advanced Imaging and Neurocognitive Health Study will prospectively examine the neurological, psychiatric, psychological and general health of retired elite-level rugby union and association football/soccer players.

METHODS AND ANALYSIS

400 retired athletes will be recruited (200 rugby union and 200 association football players, male and female). Athletes will undergo a detailed clinical assessment, advanced neuroimaging, blood testing for a range of brain health outcomes and neuropsychological assessment longitudinally. Follow-up assessments will be completed at 2 and 4 years after baseline visit. 60 healthy volunteers will be recruited and undergo an aligned assessment protocol including advanced neuroimaging, blood testing and neuropsychological assessment. We will describe the previous exposure to head injuries across the cohort and investigate relationships between biomarkers of brain injury and clinical outcomes including cognitive performance, clinical diagnoses and psychiatric symptom burden.

ETHICS AND DISSEMINATION

Relevant ethical approvals have been granted by the Camberwell St Giles Research Ethics Committee (Ref: 17/LO/2066). The study findings will be disseminated through manuscripts in clinical/academic journals, presentations at professional conferences and through participant and stakeholder communications.