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

Catecholamine Dysregulation in Former American Football Players: Findings From the DIAGNOSE CTE Research Project

BACKGROUND AND OBJECTIVES

Disturbances in brain catecholamine activity may be associated with symptoms after exposure to repetitive head impacts (RHIs) or related chronic traumatic encephalopathy (CTE). In this article, we studied CSF catecholamines in former professional and college American football players and examined the relationship with football proxies of RHI exposure, CTE probability, cognitive performance, neuropsychiatric symptoms, and parkinsonism.

METHODS

In this observational cross-sectional study, we examined male former American football players, professional ("PRO") or college ("COL") level, and asymptomatic unexposed male ("UE") individuals from the DIAGNOSE CTE Research Project. Catecholamines-norepinephrine (NE) and its metabolite, 3,4-dihydroxyphenylglycol (DHPG), and dopamine (DA) and its precursor, 3,4-dihydroxyphenylalanine (l-DOPA), and metabolite, 3,4-dihydroxyphenylacetic acid (DOPAC)-were measured in CSF with high-performance liquid chromatography and compared across groups with analysis of covariance. Multivariable linear regression models tested the relationship between CSF catecholamines and proxies of RHI exposure (e.g., total years of playing American football), factor scores for cognition, and neurobehavioral dysregulation (explosivity, emotional dyscontrol, impulsivity, affective lability), as well as depressive/anxiety symptoms, measured with the Beck Depression/Anxiety Inventories. CTE probability and parkinsonism were assessed using the National Institute of Neurological Disorders and Stroke consensus diagnostic criteria for traumatic encephalopathy syndrome (TES), and biomarkers were compared among different diagnostic groups.

RESULTS

The cohort consisted of 120 former American football players (85 PRO players, 35 COL players) and 35 UE participants (age 45-75). Former players had significantly lower levels of NE (mean difference = -0.114, 95% CI -0.190 to -0.038), l-DOPA (-0.121, 95% CI -0.109 to -0.027), and DOPAC (-0.116, 95% CI -0.177 to -0.054) than UE participants. For NE and DOPAC, these overall group differences were primarily due to differences between the PRO and UE cohorts. No significant differences were found across TES-CTE probability subgroups or TES-parkinsonism diagnostic groups. Within the COL cohort, tested as post hoc analyses, higher CSF NE and l-DOPA were associated with higher neurobehavioral dysregulation factor scores, BAI total score, and worse executive functioning and processing speed. CSF DHPG and DOPAC were associated with impulsivity only in this subgroup.

DISCUSSION

We observed reduced CSF catecholamine concentrations in former elite American football players, although the relationship with degree of RHI exposure and the clinical impact needs further study.

The Correlation Between Medication Self-Management with Rational Medication Use Self-Efficacy and Medication Literacy in Patients with Stroke

Objective

To investigate medication self-management in patients with stroke and its relationship with general demographics, self-efficacy and medication literacy.

Methods

This was a cross-sectional study. Patients with stroke who received treatment in Jiangnan University Affiliated Hospital between July 2023 and January 2024 were selected as the study participants. The General Characteristics Questionnaire, the Self-Efficacy for Appropriate Medication Use Scale (SEAMS), the Chinese version of the Drug Literacy Scale and the Self-Administration of Medication tool were used to investigate patients with stroke and to analyse the factors influencing the self-management of their medication.

Results

A total of 210 patients were included in this study. The average score of medication self-management was 66.71 (standard deviation = 9.55), and SEAMS and medication literacy scores were positively correlated with the total score of medication self-management behaviour. Furthermore, we found that the Barthel index (BI), SEAMS and medication literacy scores were the main predictors of medication self-management behaviour (R 2 = 0.790, p < 0.001).

Conclusion

This study found that patients with stroke with a lower BI and higher SEAMS or medication literacy scores also had higher levels of medication self-management. The factors discussed in this study may help develop individualised interventions in medication self-management for patients with stroke.

Schisandrin B Improves Mitochondrial Function and Inhibits HT22 Cell Apoptosis by Regulating Sirt3 Protein

Neurological diseases refer to pathological changes that occur in the brain, spinal cord, and peripheral nerves. Their etiologies are complex, treatment outcomes are poor, and prognoses are unfavorable. Therefore, how to improve the treatment efficacy of neurological diseases is an urgent problem to be addressed in current clinical practice. Schisandrin B, a commonly used traditional Chinese medicine in clinical settings, has anti-tumor, anti-inflammatory, and wound-healing promoting effects. However, there are relatively few studies on its application in the treatment of neurological diseases. In this study, HT22 nerve cells were cultured, and an injury model was constructed by applying H2O2 stimulation to explore the protective effect of Schisandrin B on these cells. The research results showed that compared with the H2O2 group, Schisandrin B could significantly increase the viability (30.872%) and migration ability (42.756%) of HT22 cells, and inhibit the apoptosis of HT22 cells (22.817%). Further exploration of the mechanism revealed that Schisandrin B regulated the mitochondrial dynamic balance and membrane potential level of HT22 cells by upregulating the expression of Sirt3 protein, enhanced the mitochondrial energy metabolism (with an increase of 53.411% in ATP production), and maintained the integrity of the quantity and structure of mitochondria, ultimately exerting a protective effect on HT22 cells.

Collegiate Participation in Repetitive Head Impact Sports Does Not Adversely Affect Gait Dual Task Cost

OBJECTIVES

The purpose of this study was to assess gait related dual task cost (DTC) changes over the course of a collegiate athletic career in both repetitive head impact (RHI) exposed and non-RHI exposed athletes.

SETTING

University Research Laboratory.

PARTICIPANTS

We recruited 47 NCAA intercollegiate athletes and grouped by RHI exposed (N = 27) and non-RHI (N = 20) sports.

DESIGN

Participants completed 5 trials of single task (ST) and 5 trials of dual task (DT) gait with a working memory cognitive challenge both prior to their collegiate athletic careers (pre) and then again after they completed their collegiate athletic careers (post) (mean 1173 ± 341 days between tests) in this prospective longitudinal design. To assess for changes over the course of a career, separate 2 (group: RHI, non-RHI) × 2 (time: pre, post) mixed design ANOVA were performed for each dependent variable of interest (DTC gait velocity and DTC step length) and the model was adjusted for concussion history at the time of test and sex.

MAIN MEASURES

Gait velocity and step length DTC.

RESULTS

There were no significant group by time interactions for DTC gait velocity (F = 0.517, P = .476, η2 = 0.012) or DTC step length ((F = 0.206, P = .652, η2 = 0.005).

CONCLUSIONS

The primary finding of this study indicated no difference between RHI exposed and non-RHI exposed athletes gait DTC performance between the beginning and conclusion of their collegiate athletic careers. While the long-term effects of RHI remain to be fully determined, these results suggest that RHI may not adversely affect ST or DT gait performance when the individual is young.

Concussions in Baseball Players

Sports-related concussion represents a unique type of brain injury because the goal of medical care is to return the athlete safely and expeditiously to the same activity that led to the concussion. The Sport Concussion Assessment Tool has standardized assessment of concussed athletes and their return to play. Advances in brain imaging, assessment of molecular biomarkers in blood and other body fluids, and accurate wearable sensors of force and acceleration are being applied to the study of concussion in athletes. In conjunction with long-term outcome data, such technologies will continue to make athletic competition as safe as possible.

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.

Characterizing white matter and vascular pathologies in brain donors exposed to repetitive head impacts

Chronic traumatic encephalopathy (CTE) is a progressive brain disease linked to repetitive head impacts (RHI), often incurred from contact sports, and can lead to dementia. Here, we investigated the association between RHI and white matter/vascular neuropathologies and their relative contribution to dementia status in deceased men 50 + years old with and without exposure to RHI from various types of contact and collision sports. Our sample included two RHI groups from the UNITE brain bank: (1) American Football players (RHI-AF, n = 79), and (2) non-AF contact and collision sport athletes (e.g., boxing, rugby; RHI-CCS, n = 49). Controls included similarly aged (± 5 years) male brain donors without RHI. A modified ischemic injury scale (mIIS) served as a global measure of white matter and vascular neuropathologies, encompassing nine subcomponents. Dementia was determined through diagnostic consensus conference based on interviews with families. Using linear regression models controlling for age at death, mIIS was different in RHI-AF versus non-RHI only (p = 0.036). Subsequent logistic regression of each mIIS subcomponent, controlling for age at death, demonstrated that worse white matter rarefaction (RHI-AF; Beta = 1.42, [95% CI 2.03-8.43]; RHI-CCS; Beta = 1.93, [95% CI 2.35-20.17]) and hippocampal sclerosis (RHI-AF; Beta = 2.01, [95% CI 2.69-20.81]; RHI-CCS; Beta = 2.19, [95% CI 2.49-32.10]) was more common in RHI groups from their controls. Further, logistic regressions found that higher global mIIS correlated with increased odds of dementia in only the RHI-AF group (p = 0.02), driven by white matter rarefaction (β = 0.94, [95% CI 1.66-4.00]) and hippocampal sclerosis (β = 1.08, [95% CI 1.35-6.42]). There were similar findings in RHI-CCS group for odds of dementia (p = 0.048), including white matter rarefaction (β = 0.68, [95% CI 1.22-3.21], p = 0.05). Overall, these results demonstrate that white matter  rarefaction and hippocampal sclerosis are linked to RHI exposure across all types of contact sports. Further, these pathologies contribute to dementia independent of p-tau pathology in American football players.

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.

Does white matter and vascular injury from repetitive head impacts lead to a novel pattern on T2 FLAIR MRI? A hypothesis proposal and call for research

The goal of this paper is to introduce the hypothesis that white matter (WM) and vascular injury are long-term consequences of repetitive head impacts (RHI) that result in a novel T2 fluid attenuated inversion recovery (FLAIR) magnetic resonance imaging pattern. A non-systematic literature review of autopsy and FLAIR studies of RHI-exposed adults was first conducted as a foundation for our hypothesis. A case series of RHI-exposed participants is presented to illustrate the unique FLAIR WM hyperintensities (WMH) pattern. Current literature shows a direct link between RHI and later-life WM/vascular neuropathologies, and that FLAIR WMH are associated with RHI, independent of modifiable vascular risk factors. Initial observations suggest a distinctive pattern of WMH in RHI-exposed participants, termed RHI-associated WMH (RHI-WMH). RHI-WMH defining features are as follows: (1) small, punctate, non-confluent, (2) spherical, and (3) proximal to the gray matter. Our hypothesis serves as a call for research to empirically validate RHI-WMH and clarify their biological and clinical correlates. HIGHLIGHTS: Repetitive head impacts (RHI) have been associated with later-life white matter (WM) and vascular neuropathologies. T2 FLAIR MRI of RHI-exposed participants reveals a potentially unique WM hyperintensity (WMH) pattern that is termed RHI-associated WMH (RHI-WMH). RHI-WMH are characterized as (1) small, punctate, and non-confluent, (2) spherical, and (3) proximal to the gray matter at an area anatomically susceptible to impact injury, such as the depths of the cortical sulci.

Traumatic Encephalopathy Syndrome: Head Impact Exposure and Blood Biomarkers in Professional Combat Athletes

OBJECTIVE

This study aimed to (1) determine whether there was an association between a diagnosis of traumatic encephalopathy syndrome (TES) and changes in three specific serum biomarkers, and (2) determine head impact exposure thresholds among both TES+ and TES- groups.

SETTING

Data were collected from Cleveland Clinic's Professional Athletes Brain Health Study (PABHS).

PARTICIPANTS

This study included 192 professional combat athletes, 35 years of age and older. Athletes must be actively fighting or retired with a minimum of 10 professional fights over their careers.

DESIGN/INTERVENTION

This was a retrospective observational study of the PABHS longitudinal cohort.

MAIN MEASURES

The generalized linear model with the generalized estimating equation for repeated measurements was used to compare various biomarkers between both active and retired TES- and TES+ groups.

RESULTS

The odds ratio for TES diagnosis was 5.44 (95% CI = 2.48, 11.94; P < .0001) among active fighters and 10.75 (95% CI = 3.52, 32.85; P < .0001) among retired fighters, indicating the odds for a TES diagnosis were over 5 times greater for active fighters with every fight completed at or beyond 30 professional fights. Retired fighters had 10 times greater odds of TES diagnosis with every fight completed at or beyond 15 professional fights. Likewise, the odds of a TES diagnosis were 2.0% (95% CI = 0.3, 3.1; P = 0.0039) greater with each pg/mL increase of glial fibrillary acidic protein (GFAP). No relationship was observed between a TES diagnosis and neurofilament light chain or P-tau231.

CONCLUSION

This study provides preliminary evidence that progressively elevated levels of the GFAP blood biomarker increase the odds of a TES diagnosis among retired professional fighters. Further evaluation is required to improve clarity and understanding of the relationship between progressive changes in the GFAP blood biomarker and a TES diagnosis, specifically evaluating the duration of chronicity and exposure thresholds.

18F-MK-6240 tau PET in patients at-risk for chronic traumatic encephalopathy

BACKGROUND

Molecular biomarkers of chronic traumatic encephalopathy (CTE) are lacking. We evaluated 18F-MK-6240 tau PET as a biomarker for CTE. Two studies were done: (1) 3H-MK-6240 autoradiography and an in-vitro brain homogenate binding studies on postmortem CTE tissue, (2) an in-vivo 18F-MK-6240 tau PET study in former American football players.

METHODS

Autoradiography and in-vitro binding studies were done using 3H-MK-6240 on frozen temporal and frontal cortex tissue from six autopsy cases with stage III CTE compared to Alzheimer's disease. Thirty male former National Football League (NFL) players with cognitive concerns (mean age = 58.9, SD = 7.8) completed tau (18F-MK-6240) and Aβ (18F-Florbetapir) PET. Controls included 39 Aβ-PET negative, cognitively normal males (mean age = 65.7, SD = 6.3). 18F-MK-6240 SUVr images were created using 70-90 min post-injection data with inferior cerebellar gray matter as the reference. We compared SUVr between players and controls using voxelwise and region-of-interest approaches. Correlations between 18F-MK-6240 SUVr and cognitive scores were tested.

RESULTS

All six CTE stage III cases had Braak NFT stage III but no neuritic plaques. Two had Thal Phase 1 for Aβ; one showed a laminar pattern of 3H-MK-6240 autoradiography binding in the superior temporal cortex and less so in the dorsolateral frontal cortex, corresponding to tau-immunoreactive lesions detected using the AT8 antibody (pSer202/pThr205 tau) in adjacent tissue sections. The other CTE cases had low frequencies of cortical tau-immunoreactive deposits and no well-defined autoradiography binding. In-vitro 3H-MK-6240 binding studies to CTE brain homogenates in the case with autoradiography signal indicated high binding affinity (KD = 2.0 ± 0.9 nM, Bmax = 97 ± 24 nM, n = 3). All NFL players had negative Aβ-PET. There was variable, low-to-intermediate intensity 18F-MK-6240 uptake across participants: 16 had no cortical signal, 7 had medial temporal lobe (MTL) uptake, 2 had frontal uptake, and 4 had MTL and frontal uptake. NFL players had higher SUVr in the entorhinal cortex (d = 0.86, p = 0.001), and the parahippocampal gyrus (d = 0.39, p = 0.08). Voxelwise regressions showed increased uptake in NFL players in two bilateral anterior MTL clusters (p < 0.05 FWE). Higher parahippocampal and frontal-temporal SUVrs correlated with worse memory (r = -0.38, r = -0.40) and semantic fluency (r = -0.38, r = -0.48), respectively.

CONCLUSION

We present evidence of 3H-MK-6240 in-vitro binding to post-mortem CTE tissue homogenates and in vivo 18F-MK-6240 PET binding in the MTL among a subset of participants. Additional studies in larger samples and PET-to-autopsy correlations are required to further elucidate the potential of 18F-MK-6240 to detect tau pathology in CTE.

Enlarged cavum septum pellucidum as a neuroimaging signature of head impact exposure

Cavum septum pellucidum (CSP) is commonly observed upon neuroimaging examination in individuals exposed to repetitive head impacts (RHI) and post-mortem in cases with chronic traumatic encephalopathy. Consequently, CSP has been proposed as a potential biomarker for RHI-related neurodegeneration, yet prevalence estimates of CSP across other neurodegenerative diseases and its clinical implications are largely unknown. We assessed CSP prevalence and clinical correlates in individuals with RHI exposure, a history of traumatic brain injury (TBI), a neurodegenerative disease (i.e. Alzheimer's disease or frontotemporal dementia) and normal cognition. The primary group of interest, i.e. individuals exposed to RHI in contact sports or military service (n = 65; mean exposure 21.58 years), was compared against age- and sex-matched participants with TBI (n = 57; number of TBI range: 1-5) and non-exposed participants of the Amsterdam Dementia Cohort (Alzheimer's disease, n = 30; frontotemporal dementia, n = 24; normal cognition, n = 27). Structural 3D brain MRI scans were visually rated for CSP grade (ranging 0-4) by two raters blinded to the clinical information. A CSP of at least Grade 2 was considered enlarged/abnormal. Inter-rater reliability was assessed with Cohens' weighted Kappa (κ). We investigated whether prevalence of enlarged CSP differed between groups and assessed associations with neuropsychological outcomes (verbal memory, processing speed, mental flexibility and semantic fluency), neuropsychiatric symptoms (neuropsychiatric inventory), ventricular enlargement as measured with Evan's index and MRI volumes of composite regions (limbic, temporal-meta regions and the whole brain). Inter-rater reliability was substantial [κ = 0.734 (95% confidence interval 0.67-0.80)]. An enlarged CSP was more often observed in the RHI group (44.6%) compared with individuals with Alzheimer's disease [13.3%, odds ratio (OR) = 5.24 (1.79-19.26)], frontotemporal dementia [16.7%, OR = 4.03 (1.35-15.02)] and normal cognition [18.5%, OR = 3.54 (1.27-11.62)], all P FDR < 0.05, but not compared with the TBI group [29.8%, OR = 1.90 (0.90-4.06), P FDR  = 0.094]. In those with RHI, enlarged CSP was associated with lower outcomes on verbal memory learning (η² = 0.09, P FDR = 0.023) and recall (η² = 0.08, P FDR = 0.030). For TBI, enlarged CSP was associated with lower performance on verbal memory learning; however, this lost significance after multiple comparison correction (η² = 0.014, P FDR = 0.09). Enlarged CSP was not associated with the composite MRI volumes, ventricular enlargement or neuropsychiatric symptoms. In summary, enlarged CSP was more prevalent in RHI-exposed individuals compared with individuals with a neurodegenerative disease or normal cognition, but not compared with TBI, and was associated with lower verbal memory performance in the RHI group. Our study highlights enlarged CSP as a potential consequence of long-term head impact exposure and, to a lesser extent, TBI, rather than a general consequence of neurodegeneration.

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.

Repetitive head impacts induce neuronal loss and neuroinflammation in young athletes

Repetitive head impacts (RHI) sustained from contact sports are the largest risk factor for chronic traumatic encephalopathy (CTE). Currently, CTE can only be diagnosed after death and the multicellular cascade of events that trigger initial hyperphosphorylated tau (p-tau) deposition remain unclear. Further, the symptoms endorsed by young individuals with early disease are not fully explained by the extent of p-tau deposition, severely hampering development of therapeutic interventions. Here, we show that RHI exposure associates with a multicellular response in young individuals (<51 years old) prior to the onset of CTE p-tau pathology that correlates with number of years of RHI exposure. Leveraging single nucleus RNA sequencing of tissue from 8 control, 9 RHI-exposed, and 11 low stage CTE individuals, we identify SPP1+ inflammatory microglia, angiogenic and inflamed endothelial cell profiles, reactive astrocytes, and altered synaptic gene expression in excitatory and inhibitory neurons in all individuals with exposure to RHI. Surprisingly, we also observe a significant loss of cortical sulcus layer 2/3 neurons in contact sport athletes compared to controls independent of p-tau pathology. Finally, we identify TGFB1 as a potential signal mediating microglia-endothelial cell cross talk through ligand-receptor analysis. These results provide robust evidence that multiple years of RHI exposure is sufficient to induce lasting cellular alterations that may underlie p-tau deposition and help explain the early pathogenesis in young former contact sport athletes. Furthermore, these data identify specific cellular responses to repetitive head impacts that may direct future identification of diagnostic and therapeutic strategies for CTE.

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.

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.

Information seeking behaviors and attitudes of wives of former football players regarding chronic traumatic encephalopathy

This study examines CTE-related knowledge and information-seeking behaviors of caregivers of persons who are at high risk of CTE. Online survey responses were collected from 64 females, ages 18-74, who were married to former college, semiprofessional, or professional football players and were fluent in English. Ranging from 0 to 18, a score was calculated to represent level of CTE knowledge. Participants were classified into groups based on their spouse's reported symptoms and diagnosis. Approximately 87% of participants reported that their spouses have been diagnosed with a football-related concussion and were significantly more likely to seek out information from a healthcare provider, a scientific journal or article, and post/comment on social media compared to spouses of symptomatic/undiagnosed and non-symptomatic groups. Participants reported 77% of available information as probably true, with social media thought to be highly credible. Highest levels of dissatisfaction were reported for league-sponsored websites and physicians/healthcare providers. Although the majority of participants sought CTE related information on regular or social media, and the internet, information sources differed amongst the groups. These findings may help healthcare providers and organizations develop more effective health-related educational programs that will help the wives make informed decisions regarding care for their spouses with respect to CTE.

Investigating the Impact of Turmeric on Neuroinflammation and Degenerative Changes in Repetitive Traumatic Brain Injuries: Insights from Murine Model

Objective

Traumatic brain injury (TBI) is a leading cause of death and disability worldwide. Preclinical and clinical studies investigating the effects of curcumin on TBI indicate that curcumin can modulate essential signaling pathways and molecules that mediate neuroinflammation in TBI. This study aimed to explore the effects of turmeric on neuroinflammation and neurodegenerative disorder following repetitive traumatic brain injuries (rTBIs) in a rat model.

Methods

Sixty male Rattus norvegicus were housed in a controlled environment. A modified Marmarou weight drop model was used. Turmeric extract was administered once daily in the morning. The avidin-biotin-peroxidase complex technique was used to evaluate the expression of all markers. Following incubation with normal rabbit serum, the slides were subsequently incubated with monoclonal antibodies targeting tau protein (AT-8), TAR DNA-binding protein 43 (TDP-43), glial fibrillary acidic protein (GFAP), and tumor necrosis factor (TNF)-α.

Results

rTBI significantly increased the levels of inflammatory markers, such as TNF-α and GFAP. A substantial decrease of TNF-α expression was observed in the treatment group. A distinct trend was observed for GFAP expression, which was markedly decreased after the rest period compared to that in the trauma group. Phosphorylated tau expression decreased in both the treatment and pretreatment groups relative to that in the trauma and rest groups. TDP-43 expression was also significantly decreased in the treatment and pretreatment groups.

Conclusion

In conclusion, Turmeric demonstrates significant potential as a neuroprotective and anti-inflammatory agent in rTBI, especially when used as a preventive measure. Our findings challenge the significance of rest in concussion management.

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.

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.

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.

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.