Neuropathologic and Clinical Findings in Young Contact Sport Athletes Exposed to Repetitive Head Impacts

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.

Shared Decision-Making About Returning to Sport After Recovery From Pediatric Concussion: Clinician Perspectives

OBJECTIVE

Describe how sports medicine clinicians support decision making about sport participation after concussion recovery with adolescent patients and their parents. Specific areas of inquiry related to how clinicians framed the decision, what factors they considered in how they approached the decision process, and how they navigated discordance within families.

DESIGN

Qualitative study.

SETTING

Tertiary care sports medicine clinics at 4 children's hospitals in the United States.

PARTICIPANTS

Individual interviews were conducted with 17 clinicians practicing in sports medicine settings.

INTERVENTIONS

N/A.

MAIN OUTCOME MEASURES

Semi-structured interviews explored clinician approaches to supporting decision making, with the question guide informed by components of the Ottawa Decision Support Framework.

RESULTS

Clinicians routinely incorporated aspects of shared decision making (SDM) into their conversations with families. This included ensuring all parties were informed about risk and aligned behind a shared value of adolescent well-being. Mediation strategies were used to manage discordance between adolescents and their parents, and between parents. These strategies aimed to facilitate a decision that was adolescent centered. When clinicians believed that there was a medical benefit to modifying the adolescent's sport participation practices, or when they did not believe the athlete was psychologically ready to return to the sport in which they were injured, they initiated conversations about alternative activities. In such situations, they used persuasive communication practices to encourage families to strongly consider this option.

CONCLUSION

The strengths and strategies used by sports medicine clinicians in this study provide a foundation for guidance or intervention development aimed at supporting SDM after concussion with adolescents and their families.

Multiparameter cortical surface morphology in former amateur contact sport athletes

The lifetime effects of repetitive head impacts have captured considerable public and scientific interest over the past decade, yet a knowledge gap persists in our understanding of midlife neurological well-being, particularly in amateur level athletes. This study aimed to identify the effects of lifetime exposure to sports-related head impacts on brain morphology in retired, amateur athletes. This cross-sectional study comprised of 37 former amateur contact sports athletes and 21 age- and sex-matched noncontact athletes. High-resolution anatomical, T1 scans were analyzed for the cortical morphology, including cortical thickness, sulcal depth, and sulcal curvature, and cognitive function was assessed using the Dementia Rating Scale-2. Despite no group differences in cognitive functions, the contact group exhibited significant cortical thinning particularly in the bilateral frontotemporal regions and medial brain regions, such as the cingulate cortex and precuneus, compared to the noncontact group. Deepened sulcal depth and increased sulcal curvature across all four lobes of the brain were also notable in the contact group. These data suggest that brain morphology of middle-aged former amateur contact athletes differs from that of noncontact athletes and that lifetime exposure to repetitive head impacts may be associated with neuroanatomical changes.

Functional connectivity changes in neurodegenerative biomarker-positive athletes with repeated concussions

Multimodal biomarkers may identify former contact sports athletes with repeated concussions and at risk for dementia. Our study aims to investigate whether biomarker evidence of neurodegeneration in former professional athletes with repetitive concussions (ExPro) is associated with worse cognition and mood/behavior, brain atrophy, and altered functional connectivity. Forty-one contact sports athletes with repeated concussions were divided into neurodegenerative biomarker-positive (n = 16) and biomarker-negative (n = 25) groups based on positivity of serum neurofilament light-chain. Six healthy controls (negative for biomarkers) with no history of concussions were also analyzed. We calculated cognitive and mood/behavior composite scores from neuropsychological assessments. Gray matter volume maps and functional connectivity of the default mode, salience, and frontoparietal networks were compared between groups using ANCOVAs, controlling for age, and total intracranial volume. The association between the connectivity networks and sports characteristics was analyzed by multiple regression analysis in all ExPro. Participants presented normal-range mean performance in executive function, memory, and mood/behavior tests. The ExPro groups did not differ in professional years played, age at first participation in contact sports, and number of concussions. There were no differences in gray matter volume between groups. The neurodegenerative biomarker-positive group had lower connectivity in the default mode network (DMN) compared to the healthy controls and the neurodegenerative biomarker-negative group. DMN disconnection was associated with increased number of concussions in all ExPro. Biomarkers of neurodegeneration may be useful to detect athletes that are still cognitively normal, but with functional connectivity alterations after concussions and at risk of dementia.

An Assessment of Existing Sport-Related Concussion Guidelines in Ireland: The Need for a United Approach

In 2014, an Irish parliament white paper called for greater addressing of sport-related concussions (SRCs) in Ireland, requesting the adoption of the Concussion in Sport Group's (CISGs) guidelines and greater consistency in SRC return to play (RTP) management. Ten years later, it is unclear how these requests have been addressed. Recently, the United Kingdom's government centralised guidelines to one SRC document for all grassroots sports. This study aimed to investigate all publicly available SRC guidance in Irish sports and national governing bodies (NGBs) to determine if centralised guidelines are warranted. Sport Ireland and the Irish Federation of Sports were searched for all recognised NGBs and sports in Ireland. Websites were searched for any information pertaining to SRCs and data were extracted and collated in Microsoft Excel. In total, 15 of 83 sports and/or NGBs included SRC guidance, nine of which provided RTP protocols. Various iterations of the CISGs guidance and tools were implemented. Several sports with a documented SRC risk had no guidelines present. The findings indicate disjointed and outdated guidance across Irish sport. Additionally, there are sports with a documented concussion risk that have no SRC guidance available. This study provides support for centralised guidelines to be adopted in Irish grassroots sports.

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

BACKGROUND AND PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Associations between repetitive head impact exposure and midlife mental health wellbeing in former amateur athletes

Introduction

Repetitive head impacts (RHI) have been suggested to increase the risk of developing a neurodegenerative disease, and many of these individuals develop a preceding mental health diagnosis. Given the lack of studies among amateur athletes, this study aimed to examine mental health outcomes in middle-aged amateur athletes who have been exposed to RHI through contact sport participation.

Methods

This is a single site, cohort study involving former amateur athletes aged between 30 and 60 with at least 10 years of organized contact or non-contact sport participation. All participants completed demographic and mental health questionnaires. Mental health outcomes included symptoms related to depression, anxiety, post-traumatic stress disorder (PTSD), attention deficit hyperactive disorder (ADHD), and aggression. Self-reported data on mental health diagnoses and associated prescription were elicited and used to estimate odds ratios (OR).

Results

Data from 41 contact athletes and 22 age/sex-matched non-contact athletes were available for analysis. The contact group exhibited a 2.25-fold higher likelihood of being diagnosed with mental health disorders and 1.29-fold higher likelihood of using associated medications compared to the non-contact group. The contact group reported significantly higher PTSD-related symptoms [4.61 (0.03,9.2), p=0.05] compared to the non-contact control group. While not statistically significant, the contact group showed increased depressive [2.37 (0.05, 4.79), p=0.07] and ADHD symptoms [4.53 (0.51, 9.57), p=0.08] compared to controls. In a secondary analysis, a distinct trend emerged within the contact group, revealing pronounced elevations in mental health symptoms among individuals with lower socioeconomic status (<$50,000/year) compared to higher income subgroups, and these symptoms decreased as income levels rose [depression: -3.08 (-4.47, -1.7), p<0.001; anxiety: -1.95 (-3.15, -0.76), p=0.002; ADHD: -4.99 (-8.28, -1.69), p=0.004; PTSD: -4.42 (-7.28, -1.57), p=0.003; aggression: -6.19 (-11.02, -1.36), p=0.01]. This trend was absent in the non-contact control group.

Discussion

Our data suggest that even individuals at the amateur level of contact sports have an increased likelihood of being diagnosed with mental health disorders or experiencing mental health symptoms compared to non-contact athletes. Our findings indicate that socioeconomic status may have an interactive effect on individuals' mental health, particularly among those with a long history of RHI exposure.

Cortical circuit principles predict patterns of trauma induced tauopathy in humans

Connections in the cortex of diverse mammalian species are predicted reliably by the Structural Model for direction of pathways and signal processing (reviewed in 1,2). The model is rooted in the universal principle of cortical systematic variation in laminar structure and has been supported widely for connection patterns in animals but has not yet been tested for humans. Here, in postmortem brains of individuals neuropathologically diagnosed with chronic traumatic encephalopathy (CTE) we studied whether the hyperphosphorylated tau (p-tau) pathology parallels connection sequence in time by circuit mechanisms. CTE is a progressive p-tau pathology that begins focally in perivascular sites in sulcal depths of the neocortex (stages I-II) and later involves the medial temporal lobe (MTL) in stages III-IV. We provide novel quantitative evidence that the p-tau pathology in MTL A28 and nearby sites in CTE stage III closely follows the graded laminar patterns seen in homologous cortico-cortical connections in non-human primates. The Structural Model successfully predicted the laminar distribution of the p-tau neurofibrillary tangles and neurites and their density, based on the relative laminar (dis)similarity between the cortical origin (seed) and each connection site. The findings were validated for generalizability by a computational progression model. By contrast, the early focal perivascular pathology in the sulcal depths followed local columnar connectivity rules. These findings support the general applicability of a theoretical model to unravel the direction and progression of p-tau pathology in human neurodegeneration via a cortico-cortical mechanism. Cortical pathways converging on medial MTL help explain the progressive spread of p-tau pathology from focal cortical sites in early CTE to widespread lateral MTL areas and beyond in later disease stages.

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.

Chronic Traumatic Encephalopathy as the Course of Alzheimer's Disease

This editorial investigates chronic traumatic encephalopathy (CTE) as a course of Alzheimer's disease (AD). CTE is a debilitating neurodegenerative disease that is the result of repeated mild traumatic brain injury (TBI). Many epidemiological studies show that experiencing a TBI in early or middle life is associated with an increased risk of dementia later in life. Chronic traumatic encephalopathy (CTE) and Alzheimer's disease (AD) present a series of similar neuropathological features that were investigated in this work like recombinant tau into filaments or the accumulation and aggregation of Aβ protein. However, these two conditions differ from each other in brain-blood barrier damage. The purpose of this review was to evaluate information about CTE and AD from various articles, focusing especially on new therapeutic possibilities for the improvement in cognitive skills.

Chronic traumatic encephalopathy neuropathologic change in former Australian rugby players

AIMS

We applied the 2021 consensus criteria for both chronic traumatic encephalopathy neuropathological change and traumatic encephalopathy syndrome in a small case series of six former elite-level Australian rugby code players.

METHODS

Neuropathological assessment of these cases was carried out at the Sydney and Victorian Brain Banks. Clinical data were collected via clinical interviews and health questionnaires completed by the participants and/or their next of kin, and neuropsychological testing was conducted with participants who were capable of completing this testing.

RESULTS

All cases exhibited progressive cognitive impairment during life. Chronic traumatic encephalopathy neuropathological change was identified in four out of the six cases. However, coexisting neuropathologies were common, with limbic-predominant age-related TDP-43 encephalopathy and ageing-related tau astrogliopathy seen in all cases, intermediate or high Alzheimer's disease neuropathological change seen in four cases and hippocampal sclerosis seen in two of the six cases.

CONCLUSION

The presence of multiple neuropathologies in these cases complicates clinical diagnostic efforts for traumatic encephalopathy syndrome. It will be important for further clinicopathological studies on larger groups to report all neuropathological comorbidities found in cases diagnosed with either chronic traumatic encephalopathy neuropathological change and/or traumatic encephalopathy syndrome.

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. 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 clinical symptoms observed 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.

Cerebral Cortical Surface Structure and Neural Activation Pattern Among Adolescent Football Players

Importance

Recurring exposure to head impacts in American football has garnered public and scientific attention, yet neurobiological associations in adolescent football players remain unclear.

Objective

To examine cortical structure and neurophysiological characteristics in adolescent football players.

Design, Setting, and Participants

This cohort study included adolescent football players and control athletes (swimming, cross country, and tennis) from 5 high school athletic programs, who were matched with age, sex (male), and school. Neuroimaging assessments were conducted May to July of the 2021 and 2022 seasons. Data were analyzed from February to November 2023.

Exposure

Playing tackle football or noncontact sports.

Main Outcomes and Measures

Structural magnetic resonance imaging (MRI) data were analyzed for cortical thickness, sulcal depth, and gyrification, and cortical surface-based resting state (RS)-functional MRI analyses examined the amplitude of low-frequency fluctuation (ALFF), regional homogeneity (ReHo), and RS-functional connectivity (RS-FC).

Results

Two-hundred seventy-five male participants (205 football players; mean [SD] age, 15.8 [1.2] years; 5 Asian [2.4%], 8 Black or African American [3.9%], and 189 White [92.2%]; 70 control participants; mean [SD] age 15.8 [1.2] years, 4 Asian [5.7], 1 Black or African American [1.4%], and 64 White [91.5%]) were included in this study. Relative to the control group, the football group showed significant cortical thinning, especially in fronto-occipital regions (eg, right precentral gyrus: t = -2.24; P = .01; left superior frontal gyrus: -2.42; P = .002). Elevated cortical thickness in football players was observed in the anterior and posterior cingulate cortex (eg, left posterior cingulate cortex: t = 2.28; P = .01; right caudal anterior cingulate cortex 3.01; P = .001). The football group had greater and deeper sulcal depth than the control groups in the cingulate cortex, precuneus, and precentral gyrus (eg, right inferior parietal lobule: t = 2.20; P = .004; right caudal anterior cingulate cortex: 4.30; P < .001). Significantly lower ALFF was detected in the frontal lobe and cingulate cortex of the football group (t = -3.66 to -4.92; P < .01), whereas elevated ALFF was observed in the occipital regions (calcarine and lingual gyrus, t = 3.20; P < .01). Similar to ALFF, football players exhibited lower ReHo in the precentral gyrus and medial aspects of the brain, such as precuneus, insula, and cingulum, whereas elevated ReHo was clustered in the occipitotemporal regions (t = 3.17; P < .001; to 4.32; P < .01). There was no group difference in RS-FC measures.

Conclusions and Relevance

In this study of adolescent athletes, there was evidence of discernible structural and physiological differences in the brains of adolescent football players compared with their noncontact controls. Many of the affected brain regions were associated with mental health well-being.

p17/C18-ceramide-mediated mitophagy is an endogenous neuroprotective response in preclinical and clinical brain injury

Repeat concussions (or repetitive mild traumatic brain injury [rmTBI]) are complex pathological processes consisting of a primary insult and long-term secondary complications and are also a prerequisite for chronic traumatic encephalopathy (CTE). Recent evidence implies a significant role of autophagy-mediated dysfunctional mitochondrial clearance, mitophagy, in the cascade of secondary deleterious events resulting from TBI. C18-ceramide, a bioactive sphingolipid produced in response to cell stress and damage, and its synthesizing enzyme (CerS1) are precursors to selective stress-mediated mitophagy. A transporter, p17, mediates the trafficking of CerS1, induces C18-ceramide synthesis in the mitochondrial membrane, and acts as an elimination signal in cell survival. Whether p17-mediated mitophagy occurs in the brain and plays a causal role in mitochondrial quality control in secondary disease development after rmTBI are unknown. Using a novel repetitive less-than-mild TBI (rlmTBI) injury paradigm, ablation of mitochondrial p17/C18-ceramide trafficking in p17 knockout (KO) mice results in a loss of C18-ceramide-induced mitophagy, which contributes to susceptibility and recovery from long-term secondary complications associated with rlmTBI. Using a ceramide analog with lipid-selenium conjugate drug, LCL768 restored mitophagy and reduced long-term secondary complications, improving cognitive deficits in rlmTBI-induced p17KO mice. We obtained a significant reduction of p17 expression and a considerable decrease of CerS1 and C18-ceramide levels in cortical mitochondria of CTE human brains compared with age-matched control brains. These data demonstrated that p17/C18-ceramide trafficking is an endogenous neuroprotective mitochondrial stress response following rlmTBI, thus suggesting a novel prospective strategy to interrupt the CTE consequences of concussive TBI.

The spectrum of acute and chronic consequences of neurotrauma in professional and amateur boxing - A call to action is advocated to better understand and prevent this phenomenon

Introduction

Despite changes in regulations, boxing-related injuries and fatalities are still occurring. The numbers available in the literature regarding mortality and long-term consequences may not accurately represent the actual situation. Indeed, the real extent of this phenomenon remains poorly known.

Research question

Delineating the spectrum of acute and chronic consequences of boxing-related traumatic brain injuries (TBI).

Material and methods

Narrative review of the literature concerning acute and chronic boxing-related TBI. Keywords such as mortality, boxing, subdural hematoma were used to search in PubMed and Google scholar. An updated analysis of the Velazquez fatalities collection in boxing was undertaken.

Results

The Velazquez collection includes 2076 fatalities from 1720 to the present with a death rate of 10 athletes per year. More than half of the deaths (N = 1354, 65.2%) occurred after a knock-out, and nearly 75% happened during professional bouts. In Australia, from 1832 to 2020, 163 fatalities were recorded (75% professional). In Japan, from 1952 to 2016, 38 deaths were recorded with a mean age of 23.9 years. Up to 40% of retired professional boxers in the United States were diagnosed with symptoms of chronic brain injury. Clinical dementia is far more prevalent among professional boxers than in amateurs with an incidence of 20%.

Discussion and conclusions

A concerted effort to raise awareness and shed light on boxing-related neuro-trauma is required. Similar considerations can be made for other combat sports or contact sports. A call to action to address this knowledge gap, decrease and prevent this phenomenon is advocated.