Alan Pearce PhD, is Adjunct Professor, Research Fellow in the School of Health (Swinburne Neuroimaging Facility) Swinburne University of Technology, Melbourne, and adjunct Research Manager at the Australian Sports Brain Bank. Supervisors: Professor Frank Mastaglia (Former PhD supervisor)
The effects of non-concussive impacts in contact-sports such as in Australian rules football (ARF... more The effects of non-concussive impacts in contact-sports such as in Australian rules football (ARF) are still largely unexplored. These impacts are often but not always lower in intensity, but occur more frequently than actual concussions. Since non-concussive impacts are often asymptomatic, their significance may be underestimated. Acute or subacute measurement of non-concussive injury is challenging as the pathological response and injury is poorly described. There is therefore a need for a greater understanding of the pathological consequences of exposure. Growing evidence indicates that resting-state functional connectivity (rs-fMRI) changes in the Default Mode Network (DMN) may be an important biomarker that is sensitive to characterize these impacts. In this work, we examined functional connectivity changes within the DMN of ARF players to evaluate its potential as an early biomarker for non-concussive impacts. Based on rs-fMRI, we compare the DMN of 47 sub-elite ARF players (mean age 21.5±2.7 years [SD], males 57%) and 42 age-matched healthy controls (mean age 23.2±2.3 years [SD], males 48%) using Independent Component Analysis (ICA) and Dual Regression. This approach permits an unbiased decomposition of brain activity into networks with principled handling of statistical error. An 83% increase in DMN connectivity (as measured by the Strictly Standardized Mean Difference on values derived from Dual Regression) was observed in ARF players in the left retrosplenial cingulate cortex compared to healthy controls (FDR-corrected p-value from dual regression = 0.03, 95% CI computed via bootstrapping was 58% to 116%). The AUC for distinguishing ARF players from controls was 0.80 (95% CI; [0.71, 0.89]), equating to a PPV of 78% and a NPV of 74%. These results are preliminary; future work could investigate robustness to different random initializations of ICA and validate the findings on an independent testing set, as well as investigate longitudinal changes in ARF players over the course of a playing season.
Aim of the study
Interest continues investigating pathophysiology of athlete cohorts with a histo... more Aim of the study Interest continues investigating pathophysiology of athlete cohorts with a history involving cumulative career exposure of repeated concussion and non-concussion impacts. One area yet to be explored involves the somatosensory system. Using a novel sensorimotor technique, this study measured the somatosensory system in retired contact sport athletes exposed to repetitive neurotrauma.
Materials and Methods Retired athletes (n=85, mean age 48.6 ± 10.6 years, all male) completed a self-report survey on their playing career, number of concussions, and continuing symptoms. Participants completed somatosensory vibrotactile tasks assessing reaction time, amplitude discrimination (sequential, simultaneous), and temporal discrimination (temporal order judgment, duration discrimination). Participants were divided between those reporting persistent symptoms (“symptomatic”, n=63) and those without concerns (“non-symptomatic”, n=22).
Results “Symptomatic” participants scored higher symptom scores compared to the “nonsymptomatic” group (P<0.001). No differences were found between groups for age (P=0.152), number of concussions (P=0.193), total years played (P=0.385), or professional career length (P=0.711). “Symptomatic” group reaction times were slower to the “nonsymptomatic” group (P<0.001). Reaction time variability were greater in the “symptomatic” group (P=0.002). Differences between groups were found for amplitude discrimination (sequential: P=0.031; simultaneous: P=0.036) and temporal order judgment (P=0.032). Significant correlations were found between total symptom scores and all somatosensory tasks. Correlations showed associations between total exposure years with temporal order judgement and reaction time.
Conclusions. This novel study showed altered sensorimotor perception in retired athletes with persistent symptoms. Our data adds to the growing pathophysiological evidence in those who experience repetitive neurotrauma during their playing careers.
As Australia's biggest sports codes come into finals, their lofty talk on protecting players from... more As Australia's biggest sports codes come into finals, their lofty talk on protecting players from concussions will be put to the test.
Aim
Repetitive head impact exposure, from contact and collision sports, are increasingly being at... more Aim Repetitive head impact exposure, from contact and collision sports, are increasingly being attributed to increased risk of neurodegenerative disease in aging athletes. This exploratory study investigated the association of playing career in retired professional contact sport athletes with cortical neurophysiology via transcranial magnetic stimulation (TMS).
Methods Male athletes between the ages of 28-68 years (n=113; mean age [SD] 48.8 [9.7]) who had been retired from professional sport for a minimum of five years were recruited. Cortical excitability was measured using single pulse TMS for motor evoked potentials and paired pulse transcranial magnetic stimulation short-interval intracortical inhibition and long-interval intracortical inhibition. Associations were assessed between transcranial magnetic stimulation measures and concussion history, clinical symptom scores, total career length (including junior to complete retirement), and professional career length (elite competition only).
Results Correlations showed significant associations between motor evoked potentials and clinical symptom reporting (rho: -0.21 – -0.38; P<0.01); and motor evoked potentials and short-interval intracortical inhibition with total career length (rho: 0.26 – -0.33; P<0.01). No significant correlations were observed between single and paired-pulse transcranial magnetic stimulation and professional career length (rho: 0.16 – -0.15), nor the number of concussions (rho: 0.17 – -0.17).
Conclusions This study is the first to report pathophysiological outcomes in a cohort of retired professional athletes associated with total career exposure, rather than professional career exposure or concussion history. TMS assessment could be considered a viable biomarker in future studies of retired athletes suspected with traumatic encephalopathy syndrome.
Attention and awareness regarding concussion injury in Australia has significantly increased in t... more Attention and awareness regarding concussion injury in Australia has significantly increased in the last decade. While most of this increase is due to discussion regarding concussions from sporting endeavours, the majority of concussions are from non-sport environments including motor vehicle crashes, workplace incidents, falls, accidents, assault and intimate partner violence. In all cases hospital Emergency Departments (EDs) are the first point of contact, yet as argued in our Opinion here, there are concerns regarding the consistency of care protocols, due to a number of reasons, as well as management and follow up clinical practices. Our Opinion is to provide a constructive discussion as well as calling for ACEM to support research to provide evidence-based data. Finally, we provide some recommendations that could be implemented immediately to improve clinical practice for presentations of concussion injuries in EDs.
This week, Collingwood AFL player Nathan Murphy announced his retirement, brought on by his concu... more This week, Collingwood AFL player Nathan Murphy announced his retirement, brought on by his concussion history and ongoing issues. The 24-year-old's seemingly sudden retirement, following Angus Brayshaw's in February and a number of other high-profile footballers in recent years, signals a shift in how athletes view brain trauma risks in sport.
Journal of Functional Morphology and Kinesiology, 2024
Sport-related concussions (SRCs) are a mild traumatic brain injury (mTBI) that induces transient ... more Sport-related concussions (SRCs) are a mild traumatic brain injury (mTBI) that induces transient symptoms in athletes. These symptoms provide avenues for developing emerging technologies to diagnose SRCs, in particular ocular and vestibular dysfunction. The following study aims to assess the reliability of visual smooth-pursuit technology (EyeGuide Focus) in amateur fieldsport athletes. A convenience sample of 30 mixed-gender athletes (mean age = 24.89 ± 6.81 years) completed two testing sessions separated by 2-7 days. Participants were tested at rest, free from distraction, and completed a 10 s smooth pursuit while seated. Participants completed 2-4 practice trials before completing three tests at each session. Appropriate difference, reliability, and repeatability tests were performed in Statistical Packages for the Social Sciences. No significant difference existed between the time points (p > 0.05). The reliability between sessions was poor (ICC = 0.24; 95% CI = 0.03-0.42), and the mean coefficients of variation were 20% and 21% for each session, indicating poor repeatability. However, the implementation of practice trials did prevent the familiarization effects that are evident in the previous literature (p > 0.05). The within-session reliability of EyeGuide Focus has varied from poor (ICC ≤ 0.50) to good (ICC = 0.75-0.90) in the previous literature, indicating the fact that greater research is required before this tool can be implemented in applied settings.
This study explored professional male Australian rules football players leaving the Australian Fo... more This study explored professional male Australian rules football players leaving the Australian Football League (AFL), either from retirement or from deselected from their team. Identified athletes (n = 425) transitioning from the AFL competition from years 2019 to 2021 were invited to participate in an anonymous online survey with 60% completing the survey. Using scaled-response questions, responses were compared between groups across a number of areas including their experience of leaving, athlete identity, the influence of sport in their daily life, psychological flourishing, financial confidence, social relationships, and future career preparations. Results showed deselected players (n = 152), compared to retired players (n = 56), reported shorter career spans, and poorer perception of their club's handling of the transition process (p < 0.001). Compared to retired players, deselected players reported stronger identity attachment to sport, less confidence in their financial capabilities, and career outside football (all p < 0.05). Conversely retired players, compared to deselected players, showed stronger psychological flourishing. Correlations showed that retired players were more confidence in their finances, reported greater psychological flourishing, and lower attachment to an athletic identity (all p ≤ 0.05). The results of this study suggest that as deselected players expressed poorer perception of club's handling of the transition process the role of AFL club staff could improve the transition process in in preparation for life outside of professional sport.
International concern continues regarding the association between the long-term neurophysiologic ... more International concern continues regarding the association between the long-term neurophysiologic changes from repetitive neurotrauma associated with contact and collision sports. This study describes corticomotor changes in retired contact/collision sport athletes and controls, between the ages of 30 and 70 years. Retired athletes (n=152; 49.1±8.5 years) and controls (n=72; 47.8±9.5 years) were assessed using single and paired-pulse transcranial
magnetic stimulation (TMS) for active motor threshold (aMT), motor evoked potential and cortical silent period duration (expressed as MEP:cSP ratio), and short- and long-interval intracortical inhibition (SICI and LICI). Motor threshold, MEP:cSP, SICI and LICI for both groups were correlated across age. Controls showed significant moderate correlations for MEP:cSP ratios at 130% (rho=0.48, p<0.001), 150% (rho=0.49, p<0.001) and 170% aMT (rho=0.42; p<0.001) and significant small negative correlation for SICI (rho=-0.27; p=0.030), and moderate negative correlation for LICI (rho=-0.43; p<0.001). Group-wise correlation analysis comparisons showed significant correlation differences between groups for 130% (p=0.016) and 150% aMT (p=0.009), specifically showing retired athletes were displaying increased corticomotor inhibition. while previous studies have focussed studies on older athletes (>50 years), this study is the first to characterize corticomotor differences between retired athletes and controls across the lifespan. These results, demonstrating pathophysiological differences in retired athletes across the lifespan, provide a foundation to utilise evoked potentials as a prodromal marker in supplementing neurological assessment for traumatic encephalopathy syndrome associated with contact/collision sport athletes that is currently lacking physiological biomarkers.
Background: Transcranial Alternating Current Stimulation (tACS) employs low-intensity sinusoidal ... more Background: Transcranial Alternating Current Stimulation (tACS) employs low-intensity sinusoidal currents to influence cortical plasticity and motor function. Despite extensive research, inconsistent results require a comprehensive review of tACS efficacy. Objective: This study systematically assesses tACS effects on corticospinal and intracortical excitability, and motor function over the motor cortex (M1), focusing on alpha, beta, and gamma frequencies. Methods: Relevant studies were identified through database searches and citations were tracked until July 10, 2023. The methodological quality of the included studies (29) was evaluated by Downs and Black. Data synthesis involved meta-analysis (n = 25) and best evidence synthesis (n = 5). Results: Meta-analysis revealed that alpha and beta tACS with intensities > 1 mA and tACS with individualised alpha frequency (IAF) increased corticospinal excitability (CSE). tACS over M1 improved motor function, irrespective of stimulation frequency and intensity. Sub-analysis showed that alpha and beta tACS with an intensity ≤ 1 mA led to improved motor function, while gamma tACS at 2 mA enhanced motor function. Additionally, beta tACS at a fixed frequency of 20 Hz, as well as both low gamma (30-55) and high gamma (55-80) tACS, resulted in improved motor function. A stimulation duration of 20 min led to improvements in both CSE and motor function, and tACS with electrode sizes smaller than 35 cm 2 and an electrode montage over M1-supraorbital region (SOR) were found to enhance motor function. Notably, both online and offline tACS improved motor function, regardless of stimulation factors. Conclusion: tACS modulates CSE and improves motor function, with outcomes dependent on stimulation parameters and timing.
This study aimed to quantitatively investigate and report the biomechanical characteristics of co... more This study aimed to quantitatively investigate and report the biomechanical characteristics of concussive and sub-concussive impacts in youth sports. A systematic search was conducted in September 2022 to identify biomechanical impact studies in athletes ≤18 years of age. Twenty-six studies met the inclusion criteria for quantitative synthesis and analysis. DerSimonian Laird random effects model was used to pool data across the included studies. The pooled estimate of mean peak linear and rotational acceleration of concussive impacts in male youth athletes was 85.56 g (95% CI 69.34-101.79) and 4505.58 rad/s 2 (95% CI 2870.28-6140.98), respectively. The pooled estimate of mean peak linear and rotational acceleration of sub-concussive impacts in youth athletes was 22.89 g (95% CI 20.69-25.08) and 1290.13 rad/s 2 (95%CI 1050.71-1529.55), respectively. A male vs female analysis in sub-concussive impacts revealed higher linear and rotational acceleration in males and females respectively. This is the first study to report on impact data in both sexes of youth athletes. Disparity in kinematic impact values suggests future research should aim for standardised measures to reduce heterogeneity in data. Despite this, the data reveals notable impact data that youth athletes are exposed to, suggesting modifications may be required to reduce long term neurological risks.
Background: Functional gastrointestinal disorders (FGIDs) are common, difficult-to-manage conditi... more Background: Functional gastrointestinal disorders (FGIDs) are common, difficult-to-manage conditions. Probiotics are emerging as a dietary component that influence gastrointestinal (GI) health. We conducted a double-blinded randomised controlled trial of a proprietary strain of deactivated Bacillus subtilis (BG01-4™) high in branched-chain fatty acids (BCFA) to treat self-reported FGID. Methods: Participants (n = 67) completed a four-week intervention of BG01-4™ (n = 34) or placebo (n = 33). The Gastrointestinal Symptom Rating Scale (GSRS) served as the outcome measure, collected prior to, at two weeks, and at four weeks after completion of the intervention. Results: At four weeks, one of three primary outcomes, constipation in the experimental group, was improved by 33% compared to placebo (15%); both other primary outcomes, Total GSRS and diarrhoea, were significantly improved in both the experimental and placebo groups (32%/26% and 20%/22%, respectively). The pre-planned secondary outcome, indigestion, was improved at four weeks (32%) but compared to the placebo (21%) was not significant (p = 0.079). Exploratory analysis, however, revealed that clusters for constipation (18% improvement, p < 0.001), indigestion (11% improvement, p = 0.04), and dyspepsia (10% improvement, p = 0.04) were significantly improved in the intervention group compared to the placebo. Conclusions: These initial findings suggest that in people with self-reported FGID, BG01-4™improves specific symptoms of constipation and related GI dysfunction. Longer-term confirmatory studies for this intervention are warranted. Trial registration: This study was registered prospectively (25 October 2021) at the Australian New Zealand Clinical Trials Registry (ACTRN12621001441808p).
Mild traumatic brain injury (mTBI) represents a significant burden for individuals, economies, an... more Mild traumatic brain injury (mTBI) represents a significant burden for individuals, economies, and healthcare systems worldwide. Recovery protocols focus on medication and physiotherapybased interventions. Animal studies have shown that antioxidants, branched-chain amino acids and Omega-3 fatty acids may improve neurophysiological outcomes after TBI. However, there appears to be a paucity of nutritional interventions in humans with chronic (>1 month) symptomology post-mTBI. This systematic literature review aimed to consolidate evidence for nutrition and dietaryrelated interventions in humans with chronic mTBI. The review was registered with the International Prospective Register of Systematic Reviews (PROSPERO; CRD42021277780) and conducted following the Preferred Reporting for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Three reviewers searched five databases (PubMed/MEDLINE, Web of Science, SPORTDiscus, CINAHL Complete and Cochrane), which yielded 6164 studies. Nine studies met the inclusion criteria. The main finding was the lack of interventions conducted to date, and a quality assessment of the included studies was found to be fair to good. Due to heterogeneity, a meta-analysis was not feasible. The six nutrition areas identified (omega-3 fatty acids, melatonin, Enzogenol®, MLC901, ketogenic diet and phytocannabinoids) were safe and well-tolerated. It was found that these nutritional interventions may improve cognitive failures, sleep disturbances, anxiety, physical disability, systolic blood pressure volume and sport concussion assessment tool scores following mTBI. Potential areas of improvement identified for future studies included blinding, reporting compliance, and controlling for confounders. In conclusion, further research of higher quality is needed to investigate the role of nutrition in recovery from mTBI to reduce the burden of chronic outcomes following mTBI.
The Boston University CTE Center today reported the results of the largest-ever study of chronic ... more The Boston University CTE Center today reported the results of the largest-ever study of chronic traumatic encephalopathy (CTE) in young athletes. The study, examining autopsied tissue, found signs of CTE in 63 out of 152 young athlete brains. The subjects of the study competed in youth, high school and college competitions, and all died before the age of 30.
Researchers at the Australian Sports Brain Bank have today reported the world’s first diagnosis o... more Researchers at the Australian Sports Brain Bank have today reported the world’s first diagnosis of chronic traumatic encephalopathy (CTE) in a female athlete.
Journal of Functional Morphology and Kinesiology, 2019
Mild traumatic brain injury (mTBI) is the most common brain injury, seen in sports, fall, vehicle... more Mild traumatic brain injury (mTBI) is the most common brain injury, seen in sports, fall, vehicle, or workplace injuries. Concussion is the most common type of mTBI. Assessment of impairments from concussion is evolving, with oculomotor testing suggested as a key component in a multimodality diagnostic protocol. The aim of this study was to evaluate the reliability of one eye-tracking system, the EyeGuide Focus. A group of 75 healthy adolescent and adult participants (adolescents: n = 28; female = 11, male = 17, mean age 16.5 ± 1.4 years; adults n = 47; female = 22; male = 25, mean age 26.7 ± 7.0 years) completed three repetitions of the EyeGuide Focus within one session. Intraclass correlation coefficient (ICC) analysis showed the EyeGuide Focus had overall good reliability (ICC 0.79, 95%CI: 0.70, 0.86). However, a familiarization effect showing improvements in subsequent trials 2 (9.7%) and 3 (8.1%) was noticeable in both cohorts (p < 0.001) with adolescent participants showing greater familiarization effects than adults (21.7% vs. 13.1%). No differences were observed between sexes (p = 0.69). Overall, this is the first study to address the concern regarding a lack of published reliability studies for the EyeGuide Focus. Results showed good reliability, suggesting that oculomotor pursuits should be part of a multimodality assessment protocol, but the observation of familiarization effects suggests that smooth-pursuit testing using this device has the potential to provide a biologically-based interpretation of the maturation of the oculomotor system, as well as its relationship to multiple brain regions in both health and injury.
Background Functional gastrointestinal disorders (FGIDs) are a common, di cult to manage conditio... more Background Functional gastrointestinal disorders (FGIDs) are a common, di cult to manage condition. Branched chain fatty acids are emerging as a dietary component that in uence gastrointestinal (GI) health. We conducted a double blinded randomized controlled trial of a proprietary strain of deactivated Bacillus subtilis (BG01-4™) that produce branched change fatty acids (BCFA) in the lower GI tract to treat self-reported FGID. Methods Participants (n = 67) completed a four-week intervention of BG01-4™ (n = 34) or placebo (n = 33). The Gastrointestinal Symptom Rating Scale (GSRS) served as the outcome measure, collected prior to, at two-weeks, and at the four-week completion of the intervention. Results At four weeks one of three primary outcomes, constipation in the experimental group, was improved compared to placebo; both other primary outcomes Total GCRS and diarrhoea, were signi cantly improved in both experimental and placebo groups. The pre-planned secondary outcome indigestion was improved at four weeks compared to entry with trend to signi cance compared to placebo (p = 0.079). Exploratory analysis revealed clusters for constipation (18% improvement, p < 0.001), indigestion (11% improvement, p = 0.04), and dyspepsia (10% improvement, p = 0.04), were signi cantly improved in the intervention group compared to the placebo. Conclusions These initial ndings suggest that in people with self-reported FGID, BG01-4™ improves speci c symptoms of constipation and related GI dysfunction, potentially mediated via synthesis of BCFA. Longer term con rmatory studies for this intervention are warranted.
The effects of non-concussive impacts in contact-sports such as in Australian rules football (ARF... more The effects of non-concussive impacts in contact-sports such as in Australian rules football (ARF) are still largely unexplored. These impacts are often but not always lower in intensity, but occur more frequently than actual concussions. Since non-concussive impacts are often asymptomatic, their significance may be underestimated. Acute or subacute measurement of non-concussive injury is challenging as the pathological response and injury is poorly described. There is therefore a need for a greater understanding of the pathological consequences of exposure. Growing evidence indicates that resting-state functional connectivity (rs-fMRI) changes in the Default Mode Network (DMN) may be an important biomarker that is sensitive to characterize these impacts. In this work, we examined functional connectivity changes within the DMN of ARF players to evaluate its potential as an early biomarker for non-concussive impacts. Based on rs-fMRI, we compare the DMN of 47 sub-elite ARF players (mean age 21.5±2.7 years [SD], males 57%) and 42 age-matched healthy controls (mean age 23.2±2.3 years [SD], males 48%) using Independent Component Analysis (ICA) and Dual Regression. This approach permits an unbiased decomposition of brain activity into networks with principled handling of statistical error. An 83% increase in DMN connectivity (as measured by the Strictly Standardized Mean Difference on values derived from Dual Regression) was observed in ARF players in the left retrosplenial cingulate cortex compared to healthy controls (FDR-corrected p-value from dual regression = 0.03, 95% CI computed via bootstrapping was 58% to 116%). The AUC for distinguishing ARF players from controls was 0.80 (95% CI; [0.71, 0.89]), equating to a PPV of 78% and a NPV of 74%. These results are preliminary; future work could investigate robustness to different random initializations of ICA and validate the findings on an independent testing set, as well as investigate longitudinal changes in ARF players over the course of a playing season.
Aim of the study
Interest continues investigating pathophysiology of athlete cohorts with a histo... more Aim of the study Interest continues investigating pathophysiology of athlete cohorts with a history involving cumulative career exposure of repeated concussion and non-concussion impacts. One area yet to be explored involves the somatosensory system. Using a novel sensorimotor technique, this study measured the somatosensory system in retired contact sport athletes exposed to repetitive neurotrauma.
Materials and Methods Retired athletes (n=85, mean age 48.6 ± 10.6 years, all male) completed a self-report survey on their playing career, number of concussions, and continuing symptoms. Participants completed somatosensory vibrotactile tasks assessing reaction time, amplitude discrimination (sequential, simultaneous), and temporal discrimination (temporal order judgment, duration discrimination). Participants were divided between those reporting persistent symptoms (“symptomatic”, n=63) and those without concerns (“non-symptomatic”, n=22).
Results “Symptomatic” participants scored higher symptom scores compared to the “nonsymptomatic” group (P<0.001). No differences were found between groups for age (P=0.152), number of concussions (P=0.193), total years played (P=0.385), or professional career length (P=0.711). “Symptomatic” group reaction times were slower to the “nonsymptomatic” group (P<0.001). Reaction time variability were greater in the “symptomatic” group (P=0.002). Differences between groups were found for amplitude discrimination (sequential: P=0.031; simultaneous: P=0.036) and temporal order judgment (P=0.032). Significant correlations were found between total symptom scores and all somatosensory tasks. Correlations showed associations between total exposure years with temporal order judgement and reaction time.
Conclusions. This novel study showed altered sensorimotor perception in retired athletes with persistent symptoms. Our data adds to the growing pathophysiological evidence in those who experience repetitive neurotrauma during their playing careers.
As Australia's biggest sports codes come into finals, their lofty talk on protecting players from... more As Australia's biggest sports codes come into finals, their lofty talk on protecting players from concussions will be put to the test.
Aim
Repetitive head impact exposure, from contact and collision sports, are increasingly being at... more Aim Repetitive head impact exposure, from contact and collision sports, are increasingly being attributed to increased risk of neurodegenerative disease in aging athletes. This exploratory study investigated the association of playing career in retired professional contact sport athletes with cortical neurophysiology via transcranial magnetic stimulation (TMS).
Methods Male athletes between the ages of 28-68 years (n=113; mean age [SD] 48.8 [9.7]) who had been retired from professional sport for a minimum of five years were recruited. Cortical excitability was measured using single pulse TMS for motor evoked potentials and paired pulse transcranial magnetic stimulation short-interval intracortical inhibition and long-interval intracortical inhibition. Associations were assessed between transcranial magnetic stimulation measures and concussion history, clinical symptom scores, total career length (including junior to complete retirement), and professional career length (elite competition only).
Results Correlations showed significant associations between motor evoked potentials and clinical symptom reporting (rho: -0.21 – -0.38; P<0.01); and motor evoked potentials and short-interval intracortical inhibition with total career length (rho: 0.26 – -0.33; P<0.01). No significant correlations were observed between single and paired-pulse transcranial magnetic stimulation and professional career length (rho: 0.16 – -0.15), nor the number of concussions (rho: 0.17 – -0.17).
Conclusions This study is the first to report pathophysiological outcomes in a cohort of retired professional athletes associated with total career exposure, rather than professional career exposure or concussion history. TMS assessment could be considered a viable biomarker in future studies of retired athletes suspected with traumatic encephalopathy syndrome.
Attention and awareness regarding concussion injury in Australia has significantly increased in t... more Attention and awareness regarding concussion injury in Australia has significantly increased in the last decade. While most of this increase is due to discussion regarding concussions from sporting endeavours, the majority of concussions are from non-sport environments including motor vehicle crashes, workplace incidents, falls, accidents, assault and intimate partner violence. In all cases hospital Emergency Departments (EDs) are the first point of contact, yet as argued in our Opinion here, there are concerns regarding the consistency of care protocols, due to a number of reasons, as well as management and follow up clinical practices. Our Opinion is to provide a constructive discussion as well as calling for ACEM to support research to provide evidence-based data. Finally, we provide some recommendations that could be implemented immediately to improve clinical practice for presentations of concussion injuries in EDs.
This week, Collingwood AFL player Nathan Murphy announced his retirement, brought on by his concu... more This week, Collingwood AFL player Nathan Murphy announced his retirement, brought on by his concussion history and ongoing issues. The 24-year-old's seemingly sudden retirement, following Angus Brayshaw's in February and a number of other high-profile footballers in recent years, signals a shift in how athletes view brain trauma risks in sport.
Journal of Functional Morphology and Kinesiology, 2024
Sport-related concussions (SRCs) are a mild traumatic brain injury (mTBI) that induces transient ... more Sport-related concussions (SRCs) are a mild traumatic brain injury (mTBI) that induces transient symptoms in athletes. These symptoms provide avenues for developing emerging technologies to diagnose SRCs, in particular ocular and vestibular dysfunction. The following study aims to assess the reliability of visual smooth-pursuit technology (EyeGuide Focus) in amateur fieldsport athletes. A convenience sample of 30 mixed-gender athletes (mean age = 24.89 ± 6.81 years) completed two testing sessions separated by 2-7 days. Participants were tested at rest, free from distraction, and completed a 10 s smooth pursuit while seated. Participants completed 2-4 practice trials before completing three tests at each session. Appropriate difference, reliability, and repeatability tests were performed in Statistical Packages for the Social Sciences. No significant difference existed between the time points (p > 0.05). The reliability between sessions was poor (ICC = 0.24; 95% CI = 0.03-0.42), and the mean coefficients of variation were 20% and 21% for each session, indicating poor repeatability. However, the implementation of practice trials did prevent the familiarization effects that are evident in the previous literature (p > 0.05). The within-session reliability of EyeGuide Focus has varied from poor (ICC ≤ 0.50) to good (ICC = 0.75-0.90) in the previous literature, indicating the fact that greater research is required before this tool can be implemented in applied settings.
This study explored professional male Australian rules football players leaving the Australian Fo... more This study explored professional male Australian rules football players leaving the Australian Football League (AFL), either from retirement or from deselected from their team. Identified athletes (n = 425) transitioning from the AFL competition from years 2019 to 2021 were invited to participate in an anonymous online survey with 60% completing the survey. Using scaled-response questions, responses were compared between groups across a number of areas including their experience of leaving, athlete identity, the influence of sport in their daily life, psychological flourishing, financial confidence, social relationships, and future career preparations. Results showed deselected players (n = 152), compared to retired players (n = 56), reported shorter career spans, and poorer perception of their club's handling of the transition process (p < 0.001). Compared to retired players, deselected players reported stronger identity attachment to sport, less confidence in their financial capabilities, and career outside football (all p < 0.05). Conversely retired players, compared to deselected players, showed stronger psychological flourishing. Correlations showed that retired players were more confidence in their finances, reported greater psychological flourishing, and lower attachment to an athletic identity (all p ≤ 0.05). The results of this study suggest that as deselected players expressed poorer perception of club's handling of the transition process the role of AFL club staff could improve the transition process in in preparation for life outside of professional sport.
International concern continues regarding the association between the long-term neurophysiologic ... more International concern continues regarding the association between the long-term neurophysiologic changes from repetitive neurotrauma associated with contact and collision sports. This study describes corticomotor changes in retired contact/collision sport athletes and controls, between the ages of 30 and 70 years. Retired athletes (n=152; 49.1±8.5 years) and controls (n=72; 47.8±9.5 years) were assessed using single and paired-pulse transcranial
magnetic stimulation (TMS) for active motor threshold (aMT), motor evoked potential and cortical silent period duration (expressed as MEP:cSP ratio), and short- and long-interval intracortical inhibition (SICI and LICI). Motor threshold, MEP:cSP, SICI and LICI for both groups were correlated across age. Controls showed significant moderate correlations for MEP:cSP ratios at 130% (rho=0.48, p<0.001), 150% (rho=0.49, p<0.001) and 170% aMT (rho=0.42; p<0.001) and significant small negative correlation for SICI (rho=-0.27; p=0.030), and moderate negative correlation for LICI (rho=-0.43; p<0.001). Group-wise correlation analysis comparisons showed significant correlation differences between groups for 130% (p=0.016) and 150% aMT (p=0.009), specifically showing retired athletes were displaying increased corticomotor inhibition. while previous studies have focussed studies on older athletes (>50 years), this study is the first to characterize corticomotor differences between retired athletes and controls across the lifespan. These results, demonstrating pathophysiological differences in retired athletes across the lifespan, provide a foundation to utilise evoked potentials as a prodromal marker in supplementing neurological assessment for traumatic encephalopathy syndrome associated with contact/collision sport athletes that is currently lacking physiological biomarkers.
Background: Transcranial Alternating Current Stimulation (tACS) employs low-intensity sinusoidal ... more Background: Transcranial Alternating Current Stimulation (tACS) employs low-intensity sinusoidal currents to influence cortical plasticity and motor function. Despite extensive research, inconsistent results require a comprehensive review of tACS efficacy. Objective: This study systematically assesses tACS effects on corticospinal and intracortical excitability, and motor function over the motor cortex (M1), focusing on alpha, beta, and gamma frequencies. Methods: Relevant studies were identified through database searches and citations were tracked until July 10, 2023. The methodological quality of the included studies (29) was evaluated by Downs and Black. Data synthesis involved meta-analysis (n = 25) and best evidence synthesis (n = 5). Results: Meta-analysis revealed that alpha and beta tACS with intensities > 1 mA and tACS with individualised alpha frequency (IAF) increased corticospinal excitability (CSE). tACS over M1 improved motor function, irrespective of stimulation frequency and intensity. Sub-analysis showed that alpha and beta tACS with an intensity ≤ 1 mA led to improved motor function, while gamma tACS at 2 mA enhanced motor function. Additionally, beta tACS at a fixed frequency of 20 Hz, as well as both low gamma (30-55) and high gamma (55-80) tACS, resulted in improved motor function. A stimulation duration of 20 min led to improvements in both CSE and motor function, and tACS with electrode sizes smaller than 35 cm 2 and an electrode montage over M1-supraorbital region (SOR) were found to enhance motor function. Notably, both online and offline tACS improved motor function, regardless of stimulation factors. Conclusion: tACS modulates CSE and improves motor function, with outcomes dependent on stimulation parameters and timing.
This study aimed to quantitatively investigate and report the biomechanical characteristics of co... more This study aimed to quantitatively investigate and report the biomechanical characteristics of concussive and sub-concussive impacts in youth sports. A systematic search was conducted in September 2022 to identify biomechanical impact studies in athletes ≤18 years of age. Twenty-six studies met the inclusion criteria for quantitative synthesis and analysis. DerSimonian Laird random effects model was used to pool data across the included studies. The pooled estimate of mean peak linear and rotational acceleration of concussive impacts in male youth athletes was 85.56 g (95% CI 69.34-101.79) and 4505.58 rad/s 2 (95% CI 2870.28-6140.98), respectively. The pooled estimate of mean peak linear and rotational acceleration of sub-concussive impacts in youth athletes was 22.89 g (95% CI 20.69-25.08) and 1290.13 rad/s 2 (95%CI 1050.71-1529.55), respectively. A male vs female analysis in sub-concussive impacts revealed higher linear and rotational acceleration in males and females respectively. This is the first study to report on impact data in both sexes of youth athletes. Disparity in kinematic impact values suggests future research should aim for standardised measures to reduce heterogeneity in data. Despite this, the data reveals notable impact data that youth athletes are exposed to, suggesting modifications may be required to reduce long term neurological risks.
Background: Functional gastrointestinal disorders (FGIDs) are common, difficult-to-manage conditi... more Background: Functional gastrointestinal disorders (FGIDs) are common, difficult-to-manage conditions. Probiotics are emerging as a dietary component that influence gastrointestinal (GI) health. We conducted a double-blinded randomised controlled trial of a proprietary strain of deactivated Bacillus subtilis (BG01-4™) high in branched-chain fatty acids (BCFA) to treat self-reported FGID. Methods: Participants (n = 67) completed a four-week intervention of BG01-4™ (n = 34) or placebo (n = 33). The Gastrointestinal Symptom Rating Scale (GSRS) served as the outcome measure, collected prior to, at two weeks, and at four weeks after completion of the intervention. Results: At four weeks, one of three primary outcomes, constipation in the experimental group, was improved by 33% compared to placebo (15%); both other primary outcomes, Total GSRS and diarrhoea, were significantly improved in both the experimental and placebo groups (32%/26% and 20%/22%, respectively). The pre-planned secondary outcome, indigestion, was improved at four weeks (32%) but compared to the placebo (21%) was not significant (p = 0.079). Exploratory analysis, however, revealed that clusters for constipation (18% improvement, p < 0.001), indigestion (11% improvement, p = 0.04), and dyspepsia (10% improvement, p = 0.04) were significantly improved in the intervention group compared to the placebo. Conclusions: These initial findings suggest that in people with self-reported FGID, BG01-4™improves specific symptoms of constipation and related GI dysfunction. Longer-term confirmatory studies for this intervention are warranted. Trial registration: This study was registered prospectively (25 October 2021) at the Australian New Zealand Clinical Trials Registry (ACTRN12621001441808p).
Mild traumatic brain injury (mTBI) represents a significant burden for individuals, economies, an... more Mild traumatic brain injury (mTBI) represents a significant burden for individuals, economies, and healthcare systems worldwide. Recovery protocols focus on medication and physiotherapybased interventions. Animal studies have shown that antioxidants, branched-chain amino acids and Omega-3 fatty acids may improve neurophysiological outcomes after TBI. However, there appears to be a paucity of nutritional interventions in humans with chronic (>1 month) symptomology post-mTBI. This systematic literature review aimed to consolidate evidence for nutrition and dietaryrelated interventions in humans with chronic mTBI. The review was registered with the International Prospective Register of Systematic Reviews (PROSPERO; CRD42021277780) and conducted following the Preferred Reporting for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Three reviewers searched five databases (PubMed/MEDLINE, Web of Science, SPORTDiscus, CINAHL Complete and Cochrane), which yielded 6164 studies. Nine studies met the inclusion criteria. The main finding was the lack of interventions conducted to date, and a quality assessment of the included studies was found to be fair to good. Due to heterogeneity, a meta-analysis was not feasible. The six nutrition areas identified (omega-3 fatty acids, melatonin, Enzogenol®, MLC901, ketogenic diet and phytocannabinoids) were safe and well-tolerated. It was found that these nutritional interventions may improve cognitive failures, sleep disturbances, anxiety, physical disability, systolic blood pressure volume and sport concussion assessment tool scores following mTBI. Potential areas of improvement identified for future studies included blinding, reporting compliance, and controlling for confounders. In conclusion, further research of higher quality is needed to investigate the role of nutrition in recovery from mTBI to reduce the burden of chronic outcomes following mTBI.
The Boston University CTE Center today reported the results of the largest-ever study of chronic ... more The Boston University CTE Center today reported the results of the largest-ever study of chronic traumatic encephalopathy (CTE) in young athletes. The study, examining autopsied tissue, found signs of CTE in 63 out of 152 young athlete brains. The subjects of the study competed in youth, high school and college competitions, and all died before the age of 30.
Researchers at the Australian Sports Brain Bank have today reported the world’s first diagnosis o... more Researchers at the Australian Sports Brain Bank have today reported the world’s first diagnosis of chronic traumatic encephalopathy (CTE) in a female athlete.
Journal of Functional Morphology and Kinesiology, 2019
Mild traumatic brain injury (mTBI) is the most common brain injury, seen in sports, fall, vehicle... more Mild traumatic brain injury (mTBI) is the most common brain injury, seen in sports, fall, vehicle, or workplace injuries. Concussion is the most common type of mTBI. Assessment of impairments from concussion is evolving, with oculomotor testing suggested as a key component in a multimodality diagnostic protocol. The aim of this study was to evaluate the reliability of one eye-tracking system, the EyeGuide Focus. A group of 75 healthy adolescent and adult participants (adolescents: n = 28; female = 11, male = 17, mean age 16.5 ± 1.4 years; adults n = 47; female = 22; male = 25, mean age 26.7 ± 7.0 years) completed three repetitions of the EyeGuide Focus within one session. Intraclass correlation coefficient (ICC) analysis showed the EyeGuide Focus had overall good reliability (ICC 0.79, 95%CI: 0.70, 0.86). However, a familiarization effect showing improvements in subsequent trials 2 (9.7%) and 3 (8.1%) was noticeable in both cohorts (p < 0.001) with adolescent participants showing greater familiarization effects than adults (21.7% vs. 13.1%). No differences were observed between sexes (p = 0.69). Overall, this is the first study to address the concern regarding a lack of published reliability studies for the EyeGuide Focus. Results showed good reliability, suggesting that oculomotor pursuits should be part of a multimodality assessment protocol, but the observation of familiarization effects suggests that smooth-pursuit testing using this device has the potential to provide a biologically-based interpretation of the maturation of the oculomotor system, as well as its relationship to multiple brain regions in both health and injury.
Background Functional gastrointestinal disorders (FGIDs) are a common, di cult to manage conditio... more Background Functional gastrointestinal disorders (FGIDs) are a common, di cult to manage condition. Branched chain fatty acids are emerging as a dietary component that in uence gastrointestinal (GI) health. We conducted a double blinded randomized controlled trial of a proprietary strain of deactivated Bacillus subtilis (BG01-4™) that produce branched change fatty acids (BCFA) in the lower GI tract to treat self-reported FGID. Methods Participants (n = 67) completed a four-week intervention of BG01-4™ (n = 34) or placebo (n = 33). The Gastrointestinal Symptom Rating Scale (GSRS) served as the outcome measure, collected prior to, at two-weeks, and at the four-week completion of the intervention. Results At four weeks one of three primary outcomes, constipation in the experimental group, was improved compared to placebo; both other primary outcomes Total GCRS and diarrhoea, were signi cantly improved in both experimental and placebo groups. The pre-planned secondary outcome indigestion was improved at four weeks compared to entry with trend to signi cance compared to placebo (p = 0.079). Exploratory analysis revealed clusters for constipation (18% improvement, p < 0.001), indigestion (11% improvement, p = 0.04), and dyspepsia (10% improvement, p = 0.04), were signi cantly improved in the intervention group compared to the placebo. Conclusions These initial ndings suggest that in people with self-reported FGID, BG01-4™ improves speci c symptoms of constipation and related GI dysfunction, potentially mediated via synthesis of BCFA. Longer term con rmatory studies for this intervention are warranted.
This chapter will discuss the applications of the motor evoked potential (MEP) waveform across a ... more This chapter will discuss the applications of the motor evoked potential (MEP) waveform across a range of diverse research areas. Following a brief outline of the measureable components of the MEP, the chapter will present the various areas of research that TMS has been used to understand the integrity of the central nervous system and the corticomotor pathway. The areas that will be discussed include experimental studies investigating the effects of varying pharmacological agents, and the effect of neuromodulation techniques, such as repetitive transcranial magnetic stimulation and transcranial direct current stimulation. The chapter will then present studies using the MEP in a variety of applied research including clinical disease and brain injury, skill acquisition and expertise; as well as exercise science research of warming up, strength training and exercise fatigue and recovery. Collectively these studies suggest that the MEP waveform, when applied in context, can provide useful information regarding the neural and neuromuscular mechanisms across a wide variety of research areas.
There has been increasing growing public concern regarding the association of sports concussion o... more There has been increasing growing public concern regarding the association of sports concussion on brain health in later life. Emerging evidence suggests that repetitive head impacts experienced in contact sports, may contribute to either chronic neurological impairments later in life, or neurodegenerative disease. While the majority of the research to date has focused or neuroimaging techniques, such as magnetic resonance imaging or computed tomography scanning; or functional outcomes, such as cognitive deficiencies, mood disorders, or neurodegenerative conditions, relatively less research has focused on neurophysiological abnormalities that may provide the mechanistic evidence for brain function decline and chronic neurological impairments. The aim of this chapter is to present recent research to illustrate chronic neurophysiological changes in those with a history of concussion. Specifically this chapter will summarize recent studies employing techniques such as electroencephalography (EEG), magnetoencephalography (MEG), and transcranial magnetic stimulation (TMS). These studies utilize event related potentials that have demonstrated good evidence of persistent functional injury. The chapter will discuss the advantages of using these techniques, and their ability to quantify functional decline in otherwise healthy retired athletes with a history of repeated head injury. Finally, the chapter will conclude on how these techniques can be utilized, co-registering with modalities such as advanced neuroimaging in the clinical assessment of older individuals with a history of concussion.
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significance may be underestimated. Acute or subacute measurement of non-concussive injury is challenging as the pathological response and injury is poorly described. There is therefore a need for a greater understanding of the pathological consequences of exposure. Growing evidence indicates that resting-state functional connectivity (rs-fMRI) changes in the Default Mode Network (DMN) may be an important biomarker that is sensitive to characterize these impacts. In this work, we examined functional connectivity changes within the DMN of ARF players to evaluate its potential as an early biomarker for non-concussive impacts. Based on rs-fMRI, we compare the DMN of 47 sub-elite ARF players (mean
age 21.5±2.7 years [SD], males 57%) and 42 age-matched healthy controls (mean age 23.2±2.3 years [SD], males 48%) using Independent Component Analysis (ICA) and Dual Regression. This approach permits an unbiased decomposition of brain activity into networks with principled handling of statistical error. An 83% increase in DMN connectivity (as measured by the Strictly Standardized Mean Difference on values derived from Dual Regression) was observed in ARF players in the left retrosplenial cingulate cortex compared to healthy controls (FDR-corrected p-value from dual regression = 0.03, 95% CI computed via bootstrapping was 58% to 116%). The AUC for distinguishing ARF players from controls was 0.80 (95% CI; [0.71, 0.89]), equating to a PPV of 78% and a NPV of 74%. These results are preliminary; future work could investigate robustness to different random initializations of ICA and validate the findings on an independent testing set, as well as investigate longitudinal changes in ARF players over the course of a playing season.
Interest continues investigating pathophysiology of athlete cohorts with a history involving cumulative career exposure of repeated concussion and non-concussion impacts. One area yet to be explored involves the somatosensory system. Using a novel sensorimotor technique, this study measured the somatosensory system in retired contact sport athletes exposed to repetitive neurotrauma.
Materials and Methods
Retired athletes (n=85, mean age 48.6 ± 10.6 years, all male) completed a self-report survey on their playing career, number of concussions, and continuing symptoms. Participants completed somatosensory vibrotactile tasks assessing reaction time, amplitude discrimination (sequential, simultaneous), and temporal discrimination (temporal order judgment, duration discrimination). Participants were divided between those reporting persistent symptoms (“symptomatic”, n=63) and those without concerns (“non-symptomatic”, n=22).
Results
“Symptomatic” participants scored higher symptom scores compared to the “nonsymptomatic” group (P<0.001). No differences were found between groups for age (P=0.152), number of concussions (P=0.193), total years played (P=0.385), or professional career length (P=0.711). “Symptomatic” group reaction times were slower to the “nonsymptomatic” group (P<0.001). Reaction time variability were greater in the “symptomatic” group (P=0.002). Differences between groups were found for amplitude discrimination (sequential: P=0.031; simultaneous: P=0.036) and temporal order judgment (P=0.032). Significant correlations were found between total symptom scores and all somatosensory tasks. Correlations showed associations between total exposure years with temporal order judgement and reaction time.
Conclusions.
This novel study showed altered sensorimotor perception in retired athletes with persistent symptoms. Our data adds to the growing pathophysiological evidence in those who experience repetitive neurotrauma during their playing careers.
Repetitive head impact exposure, from contact and collision sports, are increasingly being attributed to increased risk of neurodegenerative disease in aging athletes. This exploratory study investigated the association of playing career in retired professional contact sport athletes with cortical neurophysiology via transcranial magnetic stimulation (TMS).
Methods
Male athletes between the ages of 28-68 years (n=113; mean age [SD] 48.8 [9.7]) who had been retired from professional sport for a minimum of five years were recruited. Cortical excitability was measured using single pulse TMS for motor evoked potentials and paired pulse transcranial magnetic stimulation short-interval intracortical inhibition and long-interval intracortical inhibition. Associations were assessed between transcranial magnetic stimulation measures and concussion history, clinical symptom scores, total career length (including junior to complete retirement), and professional career length (elite competition only).
Results
Correlations showed significant associations between motor evoked potentials and clinical symptom reporting (rho: -0.21 – -0.38; P<0.01); and motor evoked potentials and short-interval intracortical inhibition with total career length (rho: 0.26 – -0.33; P<0.01). No significant correlations were observed between single and paired-pulse transcranial magnetic stimulation and professional career length (rho: 0.16 – -0.15), nor the number of concussions (rho: 0.17 – -0.17).
Conclusions
This study is the first to report pathophysiological outcomes in a cohort of retired professional athletes associated with total career exposure, rather than professional career exposure or concussion history. TMS assessment could be considered a viable biomarker in future studies of retired athletes suspected with traumatic encephalopathy syndrome.
magnetic stimulation (TMS) for active motor threshold (aMT), motor evoked potential and cortical silent period duration (expressed as MEP:cSP ratio), and short- and long-interval intracortical inhibition (SICI and LICI). Motor threshold, MEP:cSP, SICI and LICI for both groups were correlated across age. Controls showed significant moderate correlations for MEP:cSP ratios at 130% (rho=0.48, p<0.001), 150% (rho=0.49, p<0.001) and 170% aMT (rho=0.42; p<0.001) and significant small negative correlation for SICI (rho=-0.27; p=0.030), and moderate negative correlation for LICI (rho=-0.43; p<0.001). Group-wise correlation analysis comparisons showed significant correlation differences between groups for 130% (p=0.016) and 150% aMT (p=0.009), specifically showing retired athletes were displaying increased corticomotor inhibition. while previous studies have focussed studies on older athletes (>50 years), this study is the first to characterize corticomotor differences between retired athletes and controls across the lifespan. These results, demonstrating pathophysiological differences in retired athletes across the lifespan, provide a foundation to utilise evoked potentials as a prodromal marker in supplementing neurological assessment for traumatic encephalopathy syndrome associated with contact/collision sport athletes that is currently lacking physiological biomarkers.
deactivated Bacillus subtilis (BG01-4™) high in branched-chain fatty acids (BCFA) to treat self-reported FGID. Methods: Participants (n = 67) completed a four-week intervention of BG01-4™ (n = 34) or placebo (n = 33). The Gastrointestinal Symptom Rating Scale (GSRS) served as the outcome measure, collected prior to, at two weeks, and at four weeks after completion of the intervention. Results: At four weeks, one of three primary outcomes, constipation in the experimental group, was improved by 33% compared to placebo (15%); both other primary outcomes, Total GSRS and diarrhoea, were
significantly improved in both the experimental and placebo groups (32%/26% and 20%/22%, respectively). The pre-planned secondary outcome, indigestion, was improved at four weeks (32%) but compared to the placebo (21%) was not significant (p = 0.079). Exploratory analysis, however,
revealed that clusters for constipation (18% improvement, p < 0.001), indigestion (11% improvement, p = 0.04), and dyspepsia (10% improvement, p = 0.04) were significantly improved in the intervention group compared to the placebo. Conclusions: These initial findings suggest that in people with
self-reported FGID, BG01-4™improves specific symptoms of constipation and related GI dysfunction. Longer-term confirmatory studies for this intervention are warranted. Trial registration: This study was registered prospectively (25 October 2021) at the Australian New Zealand Clinical Trials Registry
(ACTRN12621001441808p).
post-mTBI. This systematic literature review aimed to consolidate evidence for nutrition and dietaryrelated
interventions in humans with chronic mTBI. The review was registered with the International Prospective Register of Systematic Reviews (PROSPERO; CRD42021277780) and conducted following the Preferred Reporting for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Three
reviewers searched five databases (PubMed/MEDLINE, Web of Science, SPORTDiscus, CINAHL Complete and Cochrane), which yielded 6164 studies. Nine studies met the inclusion criteria. The
main finding was the lack of interventions conducted to date, and a quality assessment of the included studies was found to be fair to good. Due to heterogeneity, a meta-analysis was not feasible. The six nutrition areas identified (omega-3 fatty acids, melatonin, Enzogenol®, MLC901, ketogenic diet and
phytocannabinoids) were safe and well-tolerated. It was found that these nutritional interventions may improve cognitive failures, sleep disturbances, anxiety, physical disability, systolic blood pressure volume and sport concussion assessment tool scores following mTBI. Potential areas of improvement
identified for future studies included blinding, reporting compliance, and controlling for confounders.
In conclusion, further research of higher quality is needed to investigate the role of nutrition in recovery from mTBI to reduce the burden of chronic outcomes following mTBI.
significance may be underestimated. Acute or subacute measurement of non-concussive injury is challenging as the pathological response and injury is poorly described. There is therefore a need for a greater understanding of the pathological consequences of exposure. Growing evidence indicates that resting-state functional connectivity (rs-fMRI) changes in the Default Mode Network (DMN) may be an important biomarker that is sensitive to characterize these impacts. In this work, we examined functional connectivity changes within the DMN of ARF players to evaluate its potential as an early biomarker for non-concussive impacts. Based on rs-fMRI, we compare the DMN of 47 sub-elite ARF players (mean
age 21.5±2.7 years [SD], males 57%) and 42 age-matched healthy controls (mean age 23.2±2.3 years [SD], males 48%) using Independent Component Analysis (ICA) and Dual Regression. This approach permits an unbiased decomposition of brain activity into networks with principled handling of statistical error. An 83% increase in DMN connectivity (as measured by the Strictly Standardized Mean Difference on values derived from Dual Regression) was observed in ARF players in the left retrosplenial cingulate cortex compared to healthy controls (FDR-corrected p-value from dual regression = 0.03, 95% CI computed via bootstrapping was 58% to 116%). The AUC for distinguishing ARF players from controls was 0.80 (95% CI; [0.71, 0.89]), equating to a PPV of 78% and a NPV of 74%. These results are preliminary; future work could investigate robustness to different random initializations of ICA and validate the findings on an independent testing set, as well as investigate longitudinal changes in ARF players over the course of a playing season.
Interest continues investigating pathophysiology of athlete cohorts with a history involving cumulative career exposure of repeated concussion and non-concussion impacts. One area yet to be explored involves the somatosensory system. Using a novel sensorimotor technique, this study measured the somatosensory system in retired contact sport athletes exposed to repetitive neurotrauma.
Materials and Methods
Retired athletes (n=85, mean age 48.6 ± 10.6 years, all male) completed a self-report survey on their playing career, number of concussions, and continuing symptoms. Participants completed somatosensory vibrotactile tasks assessing reaction time, amplitude discrimination (sequential, simultaneous), and temporal discrimination (temporal order judgment, duration discrimination). Participants were divided between those reporting persistent symptoms (“symptomatic”, n=63) and those without concerns (“non-symptomatic”, n=22).
Results
“Symptomatic” participants scored higher symptom scores compared to the “nonsymptomatic” group (P<0.001). No differences were found between groups for age (P=0.152), number of concussions (P=0.193), total years played (P=0.385), or professional career length (P=0.711). “Symptomatic” group reaction times were slower to the “nonsymptomatic” group (P<0.001). Reaction time variability were greater in the “symptomatic” group (P=0.002). Differences between groups were found for amplitude discrimination (sequential: P=0.031; simultaneous: P=0.036) and temporal order judgment (P=0.032). Significant correlations were found between total symptom scores and all somatosensory tasks. Correlations showed associations between total exposure years with temporal order judgement and reaction time.
Conclusions.
This novel study showed altered sensorimotor perception in retired athletes with persistent symptoms. Our data adds to the growing pathophysiological evidence in those who experience repetitive neurotrauma during their playing careers.
Repetitive head impact exposure, from contact and collision sports, are increasingly being attributed to increased risk of neurodegenerative disease in aging athletes. This exploratory study investigated the association of playing career in retired professional contact sport athletes with cortical neurophysiology via transcranial magnetic stimulation (TMS).
Methods
Male athletes between the ages of 28-68 years (n=113; mean age [SD] 48.8 [9.7]) who had been retired from professional sport for a minimum of five years were recruited. Cortical excitability was measured using single pulse TMS for motor evoked potentials and paired pulse transcranial magnetic stimulation short-interval intracortical inhibition and long-interval intracortical inhibition. Associations were assessed between transcranial magnetic stimulation measures and concussion history, clinical symptom scores, total career length (including junior to complete retirement), and professional career length (elite competition only).
Results
Correlations showed significant associations between motor evoked potentials and clinical symptom reporting (rho: -0.21 – -0.38; P<0.01); and motor evoked potentials and short-interval intracortical inhibition with total career length (rho: 0.26 – -0.33; P<0.01). No significant correlations were observed between single and paired-pulse transcranial magnetic stimulation and professional career length (rho: 0.16 – -0.15), nor the number of concussions (rho: 0.17 – -0.17).
Conclusions
This study is the first to report pathophysiological outcomes in a cohort of retired professional athletes associated with total career exposure, rather than professional career exposure or concussion history. TMS assessment could be considered a viable biomarker in future studies of retired athletes suspected with traumatic encephalopathy syndrome.
magnetic stimulation (TMS) for active motor threshold (aMT), motor evoked potential and cortical silent period duration (expressed as MEP:cSP ratio), and short- and long-interval intracortical inhibition (SICI and LICI). Motor threshold, MEP:cSP, SICI and LICI for both groups were correlated across age. Controls showed significant moderate correlations for MEP:cSP ratios at 130% (rho=0.48, p<0.001), 150% (rho=0.49, p<0.001) and 170% aMT (rho=0.42; p<0.001) and significant small negative correlation for SICI (rho=-0.27; p=0.030), and moderate negative correlation for LICI (rho=-0.43; p<0.001). Group-wise correlation analysis comparisons showed significant correlation differences between groups for 130% (p=0.016) and 150% aMT (p=0.009), specifically showing retired athletes were displaying increased corticomotor inhibition. while previous studies have focussed studies on older athletes (>50 years), this study is the first to characterize corticomotor differences between retired athletes and controls across the lifespan. These results, demonstrating pathophysiological differences in retired athletes across the lifespan, provide a foundation to utilise evoked potentials as a prodromal marker in supplementing neurological assessment for traumatic encephalopathy syndrome associated with contact/collision sport athletes that is currently lacking physiological biomarkers.
deactivated Bacillus subtilis (BG01-4™) high in branched-chain fatty acids (BCFA) to treat self-reported FGID. Methods: Participants (n = 67) completed a four-week intervention of BG01-4™ (n = 34) or placebo (n = 33). The Gastrointestinal Symptom Rating Scale (GSRS) served as the outcome measure, collected prior to, at two weeks, and at four weeks after completion of the intervention. Results: At four weeks, one of three primary outcomes, constipation in the experimental group, was improved by 33% compared to placebo (15%); both other primary outcomes, Total GSRS and diarrhoea, were
significantly improved in both the experimental and placebo groups (32%/26% and 20%/22%, respectively). The pre-planned secondary outcome, indigestion, was improved at four weeks (32%) but compared to the placebo (21%) was not significant (p = 0.079). Exploratory analysis, however,
revealed that clusters for constipation (18% improvement, p < 0.001), indigestion (11% improvement, p = 0.04), and dyspepsia (10% improvement, p = 0.04) were significantly improved in the intervention group compared to the placebo. Conclusions: These initial findings suggest that in people with
self-reported FGID, BG01-4™improves specific symptoms of constipation and related GI dysfunction. Longer-term confirmatory studies for this intervention are warranted. Trial registration: This study was registered prospectively (25 October 2021) at the Australian New Zealand Clinical Trials Registry
(ACTRN12621001441808p).
post-mTBI. This systematic literature review aimed to consolidate evidence for nutrition and dietaryrelated
interventions in humans with chronic mTBI. The review was registered with the International Prospective Register of Systematic Reviews (PROSPERO; CRD42021277780) and conducted following the Preferred Reporting for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Three
reviewers searched five databases (PubMed/MEDLINE, Web of Science, SPORTDiscus, CINAHL Complete and Cochrane), which yielded 6164 studies. Nine studies met the inclusion criteria. The
main finding was the lack of interventions conducted to date, and a quality assessment of the included studies was found to be fair to good. Due to heterogeneity, a meta-analysis was not feasible. The six nutrition areas identified (omega-3 fatty acids, melatonin, Enzogenol®, MLC901, ketogenic diet and
phytocannabinoids) were safe and well-tolerated. It was found that these nutritional interventions may improve cognitive failures, sleep disturbances, anxiety, physical disability, systolic blood pressure volume and sport concussion assessment tool scores following mTBI. Potential areas of improvement
identified for future studies included blinding, reporting compliance, and controlling for confounders.
In conclusion, further research of higher quality is needed to investigate the role of nutrition in recovery from mTBI to reduce the burden of chronic outcomes following mTBI.