| dc.description.abstract | Rugby has one of the highest incidences of concussion among all full-contact sports. There has been a global increase in rugby participation, now estimated at over eight million people worldwide. With the introduction of professionalism in 1995, an increase in injuries at both amateur and professional level in northern hemisphere international rugby has coincided with increases in average body mass of rugby players by an estimated 25%. Hence,the modern game has larger, stronger players with greater body mass,experiencing larger impact forces, resulting in greater risk of head injury.Alongside increasing concussion incidence among professional rugby players in recent times due to greater awareness and higher rates of head injury reporting, the risks posed by repeated concussion have become a focus of scientific investigation and a major public health concern. Given the elevated risk of concussion in rugby, there is a need to investigate long‐term brain health outcomes in this population.There is emerging evidence suggesting associations between concussion and/ or head impact exposure and potential long term neurological impairments and neurodegenerative diseases.
In an effort to expand the limited evidence base in this field, the overall aim of this thesis was to explore the influence of a career of professional rugby on brain health in retirement. In pursuing this aim, two systematic reviews of the existing literature and five original studies were completed. Systematic Review I –the first review of brain health in retired professional rugby players aimed to establish the evidence regarding long-term neurocognitive functioning and mental health status of living retired rugby players. Nine studies met the inclusion criteria; the available evidence suggested some preliminary evidence for decreased cognitive functioning and a high mental health burden among retired rugby players. However, cautious interpretation of findings was needed as methodological biases reduced the overall quality of studies and limited the conclusions that could be drawn. The heterogeneity of outcome measures, participant characteristics and self-reported methods were among the noted study limitations. This review suggested that large gaps remain in the understanding of the cause-and-effect relationships between playing rugby and long-term brain health in retired players.
Given the limited studies found pertaining to retired rugby players specifically in Systematic Review I, a broader scope of the literature was undertaken in Systematic Review 2. The specific aim of the review was to appraise and synthesise the literature on the long-term cognitive health status of retired athletes. Evidence of poorer cognitive health among retired athletes with a history of concussion and head-impact exposure was found to be mixed. The results indicated that retired athletes with a history of sports-related concussion had declined cognitive performance in domains of memory, executive function and psychomotor function later in life. Retired athletes also appeared to have increased self-reported cognitive difficulties, but the paucity of high-quality, prospective studies limited the conclusions that could be drawn regarding cause-and-effect.In light of the findings from Systematic Review 1 and 2, cross-sectional Study I was conducted to investigate the validity of self-reported concussion history among professional rugby union players. Following on from this, the large cross-sectional Studies1I-V were conducted to explore (1) physical health (2) mental health (3) cognitive functioning and (4) multisensory processing among retired professional rugby players compared to retired professional rowers. Reliance on athlete self-reported concussion history is a limitation noted in the literature pertaining to long-term effects of concussion. A sample of 63 professional rugby union players were enrolled in Study I. Agreement between self-reported and clinically diagnosed concussions was found to be fair among the rugby players, with the average player under-reporting the number of clinically diagnosed concussions. Lifetime concussion history was found to be significantly negatively correlated with player self-report accuracy, with recall worsening as the number of lifetime concussions increased. However, the test re-test reliability of the Michigan TBI Identification Method was moderately strong. These findings suggest that there is a need for methodological improvements in concussion reporting and documentation among rugby players. Ninety-five retired athletes took part in Studies II-V; including 67 retired professional rugby players and 28 retired international rowers. The prevalence of overweight and obesity was found to be higher among the retired rugby players compared to the retired rowers in Study II. Indications of higher visceral and body fat and hypertension were also revealed among the rugby cohort. Significantly higher levels of pain and disability and alcohol usage was found among retried rugby players compared to rowers.Lower levels of exercise was found to be associated with greater levels of pain and disability, indicating that past participation in professional rugby may result in greater levels of pain and functional limitations in retirement. Results from this study highlight modifiable factors such as overweight and obesity and hypertension in retired professional rugby players which are associated with long-term risk of negative health outcomes.
Study III found that the point prevalence of depression among rugby players was 28%, which was higher than the rowers and the general population. The rugby group were found to have a significantly greater sense of athletic identity when compared to the rowers. Concussion history estimates were not associated with mental health indicators. However, multiple regression analysis revealed decreased satisfaction with life, decreased resilience, greater athletic identity and higher levels of pain and disability were significant predictors of depression among the rugby cohort. These factors were found to account for 67% of the variation in the chance of former rugby players having depression. Results demonstrated that the prevalence of mental health symptoms among former rugby players was 10% higher for alcohol misuse, 17% higher for depression, 13% higher for pain and disability and 20% higher for sleep disturbance compared to rowers.This study provides an insight into the estimate of mental health burden among retired professional rugby players. A combination of factors, including those which are unique to the elite athlete, alongside common stressors which affect the general population, make former professional rugby players an at-risk demographic for experiencing mental health issues.Interventions and strategies to prepare players for career transition may help to mitigate the risk of the occurrence of mental health symptoms and disorders in retirement. The association between the pain disability index and depression indicators suggests that interdisciplinary medical care and support for rugby players should be incorporated into the overall management of the transitioning player.Timely mental health diagnoses and management strategies, which are specific to this rugby population, are required.
In Study IV, the retired rugby players showed no reduction in performance on the CANTAB tests of neurocognitive functioning compared to retired rowers.Cluster-based analysis revealed no association between concussion history estimates and performance on CANTAB tests.Relative to rowers, rugby players performed significantly better in the domains and subdomains of attention and psychomotor speed and working memory assessed by the CANTAB, which revealed that the rugby players performed significantly better on tests of reaction time,motor speed, processing speed and visuospatial memory.Rugby players also performed significantly better than the general population on the same tasks based on normative data. Findings in the CANTAB tests of neurocognitive functioning revealed no overt negative impact of a concussion or years of exposure to rugby on performance. The fifth and final study of this thesis was conceptualised in response to the findings of the systematic reviews and the need for subtle tests in relation to concussion markers. The insights gained were integrated into completing, for the first time, a novel assessment of multisensory integration among retired professional rugby players using a robust audio-visual illusion paradigm-the ‘Sound Induced Flash Illusion Task’. This task provided a means of assessing multisensory‐integration,which may correlate with underlying concussive pathology and functional and structural cerebral disturbances. Compromised audio–visual integration or increased susceptibility to the sound induced flash illusion was found among former rugby players compared to the rowers. Concussion history estimates significantly predicted the odds of an accurate response suggesting that history of concussion may have a deleterious effect on multisensory integration efficiency. Visual illusions induced by sound may represent a valuable tool to explore the effects of concussion on aging rugby players. However, associations between susceptibility to the sound induced flash illusion and implications of repetitive sports related concussion need to be further investigated using large-scale comparisons.The current thesis employed comparisons across multiple measures and empirically validated measures of brain health and provides an insight intocognitive-perceptual measures and their applicability to future exploration of cognitive health and multisensory processing within retired professional rugby player cohorts.Healthy brain aging is known to be influenced by multiple factors both inert and environmental. The overall benefits of physical activity associated with sports participation are well established. However,in order to gain continued and optimal brain health benefits from exercise, it should be continued throughout the lifespan. Negative health-related factors and behaviours in retirement identified among rugby players in the current study, including; excessive alcohol usage, physical inactivity, sleep disturbance and pain and disability are known to adversely affect mental and cognitive health and increase the risk of neurodegeneration. Rugby players are a unique cohort of individuals. The results from the current study suggest that transition from professional rugby may present difficulties for players, particularly due to issues surrounding identity, pain and satisfaction with post professional rugby life.The transitional implications of retiring from professional rugby on brain health need to be explored further. A transitioning program from professional rugby for example could help protect players from the potential adverse consequences of abrupt physical, social and lifestyle changes associated with retirement.A proactive approach to management and education with regard to long-term physical health, particularly musculoskeletal morbidity, within professional rugby is required. Issues such as pain and disability associated with the physicality of professional rugby need to be addressed. The game of rugby is becoming more physical and players are required to have a larger body mass. Therefore, body composition changes which occur in retirement should be viewed in the context of known cardiovascular risk profiles among the general population.The current cross-sectional exploratory research provides information regarding cognitive performance of retired elite rugby players in the early stages of retirement from competition across multiple neurocognitive and perceptual domains. However, long-term follow-up would be required to delineate any negative impacts of concussion in this cohort as they age. Cognitive reserve and resilience owing to the young age of players may have influenced the current results. | en |
