The issue of effortful patient performance has been an area of clinical interest in individuals with minor traumatic brain injury (mTBI). Clinical attention to this area has increased largely because of an increase in the number of worker's compensation claims, injury-related lawsuits and/or insanity defense pleas. As patients are presented with the opportunity for secondary gain, the issue of optimum performance on neuropsychological measures becomes salient. In addition to neurocognitive deficits, there are psychological characteristics associated with mTBI including depression, emotional disturbance, personality changes, and other psychopathology. This study utilized the MSVT, a set of standard neuropsychological instruments, and the Minnesota Multiphasic Inventory-2 (MMPI-2) to investigate the relationships between effort, psychological characteristics, and neuropsychological functioning in individuals with minor traumatic brain injuries. The first objective of this study was to determine which psychological factors were related to effort in mTBI. The second objective was to determine if there were differences between groups that performed poorly on effort testing and groups that performed adequately on effort testing, based on relevant psychological characteristics. The results of the analyses supported the first hypothesis. Hysteria was inversely related to effort, and Mania was positively related to effort on one of five measures of effort. The second hypothesis was not supported.

The majority of clinical impairments following a concussion resolve within 7-10 days. However, there is limited clarity as to long-term impact of this injury on neurocognitive function, motor control, and particularly integration of these domains. While repetitive head trauma is associated with numerous neurological disorders, the link is not well described. Visual-motor tracking tasks have been used to identify differences in visual processing, error detection, and fine motor control in aging and numerous pathologies. Examining the complexity of motor output from visual-motor tracking provides insight into multiple cognitive and motor function domains, and into fine motor control used for daily living, work, and sport. The purpose of this dissertation was, therefore, to: (1) use multiple regression to determine the extent to which concussion history and symptoms (loss of consciousness and amnesia) influence visual-motor task performance multiscale complexity, and (2) determine whether task performance complexity can distinguish, through logistic regression and prediction, between individuals with and without a history of concussion. In study 1, individuals with (n = 35) and without (n = 15) a history of concussion performed a visual-motor tracking task. Men and women exhibited linear decreases in task performance complexity, as well as midand high-frequency task performance components, with increasing numbers of concussions. However, men and women exhibited differing patterns, as did those with and without a history of concussion-related loss of consciousness. Finally, trial-to-trial complexity variability increased with increasing numbers of concussions. Findings indicate (1) a cumulative reduction in the way in which previously concussed individuals process and integrate visual information to guide behavior and (2) gender is an important consideration in concussion-related visual-motor outcomes. In Study 2, individuals with (n = 85) and without (n = 42) a history of concussion performed a visualmotor tracking task. Linear and nonlinear measures of task performance were used to build gender-specific logistic classification models using 10-fold cross-validation. When ensuring 80% sensitivity, the best models were 75-80% accurate in predicting a history of concussion. Such discrimination has clinical value in identifying individuals who merit further evaluation and observation over time for conditions related to repetitive head traumas.

No description available.

An examination of neck strength, and other possible predictors of concussion risk in university athletes and how these variables relate to concussion recovery in this cohort. / Concussion incidence in university athletes has been increased drastically over the last two decades. Prevention of concussion injuries is still elusive and scarcely reported in the literature. Certain athletes are at greater risk for concussion than others. Identifying these risk factors is an important first step in identifying those who are at highest risk for concussion. Concussions are biomechanical injuries therefore addressing the strength of the neck musculature might be a significant modifiable risk factor in concussion prevention. Greater neck strength may help to attenuate the forces that cause concussion and either prevent injury or decrease the severity. There are some known risk factors for concussion, including age and female sex, however this does not account for all of the variability in concussion incidence in university athletes. Further exploration into the importance of neck strength and concussion in university athletes is required to identify alternative prevention strategies available to athletes. The purpose of this research was to examine if neck strength and anthropometric variables are significant predictors of concussion risk and concussion recovery time in Canadian university athletes. Chapter One provides a review of the current literature on concussion. It presents the background information for concussion risk, etiology, assessment, and management in university athletes. This chapter also reviews the literature to date on neck strength in concussion and assessments of neck strength in athletes. Chapter Two presents a study evaluating the risk of concussion in a group of Canadian university varsity athletes (n = 246). Neck strength and anthropometric variables are assessed for their significance in predicting concussion risk in this cohort along with published covariates. Neck pain and past concussion history were found to be the most significant predictors of concussion in this population. Chapter Three provides an exploration into the importance of neck strength and anthropometric variables in length of recovery in concussed athletes (n = 35). The Sport Concussion Assessment Tool, 3rd edition was used to evaluate symptom intensity in these athletes. A multiple linear regression model was used to predict recovery time. Symptom score and neck pain were the only significant predictors of concussion recovery time in varsity athletes. Chapter Four presents the implications of the two aforementioned studies for clinical practice, future research, and policy recommendations. More in-depth assessments prior to the beginning of competition should be considered in identifying athletes who are at greatest risk for concussion. Athletes with significant past concussion history should be evaluated more closely and informed of their heightened risk for subsequent injury. / Thesis / Master of Health Sciences (MSc)

Bakgrund: Inom både dam- och herrishockey är hjärnskakningar vanligt förekommande. Definitionen av hjärnskakning är att hjärnan hamnar i rörelse av direkt eller indirekt våld mot huvudet. Riktlinjer finns framtagna över hur hjärnskakningar ska hanteras och rehabiliteras och bör tas på allvar då det finns risk för blödning eller kvarstående symtom. SCAT-3 är ett värderingsverktyg vid hjärnskakningar, där ingår en symtomskattning. En hög poängsumma innebär stora symtomatiska besvär. Inga studier har påträffats över förekomst av hjärnskakningar samt hjärnskakningslikande symtom för spelare i Svenska damhockeyligan (SDHL).Syfte: Att beskriva förekomst av hjärnskakningar samt hjärnskakningsliknade symtom hos ishockeyspelare i SDHL jämfört med en kontrollgrupp.Metod: Kvantitativ, deskriptiv samt komparativ tvärsnittsdesign. Ett internetbaserat testformulär byggt på SCAT-3. Totalt 92 deltagare, n=48 hockeyspelare, n=44 kontrollgrupp.Resultat: Förekomsten av hjärnskakningar var 64,6 % bland ishockeyspelare, och signifikant högre jämfört med kontrollgruppen 38,6 % (p=0,013). Totalsumma av hjärnskakningsliknande symtom bland hockeyspelarna (17,6 poäng) jämfört med kontrollgruppen (16,4 poäng) skiljde sig inte signifikant. Vanligaste symtomen bland hockeyspelarna var känsla av trötthet/brist på energi, nackont samt irritation. Vanligaste symtomen för kontrollgruppen var känsla av trötthet/brist på energi, mer känslosam än vanligt och koncentrationssvårigheter. Konklusion: 64,6 % av spelarna i SDHL har fått minst en hjärnskakning. Hjärnskakningar var vanligare bland spelare i SDHL än i kontrollgruppen. Ingen signifikant skillnad av hjärnskakningsliknade symtom sågs mellan grupperna. Symtomen var inte tillräckligt specifika för att jämföra grupper emellan, utan bör enbart jämföras individuellt. / Background: Concussions are frequently occurring in ice hockey, both women and men hockey. A concussion appears from direct or indirect violence against the head, that will cause brain movement, and in worse case a bleeding on the brain. There are guidelines for concussion management and rehabilitation that needs to take seriously as there are risks of retaining symptoms. SCAT-3 is a concussion tool, with a symptom scale. A higher score means bigger issues of the symptoms. No studies have been done on the concussion frequency and concussion-similar symptoms for players in the Svenska damhockeyligan (SDHL).Purpose: Find out frequency of concussion and concussion-similar symptoms compared to a control group. Method: Quantitative descriptive and comparative cross-sectional design. An internet based test, based on SCAT-3, with total 92 participants, n=48 hockey players, n=44 control group.Results: Concussion frequency was 64.6 % for hockey players, and significant higher compared to the control group 38.6% (p=0.013). In total, concussion-similar symptom score for hockey players was 17.6 points and for control group 16.4 points. No significant difference between the groups. The most common symptoms among hockey players were fatigue or low energy, neck pain and irritation. In the control group, fatigue or low energy, more emotional and concentration difficulties was the most common.Conclusion: 64.6 % of the players in SDHL had received at least one concussion. Concussions are more common among players in SDHL than a control group. No significant difference of concussion-similar symptoms. The symptoms are not specific

Background and aims: The provenance of post-concussion symptoms (PCS) and post-traumatic stress (PTSD) after mild traumatic brain injury (mTBI) is controversial. This thesis investigated factors influencing these two conditions separately, as well as the interplay between PCS and PTSD, in individuals with mTBI and a control sample without mTBI (orthopaedic injuries). Method: Consecutive adult attendees of an Emergency Department with mTBI or orthopaedic injury were prospectively recruited and completed the Rivermead Post-concussion Questionnaire (RPQ) and Trauma Screening Questionnaire (TSQ) for PTSD at two weeks (T1) and three months (T2) post-injury. The sample at T1 consisted of 34 with complicated mTBI, 76 with uncomplicated mTBI and 47 with orthopaedic injury, and 18 with complicated mTBI, 43 with uncomplicated mTBI and 33 orthopaedic controls at T2. Results: Although there were no differences in overall PCS symptomology between groups, a subset of PCS symptoms (headaches, dizziness and nausea) was found to be specific to mTBI at both time points. These symptoms are proposed to have a neurological basis, as opposed to a psychological basis. PTSD interacted with PCS, particularly in mTBI, such that PTSD was associated with greater “neurogenic” and “psychogenic” symptomology in this group, but only a moderate increase in psychogenic symptoms for controls. A model of the influence of PTSD on PCS is presented. PTSD was influenced by poor memory quality for the traumatic event and attribution of blame to others, but not by mTBI. Discussion and conclusions: Though mTBI may set the scene for at least neurogenic symptoms of PCS to occur, psychological mechanisms, particularly PTSD, have a significant role in the persistence of PCS. Our findings suggest the need for a clear story and sense of meaning for a traumatic event for good recovery from PTSD. Taken together, the results suggest that psychological interventions, particularly aimed at PTSD, may be most effective after mTBI.

Athletes competing in the unarmed combat sport of mixed martial arts (MMA) are at an increased risk for long-term neurological consequences due to repetitive head trauma. Mass differentials as well as reported differences in fight styles between Lightweight and Heavyweight fighters in MMA may affect head impact kinematics creating different levels of head injury risk. Factors that influence the risk for head injury include the frequency, magnitude and interval of head impacts. The purpose of this study was to compare differences in frequency, frequency distribution of impact magnitudes, and time interval between head impacts per match between Lightweight and Heavyweight fighters in the Ultimate Fighting Championship (UFC). Head impacts of 60 fighters were documented from 15 Lightweight and 15 Heavyweight MMA fight videos. Impact type, frequency, and interval were recorded for each fighter, followed by the reconstruction of 345 exemplar impacts in the laboratory using a Hybrid III headform and finite element modeling to determine impact magnitudes. Next, head impacts (punches, kicks, knees and elbows) from fight videos were visually estimated to determine their corresponding magnitude range and establish the frequency distribution of impact magnitudes. The study revealed no significant differences in overall impact frequency and interval between Lightweight and Heavyweight fighters. The frequency distribution of different impact magnitudes was significantly different, with Lightweights sustaining significantly more Very Low, and High magnitude impacts. Overall, both Lightweight and Heavyweight MMA fighters sustain similar impact characteristics as other high-risk athletes including professional boxers and football players. Understanding the different factors that create brain trauma allows for the monitoring, identification, and protection of higher-risk athletes within these two weight classes.

A wearable system that can be used in different settings to collect gait parameters on subjects with a mild traumatic brain injury (mTBI) would allow clinicians to collect needed data of subjects outside of the laboratory setting. Mild traumatic brain injuries stem from a number of causes such as illnesses, strokes, accidents or battlefield traumas. These injuries can cause issues with everyday tasks, such as gait, and are linked with vestibular dysfunction [1]. Different wearable sensor systems were analyzed prior to starting this study along with relevant gait parameters associated with mild traumatic brain injury. To monitor gait parameters relevant to mild traumatic brain injury (cadence, torso rate of rotation, head rate of rotation and stride length) a wearable sensor system was selected (APDM Opal Movement Monitor [13]) and compared against the gold standard optical tracking system (Vicon) [2]. A group of ten, 20-27 year old, healthy subjects were used to validate the APDM Movement Monitor system using the Pearson's R correlation value [35]. Subjects were asked to wear the APDM movement monitors in conjunction with the reflective markers of the Vicon system while performing three sessions of gait trials: a normal gait speed, a fast gait speed and a slow gait speed. Using the Pearson's R correlation values, cadence, torso rate of rotation, and head rate of rotation were found to be highly correlated between both systems. The Pearson's R correlations for cadence, torso rate of rotation, head rate of rotation and stride length were 0.967, 0.907, 0.942, and 0.861, respectively. These correlation values suggest the gait parameters relevant to mild traumatic brain injury are highly correlated between both the APDM Movement Monitor system and the Vicon system, and APDM's wearable sensor system was lightweight, portable and less costly than the Vicon system.

Mild Traumatic Brain Injury (mTBI), often called concussion, has become a growing public health concern, prevalent in both athletic and military settings. In response, many researchers have explored cognitive outcomes post-mTBI, with a plethora of meta-analyses summarizing these findings; however, these meta-analyses examine solely mean performances on cognitive tasks, ignoring intra-individual variability (IIV) in cognitive performance that may elucidate neuropsychological impairment following mTBI. The current thesis involved two studies, responding to both the growing meta-analytic research and limited IIV findings. Study 1: Many meta-analyses have amalgamated individual study results on post-mTBI neuropsychological outcomes. With the abundance of meta-analyses, a systematic review of meta-analyses stands as the next logical step. Method: A systematic literature search yielded 11 meta-analyses meeting inclusion criteria (i.e., English-language systematic reviews/meta-analyses covering post-mTBI observational cognitive research on late adolescents/adults), with their findings qualitatively synthesized based on moderator variables (i.e., cognitive domain, time since injury, past head injury, participant characteristics, comparison group, assessment technique, and persistent symptoms). Results: The overall effect sizes ranged for both general (range: .07-.61) and sports-related mTBI (range: .40-.81) and differed both between and within cognitive domains, with executive functions appearing most sensitive to multiple mTBI. Cognitive domains varied in recovery rates, but overall recovery occurred by 90 days post-injury for most individuals and by seven days post-injury for athletes. Greater age/education and male gender produced smaller effects sizes, while high school athletes suffered the largest deficits post-mTBI. Control-group comparisons yielded larger effects than within-person designs, while assessment techniques had limited moderating effects. Conclusions: Overall, meta-analytic review quality remained low with few studies assessing publication or study quality bias. Meta-analyses consistently identified adverse acute mTBI-related effects and fairly rapid symptom resolution. Study 2: The long-term outcomes of executive functions and IIV following mTBI are unclear due to inconsistent and limited research, respectively. Further, the relationship between physical activity (PA) and cognitive performance at young adulthood remains almost fully unexplored. In turn, the current study aimed to (a) assess the diagnostic utility of both executive functions and IIV at predicting mTBI history and (b) evaluate the interaction between PA levels and mTBI on both of these cognitive metrics. Method: Altogether 138 self-identified athletes (Mage = 19.9 ± 1.91 years, 60.8% female, 19.6% 1 mTBI, 18.1% 2+ mTBIs) completed three executive-related cognitive tasks (i.e., N-Back, Go/No-go, Local-Global). Ordinal logistic regression analyses examined the joint effect of person-mean and IIV as predictors of mTBI status. Multi-level models examined mTBI and PA levels as predictors of trial-to-trial changes in performance. Results: Only mean response time (RT) for the Local-Global task predicted mTBI status, while no IIV variables reached unique significance. PA levels predicted subtle within-task decreases in RT across Local-Global trials. Conclusions: IIV research on mTBI remains limited; however, the preliminary results do not indicate any additional predictive value of IIV indices above mean performances. For executive functions, shifting appeared most affected, with past researchers identifying post-mTBI impairment in attentional processing. Higher PA levels minutely benefited within-task shifting and mean inhibitory performance, although these finding require cautious interpretation. / Graduate / 0622 / jkarr@uvic.ca

Traumatic brain injury (TBI) effects a large number of individuals, both civilians and military personnel, every year. The neuroinflammatory response mounted in the brain following a head injury continues long after the effects of initial subside. While it was initially thought to only occur in moderate or severe TBI, the deleterious effects of this cascade have recently been identified in patients with mild TBI (mTBI). Hypopituitarism is an often underreported condition and can result from TBI of all severity. The long-term sequelae of TBI can manifest in or exacerbate many other comorbidities of brain injury, such as neuroendocrine dysfunction or mental health conditions. Both TBI and hypopituitarism can present with symptoms similar to some psychiatric disorders, or exacerbation comorbid conditions. Veteran patients presenting to their primary care providers with symptoms of irritability, depression, anxiety, or cognitive and behavioral changes may meet criteria to receive diagnoses of psychiatric illnesses prevalent in the military population, while not being evaluated for pituitary dysfunction, and thus receive inadequate treatment. The proposed study aims to identify the prevalence of patients that are receiving psychiatric treatment that have both a history of mTBI and reduced levels of pituitary hormones on serum assays. By identifying a significant portion of this population, future studies can assess the impact that hormonal replacement has on success of psychotherapy, resolution of symptoms, and impact on functional status, among other factors.