Sarah Mc Fie

Risk factors for sports concussion: an evidence-based systematic review

Concussion is a common sports injury with approximately 1.6–3.8 million sport-related concussions reported in the USA annually. Identifying risk factors may help in preventing these injuries. This systematic review aims to identify such risk factors. Three electronic databases; ScienceDirect, PubMed and SpringerLink, were searched using the keywords ‘RISK FACTORS’ or ‘PREDISPOSITION’ in conjunction with ‘SPORT’ and ‘CONCUSSION’. Based on the inclusion and exclusion criteria, 13 628 identified titles were independently analysed by two of the authors to a final list of 86 articles. Only articles with a level of evidence of I, II and III were included according to robust study design and data analysis. The level of certainty for each risk factor was determined. A high level of certainty for increased risk of a subsequent concussion in athletes sustaining more than one previous concussion was reported in 10 of 13 studies. Further, a high level of certainty was assigned to match play with all 29 studies reporting an increased concussion risk during matches. All other risk factors were evaluated as having a low level of certainty. Although several risk factors were identified from the appraised studies, prospective cohort studies, larger sample sizes, consistent and robust measures of risk should be employed in future research.

Contact technique and concussions in the South African under-18 Coca-Cola Craven Week Rugby tournament

Abstract In rugby union, understanding the techniques and events leading to concussions is important because of the nature of the injury and the severity and potential long-term consequences, particularly in junior players. Proper contact technique is a prerequisite for successful participation in rugby and is a major factor associated with injury. However, the execution of proper contact technique and its relationship to injury has yet to be studied in matches. Therefore, the aim of this study was to compare contact techniques leading to concussion with a representative sample of similarly matched non-injury (NI) contact events. Injury surveillance was conducted at the 2011–2013 under-18 Craven Week Rugby tournaments. Video footage of 10 concussive events (5 tackle, 4 ruck and 1 aerial collision) and 83 NI events were identified (19 tackle, 61 ruck and 3 aerial collisions). Thereafter, each phase of play was analysed using standardised technical proficiency criteria. Overall score for ruck proficiency in concussive events was 5.67 (out of a total of 15) vs. 6.98 for NI events (n = 54) (effect size = 0.52, small). Overall average score for tackler proficiency was 7.25 (n = 4) and 6.67 (n = 15) for injury and NI tackles, respectively (out of 16) (effect size = 0.19, trivial). This is the first study to compare concussion injury contact technique to a player-matched sample of NI contact techniques. Certain individual technical criteria had an effect towards an NI outcome, and others had an effect towards a concussive event, highlighting that failure to execute certain techniques may substantially increase the opportunity for concussion.

Clozapine decreases exploratory activity and increases anxiety-like behaviour in the Wistar-Kyoto rat but not the spontaneously hypertensive rat model of attention-deficit/hyperactivity disorder.

The spontaneously hypertensive rat (SHR) is the most widely used animal model of ADHD. SHR has been found to have increased glutamate-stimulated noradrenaline release from varicosities in several brain areas. Besides its effects on dopamine D4 receptors, clozapine, an atypical antipsychotic with antagonistic effects on α(1)-adrenoceptors, may reduce activation of α(1)-adrenoceptors in SHR and thereby attenuate their hyperactivity. The aims of the study were to determine the effect of clozapine (post-natal day (P) 21-P35, 10 mg/kg/day) on SHR and Wistar-Kyoto (WKY), SHRs normotensive control, and a standard laboratory strain, Sprague Dawley (SD). Rat behaviour was assessed in the open field (P32), novel object (P33) and elevated plus maze (P34) tests that measured locomotor and anxiety-related behaviour. An in vitro superfusion technique was used to measure [(3)H]noradrenaline release in prefrontal cortex (PFC) and hippocampal slices (P35 or P36). Clozapine decreased exploratory activity in WKY, consistent with antagonism of dopamine D4 and α(1)-adrenoceptors reducing the behavioural response to novelty. Clozapine also increased anxiety-related behaviour of WKY. However, clozapine did not affect SHR, suggesting that genetic predisposition may play a role in determining clozapines behavioural effects. WKY have been shown to have higher levels of dopamine D4 receptor expression in the PFC than SHR, which may be a reason for their elevated response to clozapine. SHR released more [(3)H]noradrenaline from PFC and hippocampal slices in response to glutamate- and elevated potassium-stimulation, compared to WKY and SD rats. However clozapine treatment did not affect glutamate-, GABA- or depolarization-evoked release of [(3)H]noradrenaline.

Incidence and Factors Associated With Concussion Injuries at the 2011 to 2014 South African Rugby Union Youth Week Tournaments.

Objective:To determine the concussion incidence and to identify factors associated with concussion in South African youth rugby union players. Design:Prospective cohort study. Setting:Injury surveillance was completed at the South African Rugby Union Youth Week tournaments (under-13, under-16, and under-18 age groups). Participants:South African youth rugby union players. A total of 7216 players participated in 531 matches between 2011 and 2014. Interventions:None. Main Outcome Measures:Concussion incidence was calculated per 1000 player-match-hours with 95% CIs. Poisson regression was used to calculate the incidence rate ratio (IRR) between factors (age, time period, playing position, and activity at the time of concussion) potentially associated with concussions. Results:The concussion incidence was 6.8/1000 player-match-hours (95% CI, 5.5-8.1) across all age groups. Under-13s (IRR, 1.5; P = 0.09) and under-16s (IRR, 1.7; P = 0.03) had higher concussion incidence rates than the under-18 age group. The incidence was higher in the third (IRR, 2.1; P = 0.04) and fourth (IRR, 2.5; P = 0.01) quarters of matches compared with the first quarter. Sixty-two percent of concussions occurred in the tackle situation. The tackler had a 4-fold greater concussion rate (IRR, 4.3; P < 0.001) compared with the ball carrier. The hooker and loose forwards had higher incidence rates than several other player positions (P < 0.05). Conclusions:The reported concussion incidence falls within the broad range previously reported in youth rugby. The evidence highlighted in this study may contribute to targeted concussion prevention strategies and provide a baseline against which the effectiveness of future interventions can be measured.

Video analysis of concussion injury mechanism in under-18 rugby

Background Understanding the mechanism of injury is necessary for the development of effective injury prevention strategies. Video analysis of injuries provides valuable information on the playing situation and athlete-movement patterns, which can be used to formulate these strategies. Therefore, we conducted a video analysis of the mechanism of concussion injury in junior-level rugby union and compared it with a representative and matched non-injury sample. Methods Injury reports for 18 concussion events were collected from the 2011 to 2013 under-18 Craven Week tournaments. Also, video footage was recorded for all 3 years. On the basis of the injury events, a representative ‘control’ sample of matched non-injury events in the same players was identified. The video footage, which had been recorded at each tournament, was then retrospectively analysed and coded. 10 injury events (5 tackle, 4 ruck, 1 aerial collision) and 83 non-injury events were analysed. Results All concussions were a result of contact with an opponent and 60% of players were unaware of the impending contact. For the measurement of head position on contact, 43% had a ‘down’ position, 29% the ‘up and forward’ and 29% the ‘away’ position (n=7). The speed of the injured tackler was observed as ‘slow’ in 60% of injurious tackles (n=5). In 3 of the 4 rucks in which injury occurred (75%), the concussed player was acting defensively either in the capacity of ‘support’ (n=2) or as the ‘jackal’ (n=1). Conclusions Training interventions aimed at improving peripheral vision, strengthening of the cervical muscles, targeted conditioning programmes to reduce the effects of fatigue, and emphasising safe and effective playing techniques have the potential to reduce the risk of sustaining a concussion injury.

Inflammatory and apoptotic signalling pathways and concussion severity: a genetic association study

ABSTRACT The objective was to investigate the relationship between IL-1B rs16944, IL-6 rs1800795, and CASP8 rs3834129 genetic polymorphisms and concussion severity. Rugby players from high school, senior amateur, and professional teams completed a concussion severity questionnaire and donated a DNA sample. Participants (n = 163) were split into symptom severity groups around the median number and duration of symptoms. The frequency of participants with high symptom counts (more than five symptoms) increased across the IL-1B (C/C: 35%; C/T: 51%; T/T: 56%; P = 0.047) and the IL-6 (C/C: 31%; C/G: 44%; G/G: 58%; P = 0.027) genotypes. The C–C inferred interleukin allele construct frequency, created from combining the IL-1B and IL-6 genotype data, was lower in participants reporting a high symptom count (18%), compared to those with a low symptom count (fewer than six symptoms, 36%, P = 0.002). Similarly, the C–C inferred interleukin allele construct frequency was lower in those reporting prolonged symptom duration (more than one week, 16%), as opposed to short symptom duration (less than one week, 34%, P = 0.015). This study provides evidence of novel inflammatory pathway genetic associations with concussion severity, which supports the hypothesis implicating neuroinflammation in the development of concussion symptoms.

The association between COMT rs4680 and 5-HTTLPR genotypes and concussion history in South African rugby union players

ABSTRACT The objective was to investigate the relationship between Catechol-O-methyltransferase (COMT) rs4680 and serotonin-transporter-linked polymorphic region (5-HTTLPR) genotypes with concussion history and personality traits. Rugby players (“all levels”: n = 303), from high schools (“junior”, n = 137), senior amateur, and professional teams (“senior”, n = 166), completed a self-reported concussion history questionnaire, Cloninger’s Tridimensional Personality Questionnaire, and donated a DNA sample. Participants were allocated into control (non-concussed, n = 140), case (all) (previous suspected or diagnosed concussions, n = 163), or case (diagnosed only) (previous diagnosed concussion, n = 140) groups. COMT rs4680 Val/Val genotypes were over-represented in controls in all levels (P = 0.013, OR:2.00, 95% CI:1.15–3.57) and in juniors (P = 0.003, OR:3.57, 95% CI:1.45–9.09). Junior Val/Val participants displayed increased “anticipatory worry” (P = 0.023). The 5-HTTLPR low expressing group was under-represented in controls when all levels were considered (P = 0.032; OR:2.02, 95% CI:1.05–3.90) and in juniors (P = 0.021; OR:3.36, 95% CI:1.16–9.72). Junior 5-HTTLPR low and intermediate expressing groups displayed decreased “harm avoidance” (P = 0.009), “anticipatory worry” (P = 0.041), and “fear of uncertainty” (P < 0.001). This study provides preliminary indications that personality associated genetic variants can influence concussion in rugby.

Toxic tau: The TAU gene polymorphisms associate with concussion history in rugby union players

OBJECTIVES Concussion is a brain injury that occurs when biomechanical forces are transmitted to the head region resulting in neurological deficits. The accumulation of tau protein in autopsies of athletes with multiple concussions implicates tau in concussion-associated neurodegeneration. The TAU rs2435211 (C>T) and rs2435200 (G>A) polymorphisms are involved in pathological tau expression and neurodegenerative disease risk. The aims of this study were to investigate the associations of TAU (rs2435211, rs2435200) polymorphisms with concussion history and sustaining multiple concussions in rugby. DESIGN In total, 140 non-concussed controls and 163 previously concussed participants (all cases group, N=163; clinically diagnosed, N=140; multiple concussed, N=87) were recruited from high school (N=135, junior), club and professional rugby teams (N=166, senior). METHODS Participants were genotyped for TAU rs2435211 and rs2435200 polymorphisms. RESULTS In seniors, the rs2435200 AA genotype was significantly over-represented in the control group compared to the multiple concussed subgroup (P=0.033, control: 25%, N=16, multiple concussed: 11%, N=6; OR: 0.34, 95% CI 0.12-0.96). While the AG genotype was significantly under-represented in the control compared to multiple concussed (P=0.024, control: 45%, N=29, multiple concussed: 63%, N=36; OR: 2.34, 95% CI 1.11-4.95). The inferred TAU (rs2435211 C>T-rs2435200 G>A) T-G haplotype was significantly under-represented in the control (19%, N=12) compared to the all cases group (30%, N=28, P=0.031). CONCLUSIONS The TAU-associated neurodegenerative pathway was implicated as a potential pathophysiological mechanism underlying concussion in seniors. In future, the identification of TAU polymorphisms associated with concussion risk may assist clinical management and reduce risk of severe complications.