- Vanderbilt University School of Medicine, Nashville, TN, USA
- Vanderbilt Sports Concussion Center and Department of Neurological Surgery, Medical Center, Nashville, TN, USA
Scott L. Zuckerman
Vanderbilt Sports Concussion Center and Department of Neurological Surgery, Medical Center, Nashville, TN, USA
DOI:10.4103/2152-7806.102945Copyright: © 2012 Zuckerman SL. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
How to cite this article: Zuckerman SL, Lee YM, Odom MJ, Solomon GS, Forbes JA, Sills AK. Recovery from sports-related concussion: Days to return to neurocognitive baseline in adolescents versus young adults. Surg Neurol Int 27-Oct-2012;3:130
How to cite this URL: Zuckerman SL, Lee YM, Odom MJ, Solomon GS, Forbes JA, Sills AK. Recovery from sports-related concussion: Days to return to neurocognitive baseline in adolescents versus young adults. Surg Neurol Int 27-Oct-2012;3:130. Available from: http://sni.wpengine.com/surgicalint_articles/recovery-from-sports-related-concussion-days-to-return-to-neurocognitive-baseline-in-adolescents-versus-young-adults/
Background:Sports-related concussions (SRC) among high school and collegiate athletes represent a significant public health concern. The Concussion in Sport Group (CIS) recommended greater caution regarding return to play with children and adolescents. We hypothesized that younger athletes would take longer to return to neurocognitive baseline than older athletes after a SRC.
Methods:Two hundred adolescent and young adult athletes who suffered a SRC were included in our clinical research cohort. Of the total participants, 100 were assigned to the 13-16 year age group and 100 to the 18-22 year age group and were matched on the number of prior concussions. Each participant completed baseline and postconcussion neurocognitive testing using the Immediate Post-Concussion assessment and Cognitive Testing (ImPACT) test battery. Return to baseline was defined operationally as post-concussion neurocognitive and symptom scores being equivalent to baseline using reliable change index (RCI) criteria. For each group, the average number of days to return to cognitive and symptom baseline were calculated. Independent sample t-tests were used to compare the mean number of days to return to baseline.
Results:Significant differences were found for days to return to baseline between 13-16 year olds and 18-22 year olds in three out of four neurocognitive measures and on the total symptom score. The average number of days to return to baseline was greater for 13-16 year olds than for 18-22 year olds on the following variables: Verbal memory (7.2 vs. 4.7, P = 0.001), visual memory (7.1 vs. 4.7, P = 0.002), reaction time (7.2 vs. 5.1 P = 0.01), and postconcussion symptom scale (8.1 vs. 6.1, P = 0.026). In both groups, greater than 90% of athletes returned to neurocognitive and symptom baseline within 1 month.
Conclusions:Our results in this clinical research study show that in SRC, athletes 13-16 years old take longer to return to their neurocognitive and symptom baselines than athletes 18-22 years old.
Keywords: Age, concussion, immediate post-concussion assessment and cognitive testing, mild traumatic brain injury, sports
In the United States, 1.7-3.8 million traumatic brain injuries (TBI) occur each year, and over 300,000 are due to sports and recreational activities.[
Early studies conducted in the 1980s are believed to have overestimated concussion incidence, reporting rates in high school football to be as high as 15-20% compared to 10% at the collegiate level[
In 2008, the third meeting of the Concussion in Sport Group (CIS) was held in Zurich.[
CIS delineated several “modifying” factors that influence investigation and management of concussions and prolonged symptoms, such as number of previous concussions, prolonged loss of consciousness, medication status, and other biopsychosocial factors. The consensus reached was that age <18 years is considered a modifying factor. The international group concluded: “Because of the different physiological response and longer recovery after concussion and specific risk related to head impact during childhood and adolescence, a more conservative return to play approach is recommended. It is appropriate to extend the amount of time of asymptomatic rest and/or the length of the graded exertion in children and adolescents.”[
To date, two papers have addressed empirically age-related concussion outcome. In 2003, Field et al.,[
More recently, Baillargeon et al.[
Athletic trainers and team physicians are forced with the challenging situation of deciding when to return an athlete to play. Guidelines for return to play (RTP) have been extensively published,[
In this clinical research study we endeavored to assess acute neurocognitive and symptom recovery trajectories after SRC between two different age groups. We hypothesized that younger athletes would take longer to return to neurocognitive baseline than older athletes after a SRC.
Institutional Review Board approval (IRB) was obtained prior to data collection. Our study was clinical, retrospective, and observational in nature. Participants were recruited from high schools and colleges in the Western Pennsylvania area from 2009 to 2011 as part of a regional neurocognitive testing program. Following written, informed consent (by the athlete or his/ her parent/guardian), all athletes underwent baseline neurocognitive testing as part of routine athletic care. Baseline testing was completed prior to each athlete's respective season. Baseline neurocognitive testing was conducted at each athlete's respective school, in a controlled environment (group setting) with minimal distractions. Postconcussion testing was conducted individually in controlled medical settings.
Selection of participants
Following head injuries, concussion was diagnosed based on the on-field presentation of one or more of the following signs or symptoms: (1) self-reported postconcussive symptoms, such as lethargy, fogginess, headache, etc., (2) alteration in mental status, (3) loss of consciousness, or (4) amnesia. The initial concussion diagnosis was made by a sports medicine athletic trainer or a team physician of one of the competing teams. Following the recommendations of the CIS consensus guidelines, no grading system was utilized for concussion severity.
The inclusion criteria for the current study was (1) age 13-16 years or 18-22 years at time of concussion, (2) participating in high school or collegiate athletics, (3) valid preparticipation baseline neurocognitive test data, (4) valid completion of up to two postconcussion neurocognitive testing data points within 30 days of the concussion (defined operationally as an ImPACT impulse control composite score of >30),[
Matching of age cohorts
The final sample of the study participants was formulated by the following process. From the aforementioned database of athletes, 740 participants who previously completed baseline ImPACT testing and suffered a SRC were identified. Of these 740 athletes, 126 were outside of the age range of our study, and 112 had a history of special education, speech therapy, repeated year of school, or learning disability, and were excluded from the study. Of the remaining 502 eligible participants who sustained a concussion during the study period, 200 participants (100 in the 13-16 year range and 100 in the 18-22 year range) who had completed at least two postconcussion ImPACT tests within 30 days of the concussion were matched based on the number of prior concussions, and subsequently included in the study. The flow-chart showing the patient inclusion into the study is included in
Data collection and neurocognitive/symptom assessments
We chose to use the ImPACT test battery to obtain baseline neurocognitive test/symptom data. ImPACT is a commercially available computerized test for SRC that provides symptom and neurocognitive test data.[
Patients in this clinical research study were administered up to two postconcussion ImPACT tests. These tests were performed on separate days within 30 days of concussion. In this clinical research study, testing was dictated by clinical factors as opposed to a standardized research protocol. The primary dependent variable was operationally defined as the number of days until the postconcussion test scores returned to the participant's own baseline for all of the neurocognitive and symptom indexes. Utilizing a reliable change index (RCI) set at the 80% confidence interval,[
Descriptive statistics are reported as mean and standard deviation for continuous variables and as frequency and proportion for categorical variables. Means and standard deviations of the ImPACT composite scores for both 13-16 year old and 18-22 year old groups were assessed at baseline and at both postconcussion test dates. For participants returning to baseline within the 30-day study period, the number of days to return to baseline for each of the ImPACT neurocognitive and symptom scores was computed. For each composite score, the mean number of days to return to baseline was compared between the two age groups using an independent samples t-test. The significance of the difference between the 13-16 year olds and the 18-22 year olds for these measures was evaluated at α = 0.05. None of the participants included in the final analyses had any missing data. Statistical analyses were performed by using IBM SPSS Statistics, Release Version 20.0.0 (IBM Corp., 2011, Chicago, IL,
The 200 participants in our cohort allowed for exactly 100 participants in the 13- to 16-year-old age group and 100 participants in the 18- to 22-year-old age group.
The type of sport played also was not a controlled variable in this study. Among the 13- to 16-year-old males, approximately 76% were football players. The females in this younger age group comprised primarily soccer (33%), basketball (21%), and cheerleading (21%) athletes. In the 18-22 year group, football accounted for 59% of the male athletes while 16% played basketball and 13% played soccer. Females in the 18- to 22-year-old group came from the sports of soccer (36%), softball (20%), basketball (16%), and cheerleading (6%).
Baseline neurocognitive and symptom scores
Days to return to baseline scores
The results for the average number of days taken by 13- -16 year olds and 18-22 year olds to return to baseline scores are summarized in
Paired t-tests (α=0.5) were used to evaluate the significance of the differences between the 13-16 year- old and 18-22 year-old cohorts. The average number of days to return to baseline was greater for 13-16 year olds than for 18-22 year olds on verbal memory (7.2 vs. 4.7, P =0.001), visual memory (7.1 vs. 4.7, P = 0.002), reaction time (7.2 vs. 5.1 P = 0.01), and postconcussion symptom scale (8.1 vs. 6.1, P = 0.026). The difference between groups on visual motor (processing) speed (6.8 vs. 5.3, P = 0.063) bordered on, but did not reach, the conventional level of statistical significance.
We endeavored to assess acute neurocognitive and symptom recovery differences after SRC between two different age groups, hypothesizing that younger athletes would take longer to return to neurocognitive baseline than older athletes. Our results show that in this cohort, athletes 13-16 years old took several days longer to return to their neurocognitive and symptom baselines than athletes 18-22 years old. These results support the prior findings that younger athletes may take longer to recover to neurocognitive and symptom baseline than older athletes. We found baseline differences between the age groups on three of the neurocognitive indexes. This is not a surprising finding, since baseline normative values on ImPACT vary as a function of age, and normative values are age based. Further, the disparity between groups at baseline, in the vast majority of cases, has no direct effect on the amount of time it may take to return to an individual's baseline scores.
Our findings, despite being a retrospective clinical research study, offer some methodological advantages compared to the preexisting studies. Both prior studies[
Our study suffers several limitations. This was not a prospective, control group study driven by a research protocol, and postconcussion testing was not conducted at regularly scheduled intervals. Whereas the two prior studies utilized a standardized follow-up schedule for neurocognitive testing, our study collected clinical, retrospective data, where athletes’ time of testing was mandated clinically. Our study describes the real-world follow-up of concussion, but without a standardized protocol and appropriate controls, our data must be viewed in the clinical context in which it was collected. The difference between the days to the first postconcussion test for the younger group (M = 5.0 days, SD = 4.6 days) and the older group (M = 3.3 days, SD = 3.4) was found to be statistically significant (P = 0.003). Second, our data analysis was completed retrospectively, in a cross-sectional manner. Third, groups were not matched on the variables of gender or sport. Finally, we did not assess athletes formally for effort using traditional clinical neuropsychological tests. Instead, we used the rule proposed by Lovell as a proxy for a formal effort test.
Finally, we must emphasize that the current results do not reflect or indicate that athletes were cleared for a return to play postconcussion. This was not intended to be a “return to play” study. Neurocognitive test results and symptom scores are one piece of a larger return to play clinical decision-making process. Multiple factors must be taken into consideration when evaluating a player's safety to return to the field.[
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