Home » Health & Safety Channel » Effects of Concussion on Higher Cognitive Function Persist In Teens, Study Says

Effects of Concussion on Higher Cognitive Function Persist In Teens, Study Says

Study suggests that adolescents may be particularly vulnerable to effect of mTBI on developing brain

Concussed adolescents have difficulty recovering the ability for high level thinking after injury and may require extended recuperation before full recovery of so-called 'executive function' is achieved, a new study finds. [1]

Active brain

Researchers at the University of Oregon and University of British Columbia found that executive function was disrupted in concussed adolescents for up to 2 months after injury when compared to healthy control subjects.  

The concussed teens had difficulties ignoring irrelevant but conflicting information when taking the Attentional Network Test (ANT), a widely used and well-studied test probing attention by assessing the relative change in reaction time to different stimuli, and that the impairment continued for up to 2 months post-injury, well beyond the time they reported being symptom-free on a concussion inventory, which typically occurred between 2 weeks and 1 month after injury, about twice as long as the impairment found in young adults. 

The  concussed teens also performed significantly worse than their uninjured peers on a Task-Switching Test (TST), which, as its name suggests, tests the ability to flexibly switch between competing task or stimulus-response rules, which previous studies had found to be highly sensitive to mild traumatic brain injury (mTBI) in adults but had not been studied in the concussed adolescent population.  

"The results of this study suggest," said lead author David Howell of the Department of Human Physiology at the University of Oregon, "that tests which isolate components of executive function (ANT and TST) are sensitive to the effects of concussion in adolescents and reveal deficiencies that may last for at least 2 months after concussion.  These data suggest that executive function testing may be a highly useful assessment to identify disturbances and track recovery following concussion for the adolescent population." 

"This was a well-conducted study which adds further support to using neuropsychological testing as a supplement to the management of sport-related concussion," said William P. Meehan, III, a MomsTEAM concussion expert, and Director of both the Sports Concussion Clinic and the Micheli Center for Sports Injury Prevention in the Division of Sports Medicine at Boston Children's Hospital.

The study also suggests, said Dave Ellemberg, Ph.D., a Professor in the Department of Kinesiology at the University of Montreal, that expensive baseline neuropsychological testing is not required to determine cognitive impairment from concussion, and that comparing an athlete's post-concussion neuropsychological test results to those of athletes of the same age and gender (e.g. 'normative values') may be enough as a diagnostic tool. Ellemberg viewed the study as lending "strong confirmation" to a pair of 2012 studies [2,3] which concluded that clinicians, can, in most cases, identify the same cognitive impairments in a concussed athlete by using normative neurocognitive values as by comparing their post-concussion performance to individual pre-injury baselines.

Teens uniquely vulnerable to concussion? 

Because the frontal areas of the brain believed to play a role in the ability to focus attention on relevant stimuli while filtering out extraneous information are among the last to develop, the study authors speculated that this region of the adolescent brain may be more susceptible to concussion and deficits may last longer in this population than older age groups.

Included among the studies they cited in support of the view that teens may be especially vulnerable was a 2012 study [4] in which Ellemberg and his colleagues found that adolescents displayed persistent neuropyschological deficits at least 6 months after concussion and were more sensitive to the effects of concussion than adults. 

Like the current study, the authors of the 2012 study speculated that the adolescent age group may be more vulnerable to concussion effecting the frontal region of the brain responsible for working memory and executive function, which is undergoing a period of rapid growth in adolescence.

What constitutes 'full recovery'?

Commenting on the study, sports concussion neuropsychologist and MomsTEAM expert, Rosemarie Scolaro Moser, PhD. said that, "Howell and colleagues have addressed a very important issue in return to play: when is the athlete fully recovered from concussion? Although their study is small in nature and has its limitations, it is an addition to the current research that suggests that symptom report is not enough [5] to determine that athletes have fully recovered."

"In adults, we have typically thought that most athletes recover from uncomplicated concussion in 10 days or so. Yet, in a 2010 study (6) demonstrated that brain metabolites such as creatine and n-acetylaspartate normalized after approximately one month, even when athletes reported feeling back to normal by day 15 or earlier. We know that youth are more vulnerable to the effects of concussion. The Howell study joins others [7-11] in its call to keep kids out longer than is current practice." 

"All the more reason to not rush kids back to school or sports and to give their brains time to heal and restabilize. Thus, concussion healthcare professionals need to advocate for these athletes to provide them with the appropriate medical leave and academic accommodations, even in the face of insistent parents, coaches, and school personnel who may want to rush them back to their usual activity," says Moser.

1. Howell D, Osternig L, Van Donkelaar P, Mayer U, Chou L.  Effects of Concussion on Attention and Executive Function in Adolescents.  Med Sci Sports Exer. 2013;45(6):1023-1029.

2. Echemendia R, Bruce J, Bailey C, Sanders J, Arnett P, Vargas G. The Utility of Post-Concussion Neuropsychological Data in Identifying Cognitive Change Following Sports-Related MTBI in the Absence of Baseline Data.  Clin Neuropsy 2012;26(7):1077-1091.

3. Schmidt J, Register-Mihalik J, Mihalik J, Kerr Z, Guskiewicz K. Identifying Impairments after Concussion: Normative Data vesus Individualized Baselines. Med & Sci Sports & Exer. 2012;44(9):1621-1628.

4. Baillargeon A, Lassonde M, Leclerc S, Ellemberg D. Neuropsychological and neurophysiological assessment of sport concussion in children, adolescents and adults. Brain Injury 2012;26(3):211-220.

5.  Sandel N, Lovell M, Kegel N, Collins M, Kontos A. The Relationship Of Symptoms and Neurocognitive Performance to Perceived Recovery From Sports-Related Concussion Among Adolescent Athletes. Applied Neuropsychology: Child. 2012; DOI:10.1080/21622965.201 2.670680 (published online ahead of print 22 May 2012)(accessed June 5, 2012) 

6. Vagnozzi R, et al. Assessment of metabolic brain damage and recovery following mild traumatic brain injury: a multicentre, proton magnetic resonance spectroscopic study in concussed patients. Brain 2010;11:133. DOI: 10.1093/brain/awq200 

7. Moser RS, Schatz P, Jordan BD. Prolonged Effects of Concussion in High School Athletes. Neurosurgery 2005; 57(2):300-306.

8.  Schatz P, Moser RS, Covassin T, Karpf R. Early Indicators of Enduring Symptoms in High School Athletes with Multiple Previous Concussions. Neurosurgery 2011: 000.

9.  McCrea M, Hammeke T, Olsen G, Leo P, Guskiewicz K. Unreported concussion in high school football players - Implications for prevention. Clin J of Sport Med 2004;14:13-17. 10.   Neary J. et. al. Cerebrovascular Reactivity Impairment after Sport-Induced Concussion, Med Sci Sports Exer 2011;43(12): 2241-2248.

10.  Maugans T, Farley C, Altaye M, Leach J, Cecil K.  Pediatric Sports-Related Concussion Produces Cerebral Blood Flow Alterations. Pediatrics 2012;129(1)(doi: 10.1542/peds.2011-2083)(accessed March 30, 2012)

Posted June 5, 2013; revised June 8, 2013 to include Dr. Moser's comments; revised further on June 17, 2013 to reflect Dr. Ellemberg's comments and include studies at footnotes 2 & 3.