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Are Concussed Athletes Being Returned To Play While Still Cognitively Impaired?

27.7% of concussed athletes in study failed post-exertional neurocognitive test despite reporting no symptoms and return to baseline

A significant number of concussed student-athletes may be cleared to return to play despite being cognitively impaired, finds an important new study.1

Jigsaw puzzle of head with two missing pieces

Of concussed student-athletes who reported no symptoms and had returned to baseline on computerized neurocognitive tests taken before beginning graduated return to sports protocol,2 researchers found that more than a quarter (27.7%) exhibited declines in verbal and visual memory on the tests following moderate exercise. 

The findings prompted the study's authors, led by sports concussion neuropsychologist Neal McGrath, Ph.D. of Sports Concussion New England, to recommend that neurocognitive testing become an "integral component of the athletic trainer's post-exertion evaluation protocol and that student-athletes should not be cleared for full contact activity until they are able to demonstrate stability, particularly in memory functioning, on such post-exertion neurocognitive concussion testing."

Study details

Researchers tested 54 students from 15 schools and one junior hockey program who had suffered sport-related concussion and one or more clinically significant decline in neurocognitive performance at the initial post-injury neurocognitive test session, and who had valid neurocognitive baseline tests within the past two years.  After being determined by their athletic trainer to be symptom-free and to have returned to baseline on their neurocognitive tests, the student-athletes then participated in a physical exertion protocol at their respective schools or sports club that included 15-25 minutes of moderate aerobic exercise (e.g. stationary cycling, treadmill running, elliptical) and/or non-contact sport-specific activities (e.g. dribbling, skating).  Following a 5-to-10 minute rest period, they then completed a post-exertion neurocognitive test. 

Based on post-exertion (PE) neurocognitive performance, 15 student-athletes (27.7%) were categorized into the  PE-Fail group (i.e. had declines in cognitive performance) and 39 student-athletes were categorized into the PE-Pass Group.  PE-Fail subjects scored significantly lower on tests of verbal and visual memory.  Group differences on measures of processing speed (visual motor speed and reaction time) were not statistically significant, nor did the PE-Fail subjects score significantly higher on the Post-Concussive Symptom Scale (PCSS).

The fact that the decline in verbal and visual memory in the PE-Fail group was not associated with symptom recurrence, said the study, "suggests that computerized neurocognitive testing during post-exertion evaluation may be uniquely sensitive to detect changes in clinical status that would identify recovering student-athletes who should not yet resume contact sports activity."

That post-concussive symptom severity on initial post-concussion neurocognitive testing and after exertion was not associated with PE test failure also "suggests that the neurocognitive decline during post-exertion testing observed in this study may reflect incomplete recovery unrelated to many of the clinical variables traditionally associated with concussion," observed McGrath. 

Post-exertional testing recommended 

As the study notes, "in the clinical management of sports-related concussion, it has long been the standard of care that athletes should not return to contact sports action and risk further injury until they are symptom-free. Once an athlete is asymptomatic at rest, a graduated return to sports activity3 is recommended, beginning with light non-contact exercise and progressing to full contact sports action.  If post-concussive symptoms re-emerge during the course of this return to play regimen, the athlete's recovery is considered incomplete and additional recovery time under conditions of controlled activity is recommended.  An athlete should not return to play until he or she has demonstrated the ability to remain symptom-free with full physical exertion."

Up to now, as McGrath notes, "post-exertion protocols for athletic trainers and team physicians have generally consisted of supervised workouts with general monitoring for recurrence of post-concussive symptoms using self-report data along with brief clinical sideline testing. However, such protocols have not typically included computerized neurocognitive reassessment. Given the unreliable nature of self-reported symptoms in athletes 2 a group typically motivated to return to play and minimize symptoms, the sensitivity of computerized neurocognitive testing to incomplete recovery and the importance of identifying any indicators that an athlete may not remain stable in his/her baseline functioning prior to return to contact sports action, post-exertion neurocognitive testing appears to be a logical tool to consider." 

"Our thinking," said McGrath, "is that since exercise is known to cause recurrence of symptoms in some athletes who may not be fully recovered, and since neurocognitive testing has been shown to reveal2 persisting cognitive deficits in athletes who say or feel that they are symptom-free, any significant decline in post-exercise cognitive test scores for those athletes who have reached the point of feeling fully symptom-free with resting neurocognitive scores that are back to baseline would indicate that more recovery time is needed before returning to contact sports action. We would follow those athletes until their post-exercise neurocognitive test scores remain stable at baseline levels before clearing them to return to play." 

Important study

The study "is a start in knowing more about the different aspects of recovery that should be monitored, including symptom reports by athletes, cognitive performance, balance, emotional and behavioral status, and neurometabolic/neuroimaging information, among others," said sports concussion neuropsychologist and MomsTEAM expert Rosemarie Scolaro Moser, Ph.D. These aspects may 'recover' or change at different rates."

"It is always good to obtain a 'final' testing after physical exertion and completion of the gradual return to play protocol,3 so that it may serve as a new baseline. Overall, I think it is a great study we should not ignore. It also may be helpful to apply when confronted with the phenomenon of athletes who may not honestly report their symptoms in order to return to sports," Moser said.

Study limitations

"One obvious limitation" of the study, McGrath conceded, was the relatively small sample size.  Because the sample was limited to high school/junior high-aged student-athletes, the findings are also not generalizable to other age groups, and, because the female sub-sample was quite small, a direct comparison of male and female student-athletes was not undertaken. In addition, the study did not include a non-concussed control group, which would have minimized potential threats to internal validity. As a result, the study authors called for future studies to include greater number of female student-athletes to determine whether male and female PE-Fail subjects exhibit similar cognitive deficit profiles.

1.  McGrath N, Dinn WM, Collins MW, Lovell MR, Elbin RJ, Kontos AP.  Post-exertion neurocognitive test failure among student-athletes following concussion.  Brain Injury 2013;27(1):103-113.

2.  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)

3.  Consensus Statement on Concussion in Sport: the 3rd International Conference on Concussion in Sport held in Zurich, November 2008.  Br. J. Sports Med. 2009:43:i76-i84

Posted February 7, 2012; updated July 13, 2013