The ability of teens, and, in the case of younger athletes, their parents, to accurately recall the severity of symptoms experienced before after a mild traumatic brain injury (mTBI) injury is subject to a "good old days" bias and declines dramatically over time, says a new study, which suggests that using symptom ratings of pre-injury functioning obtained as soon as possible after injury might result in a 5 to 7-fold improvement in a clinician's identification of patients who have clinically recovered from concussion.

Canadian researchers compared data obtained from 412 parents of patients aged 2 to 12 and adolescents aged 13 to 18 who completed a post-concussion symptom inventory in a hospital Emergency Department (ED) immediately after mTBI and at 1- and 3-month followup visits. They found that retrospectively reported pre-injury symptoms decreased by 80% from the ED to 1-month post-injury, and that the number of children rated by their parents as having no pre-injury symptoms jumped from 35% in the ED to 75% at 1 month and 83% at 3 months.

The study was published on line in the Archives of Clinical Neuropsychology. ^[1] 

While the majority of symptoms associated with mTBIs resolve within days to weeks, approximately 11% of pediatric patients remain symptomatic at 3 months post injury and are considered to be experiencing post-concussion syndrome; a disruption of normal functioning, even if it only lasts 1 to 3 months, is significant, especially in a child who is developing and expected to be acquiring new skills.

Because there are no baseline data for the vast majority of children and adolescents (although baseline testing is becoming more common at the high school and pre-high school level as well), tracking recovery from mTBI is primarily based on the resolution of subjectively reported symptoms in comparison with pre-injury levels of functioning, with clinicians trusting that the retrospective account of functioning prior to injury is accurate.  

"Good old days" bias

Dr. Brooks and his colleagues theorized, however, that subjective reporting of pre-injury functioning by children and teens would be vulnerable to the same "good old days" bias that effects subjective reporting by adults: the normal tendency of individuals to selectively remember being healthier in the past and to fail to remember having health problems, which, in the context of mTBI, could play a role in the perceived persistence of post-concussion symptomatology by minimizing the likelihood that such symptoms existed prior to the injury and attributing the current symptoms directly to the injury.

"Disentangling the effects of concussion, accounting for pre-existing problems, and monitoring recovery over time is truly a tour de force for any clinic[ian]," writes Brooks, but "as this study clearly demonstrated, the retrospective recall of [such] symptoms is subject to bias as early as 1-month post-injury."

The implications for health care professionals in managing concussions of a finding of the "good old days" bias, he asserted, were "tangible, demonstrable, and quantifiable. ... Using the pre[injury] symptoms reported in the ED, rather than retrospectively reported at follow-ups, results in up to one-third fewer patients being deemed to have symptomatolgy that exceeds their baseline.  Considering the prevalence and healthcare costs associated with an mTBI, this 5-7-fold improvement in a clinician's identification of a patient's return to pre[injury] functioning would be substantial," Dr. Brooks suggests.

Dr. Brooks and his colleagues recommend that clinicians who assess patients following an mTBI obtain baseline ratings of functioning as soon as possible after injury, and use the earliest baseline symptom ratings as a point of comparison for determining recovery from an mTBI.

Study limitations

The study authors identified several limitations:

1. preinjury symptoms were not rated by adolescents at the time of injury; only parent-proxy ratings were available.
2. although the post-concussion symptom inventory (PCSI) can be administered to children as young as 5 years, ratings by children 5-12 years old were not obtained, with only parent-proxy ratings available for younger patients
3. Ratings of symptoms at the 1- and 3-month follow-ups were done over the phone, which could potentially change pre-injury symptom reporting.
4. Not every patient provided retrospective ratings at 3 months post-injury.
5. The study did not employ a control group.
6. The study did not include measures of performance validity or documentation of whether any families were involved in ligitation during their enrollment in the study.

Cautionary notes

Parents need to keep in mind, however, that, while post-concussion symptom scales remain what Dr. Brooks called the "gold standard" for determining outcome from concussion, that symptoms have returned to pre-injury baseline does not mean, in and of itself, that a child or teen is ready to return to play.

A study by researchers at the University of Pittsburgh Medical Center (UPMC),^[2] found that, when athletes gauge their own readiness to return-to-play, they rely most heavily on the absence of somatic (e.g. physical) symptoms such as headache, vomiting and visual disturbances - which are more apparent and easier for the athlete or those around them to directly observe - and much less on the more elusive and subtle symptoms of concussion such as "fogginess," difficulty concentrating or remembering, and slowed reaction time - symptoms which are harder for the athlete to detect. They also found that athletes' awareness of their cognitive decline after concussion is limited.

"Relying solely on adolescents' self-reported symptoms for return-to-play and concussion management decisions is ill-advised as their perceptions may include only a small subset of the deficits commonly seen after concussion. These findings further highlight the importance of using objective measures for the assessment of concussion," said lead author of the study, Natalie Sandel, B.S., of the Department of Neuroscience and Dietrich School of Arts and Sciences at the University of Pittsburgh.

In a second study ^[3] reseachers from UPMC and Vanderbilt found that among female high school cheerleaders with diagnosed concussion who reported after concussion being asymptomatic, a third (33%) had at least one abnormal indicator on the neurocognitive component of their ImPACT test compared to their baseline scores.

"This study demonstrates that even athletes who report being symptom-free may continue to exhibit neurocognitive deficits of which they are either unaware or are failing to report," said UPMC's Mark Lovell, PhD. "Furthermore, our data suggest that if neurocognitive testing is unavailable, then the treating physician should be cautious in returning athletes to play based on their self-report of symptoms alone." 

A third recent study ^[4] provides additional support for the view that athletes should not be returned to play based solely on reporting being asymptomatic. It found that, among concussed student-athletes who reported no symptoms and even had returned to baseline on computerized neurocognitive tests taken before beginning a graduated return to sports protocol,^[5] which requires that athletes be asymptomatic and have returned to baseline, more than a quarter (27.7%) exhibited declines in verbal and visual memory on the tests after moderate exercise.

Those findings prompted the authors of that study, 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." Such post-exertion testing is not currently the standard of care as part of return to play guidelines.

Given these studies, William P. Meehan, III, MomsTEAM expert and Director of the Sports Concussion Clinic in the Division of Sports Medicine at Boston Children's Hospital, argues that the best practice is to "institute a symptom-free waiting period after symptom resolution and return of neurocognitive function."

"What we are seeing is that the effects of concussion in youth are lasting longer and are more enduring than we have thought," says Rosemarie Scolaro Moser, PhD, Director of the Sports Concussion Center of New Jersey. "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." 

1. Brooks BL, Kadoura B, Turley B, Crawford S, Mikrogianakis A, Barlow KM.  Perception of Recovery After Pediatric Mild Traumatic Brain Injury Is Influenced by the "Good Old Days" Bias: Tangible Implications for Clinical Practice and Outcomes Research.  Arch Clin Neurospych. 2013;doi:10.1093/arcclin/act083 (epub November 5, 2013)

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. Lovell MR, Solomon GS. Neurocognitive Test Performance and Symptom Reporting in Cheerleaders in Concussions. J Pediatrics 2013. DOI: 10.1016/jpeds.2013.05.061 (epub September 2013).

4. 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.