Effects of Concussion on Attention and Executive Function in Adolescents

David Howell; Louis Osternig; Paul Van Donkelaar; Ulrich Mayr; Li-Shan Chou

Disclosures

Med Sci Sports Exerc. 2013;45(6):1030-1037. 

In This Article

Abstract and Introduction

Abstract

Background: Head trauma in adolescents has been linked with deficits in attention and executive function that can compromise the performance of everyday tasks. Although previous research has examined this issue using computerized neuropsychological testing, little work has been done using laboratory-based measurements of attention and executive function in this population. A longitudinal analysis of recovery patterns of these measures among adolescents is central to understanding the effects of concussions across the age spectrum.

Purpose: This study prospectively and longitudinally examined laboratory-based measures of attention and executive function in concussed adolescents sequentially during a 2-month period after injury.

Methods: Two measures of attention and executive function, the Attentional Network Test and the Task-Switching Test, were administered to 20 concussed adolescents within 72 h postinjury as well as at 1 wk, 2 wk, 1 month, and 2 months postinjury. Twenty healthy, matched control subjects were similarly assessed at the same time intervals. Data were analyzed by two-way, mixed-effects ANOVA to determine the effect of group and time on the dependent variables.

Results: Compared with control subjects, the concussed group exhibited a significantly greater switch cost on the Task-Switching Test (P = 0.038, mean difference value = 38 ms) and a significantly greater reaction time for the Attentional Network Test conflict effect component (P = 0.015, mean difference value = 34 ms) for up to 2 months after injury.

Conclusions: Concussed adolescents have difficulty recovering executive function after injury and may require extended recuperation time before full recovery is achieved. Evaluations focusing on attention and executive function can be useful additions in the assessment and follow-up after head injury.

Introduction

The Centers for Disease Control and Prevention have described brain injury as a silent epidemic,[20] which suggests that mild traumatic brain injury (mTBI) has become a public health problem, the magnitude and the effect of which are underestimated by current surveillance systems. Many of the mTBI that occur in young adults and adolescents take place in the context of sport activities[19] and thus fall into the category of sports-related concussion. It has been found that deficits from this injury may last longer than those reported by the patient and may be present even after the return to unrestricted activity,[3,27,38] suggesting that current clinical assesment tools may lack sufficient sensitivity to accurately track functional recovery.

Executive function has classically been defined as the capacity to flexibly plan purposeful behavior[21] and is considered to be responsible for the synthesis of external stimuli and preparation for action.[24] Attention processes are believed to be important elements of executive function[1] as well as tasks requiring deliberate attention including decision making, troubleshooting, novel sequence of action, and tasks considered technically difficult.[31] These functions can be tested by using a variety of laboratory-based tasks in which an individual must generate one of two or more responses in a context-dependent manner. Performance on such tasks has been shown to be deficient in college age students who have suffered a concussion for up to 1 month after injury.[15] Previous literature suggests that tests that focus on executive function in individuals recovering from mild to moderate TBI may be useful in predicting outcome from injury.[16]

Although the adolescent brain has not yet reached full maturation[8,23,32] and is in a period of rapid development from approximately 14–16 yr old,[1,13] few studies have focused on the long-term consequences of concussion in adolescents. In a retrospective study assessing sport concussions in children, adolescents, and adults, Baillargeon et al.[2] reported that adolescents displayed persistent neurophysiological deficits that were present at least 6 months after a concussion and were more sensitive to the consequences of concussion than that in adults. The adolescent age group has been reported to be vulnerable to the effects of concussion due to the continued development of the frontal region of the brain,[22] which is responsible for working memory and executive function. A head injury during this critical development time could result in deleterious effects on these cognitive components.[2] Because executive function is considered to encompass the highest levels of human functioning[9] and attention processes are considered to play important roles in the control of action,[31] the monitoring of these cognitive elements in a population particularly vulnerable to the effects of concussion is warranted.

Recognizing how such cognitive functions are affected by and recover after concussion in adolescents can help medical personnel better identify incomplete recovery, which is a predictor of recurrence of brain injury,[14] and provide much needed additional data for the reintegration to preinjury levels of mental and physical activities. Therefore, the purpose of this study was to prospectively and longitudinally examine measures of attention and executive function in concussed adolescents and healthy, matched control subjects within a 72-h acute postinjury interval and for the subsequent 2 months postinjury.

The hypothesis of this investigation, based on prior research in young adults, was that adolescents would be significantly affected by concussion on tests of attention and executive function for up to 1 month postinjury when compared with a healthy group of age-matched control subjects who underwent the same testing timeline and protocol.

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