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

Results

The concussion subjects were tested within 3 d of injury (mean ± SD = 2.15 ± 0.75 d). After the initial testing took place, each participant returned for testing in the following increments: 8 ± 1.8, 17 ± 3.6, 30 ± 2.6, and 59 ± 3.5 d after injury. Control subjects began participation during the same sport season as their matched concussed subject. After the initial testing session the control subjects returned for testing in the following time increments: 8 ± 2.1, 16 ± 4.5, 30 ± 3.7, and 57 ± 6.4 d after the initial testing session. No significant demographic group differences were observed between the concussion and the control group (Table 1). In one case, a direct sport match was not obtained. The evaluation of clinical symptoms between the concussed and control group revealed a significant time by group interaction (P < 0.001). Follow-up pairwise comparisons revealed that concussed subjects exhibited a significantly higher symptom score than controls at the following time points (mean ± SD): 72 h (concussion = 43.0 ± 25.1, control = 4.3 ± 4.2; P < 0.001), 1 wk (concussion = 30.8 ± 25.2, control = 2.5 ± 2.7; P < 0.001), and 2 wk (concussion = 24.1 ± 22.1, control = 4.1 ± 8.9; P = 0.001). Those differences were no longer statistically significant at the 1-month (concussion = 12.6 ± 14.3, control = 3.1 ± 4.5; P = 0.010) or 2-month (concussion = 11.3 ± 19.8, control = 4.2 ± 6.3; P = 0.149) time points, indicating symptom resolution for concussed subjects on average between the 2-wk and 1-month testing period.

The evaluation of the alerting effect of the ANT demonstrated no significant differences between groups or testing days, and no interactions were present (Fig. 3A; interaction effect P = 0.516, main effect of group P = 0.323, main effect of time P = 0.223). Similarly, the evaluation of the orienting effect of the ANT revealed no differences between groups or testing days, and no interactions were present (Fig. 3B; interaction effect P = 0.258, main effect of group P = 0.236, main effect of time P = 0.266). The analysis of the ANT conflict effect revealed a significant main effect of group (P = 0.015, effect size = 0.192, mean difference value = 34 ms), with the concussed group showing a significantly greater RT difference than controls, indicating a greater conflict effect. A main effect of time was also found to be significant (P < 0.001; Fig. 3C), but with no significant interaction between group and time (P = 0.308). Similar to the conflict effect, the TST switch cost (RT difference) was greater for the concussed group (P = 0.038, effect size = 0.125, mean difference value = 38 ms). A main effect of time (P < 0.001; Fig. 4) was also found to be significant, but with no significant interaction between group and time (P = 0.253).

Figure 3.

Mean + SE for performance on the ANT across the 2-month testing period: alerting effect (A), orienting effect (B), and conflict effect (C). The main effects of group and time were observed for the conflict effect, whereas no significant main effects or interactions were found for the alerting or orienting effects.

Figure 4.

Mean +SE for the switch cost, the evaluation of executive function by the TST. The mean RT difference between a switch trial and a no-switch trial for individuals with concussions and controls across the 2-month period of testing is displayed. Main effects of group and time were observed for this measurement.

Observation of the recovery curves for the conflict effect and switch cost data revealed improving scores for the first 2 wk of testing for the control subjects, suggesting a practice/learning effect on these measures (Figs. 3C and 4. Similarly shaped recovery curves were evident for the concussed subjects for the same period; however, their scores remained significantly different from the controls throughout the testing period.

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