Repeated measures of cognitive processing efficiency in adolescent athletes: implications for monitoring recovery from concussion.

OBJECTIVE: The objective of this study was to determine whether an adolescent athlete, in the absence of concussion, would be expected to show an improvement in cognitive function during the course of a high school football season.
BACKGROUND: At least 60,000 American high school football players suffer cerebral concussion every year, and symptoms may persist for 4 or more years in as many as 24%.
METHOD: 34 members of a cohort of healthy athletes, aged 13-18, were administered a computerized neuropsychologic test battery from the Automated Neuropsychological Assessment Metrics (ANAM) before and after the 1997 high school football season, with a mean interval of 16.1 (range 12.3-20.4) weeks between tests. Preseason and postseason scores on eight tests were compared, with significance determined by paired t-test. For those tests in which an improvement was noted, one-way analysis of variance and Wilcoxon tests were used with both preseason and postseason data to determine if there was a measurable difference in cognitive processing efficiency between older and younger subjects.
RESULTS: Improvements in processing efficiency (p < 0.001) were noted on tests designed to measure visual scanning and sustained attention (CDS), immediate recall (CDI), and short-term memory (CDD). Older subjects generally performed better on each of these tests, though the difference was significant in only one case (postseason CDI, 17-18 year olds vs. 13-14 year olds, Wilcoxon, p = 0.043).
CONCLUSIONS: Our findings suggest that ANAM is sensitive to differences and improvements in cognitive function during a 4 month interval in adolescence. They also suggest that using "return to baseline" cognitive function as the criterion for evidence of recovery from concussion may be insufficient, especially when the baseline measurement was obtained 4 or more months prior to the date of "full recovery."