Cognition In The Days Following Concussion

Abstract

PURPOSE While it is recognised that neuropsychological testing is an important part of the post-concussion medical evaluation, the 'golden rule' of concussion management remains the recommendation that athletes must not be returned to play whilesymptomatic (Concussion in Sport Group, Vienna, 2001). This study sought to compare post-concussion cognitive function in symptomatic and asymptomatic athletes. METHODS A total of 848 pre-season CogSport™ tests were collected prospectively in 615 individual Australian Rules (ARF) footballers between 2001 and 2003. Sixty-one footballers were concussed, and received follow-up clinical and cognitive evaluation within 7 days of injury. Footballers were classified as either symptomatic (SYMP) or asymptomatic (ASYMP) on the basis of the post-concussion clinical evaluation. RESULTS As a group (N=61), concussed footballers displayed significant dysfunction on tests of simple, choice and complex reaction time, and divided attention, compared to their own baseline performance. There were no age differences between SYMP (N=28; 22.6 ± 3.8yrs) and ASYMP (N=33; 23.2 ± 3.8yrs) groups, however SYMP footballers were tested closer to the injury (1.9 ± 1.2days) than ASYMP footballers (3.2 ± 1.7days). At the time of testing, SYMP footballers reported 1.8 ± 1.0 symptoms (range 1–4). Group by assessment (baseline vs post-injury) ANOVA revealed that SYMP footballers displayed greater dysfunction than ASYMP footballers on tests of simple, choice and complex reaction time. Both groups were impaired relative to baseline on tests of divided attention. The magnitude of post-injury dysfunction in symptomatic footballers was large according to conventional statistical criteria (d' range: 0.55–1.02). No changes were observed on tests of working memory or new learning after concussion. CONCLUSIONS Symptomatic athletes display large and significant post-concussion dysfunction on tests of motor function, simple and divided attention. These changes are greater than those observed in asymptomatic athletes, who display only mild deficits in attention. These findings support current recommendations that athletes must not be returned to play while symptomatic. Consistent with prior research, tests of simple cognitive processes appear more sensitive to concussion than tests of more complex cognition.