Robust RT deficits were observed acutely following concussion .
Minimal magnitude differences were noted when comparing between- and within-subject effects , suggesting that pre-injury baselines may not add clinical value in determining post-injury RT impairment .
RT deficits persisted up till the intermediate-term ( 21–59 days post-injury ) timeframe and indicate lingering deficits exist .
Mean effect size differences were observed between RT measure types and computerized neurocognitive testing platforms ; however , all categories displayed negative effects consistent with impaired RT following concussion .
Reaction time ( RT ) deficits are reported following concussion , but it is unknown when these deficits normalize to pre-injury status .
It is also unclear how factors such as RT measurement technique and participant characteristics influence post-concussion RT .
The purpose of this systematic review and meta- analysis was to ( 1 ) characterize acute post-concussion ( 0–3 days ) RT impairments , ( 2 ) examine RT recovery over time , and ( 3 ) explore moderating factors related to acute RT impairment following concussion .
Cognition in the days following concussion: comparison of symptomatic versus asymptomatic athletes.
BACKGROUND Concussion is a common neurological injury occurring during contact sport . Current guidelines recommend that no athlete should return to play while symptomatic or displaying cognitive dysfunction . This study compared post-concussion cognitive function in recently concussed athletes who were symptomatic/asymptomatic at the time of assessment with that of non-injured ( control ) athletes . METHODS Prospect i ve study of 615 male Australian Rules footballers . Before the season , all participants ( while healthy ) completed a battery of baseline computerised ( CogSport ) and paper and pencil cognitive tasks .  Sixty one injured athletes ( symptomatic = 25 and asymptomatic = 36 ) were reassessed within 11 days of being concussed ; 84 controls were also reassessed . The serial cognitive function of the three groups was compared using analysis of variance . RESULTS The performance of the symptomatic group declined at the post-concussion assessment on computerised tests of simple , choice , and complex reaction times compared with the asymptomatic and control groups . The magnitude of changes was large according to conventional statistical criteria . On paper and pencil tests , the symptomatic group displayed no change at re assessment , whereas large improvements were seen in the other two groups . CONCLUSION Injured athletes experiencing symptoms of concussion displayed impaired motor function and attention , although their learning and memory were preserved . These athletes displayed no change in performance on paper and pencil tests in contrast with the improvement observed in asymptomatic and non-injured athletes . Athletes experiencing symptoms of concussion should be withheld from training and competition until both symptoms and cognitive dysfunction have resolved
Robust RT deficits were observed acutely following concussion .
Minimal magnitude differences were noted when comparing between- and within-subject effects , suggesting that pre-injury baselines may not add clinical value in determining post-injury RT impairment .
RT deficits persisted up till the intermediate-term ( 21–59 days post-injury ) timeframe and indicate lingering deficits exist .
Mean effect size differences were observed between RT measure types and computerized neurocognitive testing platforms ; however , all categories displayed negative effects consistent with impaired RT following concussion .
Reaction time ( RT ) deficits are reported following concussion , but it is unknown when these deficits normalize to pre-injury status .
It is also unclear how factors such as RT measurement technique and participant characteristics influence post-concussion RT .
The purpose of this systematic review and meta- analysis was to ( 1 ) characterize acute post-concussion ( 0–3 days ) RT impairments , ( 2 ) examine RT recovery over time , and ( 3 ) explore moderating factors related to acute RT impairment following concussion .