Concussion-related deficits in the general population predict impairments in varsity footballers



We investigated the long-term cognitive effects of concussion in 19,261 members of the general population and a cohort of varsity American football players with a history of frequent head impacts, using tests that are known to be sensitive to small changes in performance.


We asked 19,261 participants to complete a demographic questionnaire and 12 cognitive tests measuring aspects of executive function, including inhibitory control. We compared the performance of those reporting a history of concussion (post-concussion) to those reporting no history of concussion (non-concussed) on the cognitive battery and four non-cognitive variables. We used the results of this population-level study to predict the profile of cognitive performance in varsity American football players, who completed the same cognitive tasks.


Post-concussion and non-concussed participants did not differ on 11 of the 12 cognitive tasks employed. However, on a test of inhibitory control based on the classic Stroop paradigm, post-concussion participants showed accuracy-related impairments specific to the incongruent conditions of the task. Post-concussion participants reported higher levels of anxiety, depression, and trouble concentrating. An entirely independent sample of 74 varsity American football players demonstrated the same pattern of impairment: compared to healthy controls, they scored significantly lower on the test of inhibitory control but were indistinguishable from controls on the 11 other tasks.


Self-reported concussion is not associated with long-term general effects on cognitive function. Nevertheless, those who report at least one concussion and those who expose themselves to long-term frequent sport-related head impacts do have a modest, but statistically robust, deficit of inhibitory control.

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We thank the Canada Excellence Research Chairs (CERC) program, which generously supported the research reported here (grant #215063 awarded to AMO).

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Correspondence to Clara Alexandra Stafford.

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Conflicts of interest

AMO is a Fellow of CIFAR and co-Director of the Azrieli Program in Brain, Mind, and Consciousness. Some of the cognitive tests used in these two studies are marketed by Cambridge Brain Sciences Inc., of which Dr. Owen is the unpaid Chief Scientific Officer. Under the terms of the existing licensing agreement, Dr. Owen and his collaborators are free to use the platform at no cost for their scientific studies and such research projects neither contribute to, nor are influenced by, the activities of the company. As such, there is no overlap between the current study and the activities of Cambridge Brain Sciences Inc., nor was there any cost to the authors, funding bodies or participants who were involved in the study.

Ethical statement

This study was approved by the Health Sciences Research Ethics Board of the University of Western Ontario. All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

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Stafford, C.A., Stojanoski, B., Wild, C.J. et al. Concussion-related deficits in the general population predict impairments in varsity footballers. J Neurol 267, 1970–1979 (2020).

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  • Concussion
  • Neuropsychology
  • High-response rate survey
  • Inhibitory control
  • Varsity football