Concussion is common. For example, it accounts for over 5% of all sporting injuries in American high-school sport (1). Return to play or training before recovery from concussion can result in serious and long-term neurological injury to the athlete (2,3,4).
There are few treatments for concussion other than rest, so the goal of any concussion management system should be to prevent the athlete returning to sport (training or play) before their brain has recovered (2,5).
Evidence-based concussion management guidelines, agreed upon at the First International Conference on Concussion in Sport (2) are clear: "appropriate management of concussion requires individual assessment incorporating objective neuropsychological testing".
The most appropriate and sensitive way to use neuropsychological tests is to conduct yearly baseline (ideally pre-season) testing of all individuals participating in contact sport (Collie et al. 2001, 6). This allows comparison of any after-injury test to the individual's own baseline.
Almost all neuropsychological tests (whether administered on a computer or by paper and pencil) have both practical and technical limitations that make them unsuitable for use by a non-specialist medical practitioner (Collie et al. 2001, Collie & Maruff 2003, Collie et al. 2003d). This is not the case with CogState Sport, which is designed for use by non-specialists. CogState Sport may be administered by people with minimal training. Reports must be interpreted by a physician, but in most cases that physician does not need to have neuropsychological expertise (Collie & Maruff 2003).
In some cases CogState Sport does recommend that reports are interpreted by a neuropsychologist. This is when an athlete's test scores consistently fall outside the age, sex, and education-matched normative range.
Validation of CogState Sport
Collie et al. 2001 have discussed how paper and pencil neuropsychological tests have limitations in being applied to monitoring recovery from concussion. Computerized tests can overcome these, but care must be taken to make them practical to use. In relation to the construct validity of CogState tasks, Collie et al. 2001a reported how the CogState detection and identification tasks are reliable and well correlated to the DSST and trail-making test B, two tests widely used in the monitoring of recovery from concussion.
However the CogState tasks are more sensitive to the cognitive effects of sporting concussions (Makdissi et al. 2001, Makdissi et al. 2004). Collie et al. 2003 have also shown that for the four CogState speed task outcomes they reported the intraclass correlations after one week ranged between 0.69 and 0.82. Furthermore, Collie et al 2003a have shown that computerization of paper and pencil neuropsychological tests does not necessarily improve their sensitivity or reliability. Comparing CogState Sport with another computerized cognitive test used for concussion management, Broderick et al. 2004 report that the CogState and ImPACT test batteries are both able to identify correctly subjects given alcohol rather than placebo. However, the CogState detection task is particularly sensitive on its own.
Note that there is an important distinction between sensitivity to change in individuals (answers the question "is this person impaired compared to how he/she is normally?") and sensitivity to change in groups (answers the question "which group of athletes is the impaired group and which is the unimpaired group?"). To be useful in concussion management, a test must be sensitive to changes in individuals (Collie & Maruff 2003, Collie et al. 2004).
In a review, Collie et al. 2003d explained how care is needed in interpreting changes in scores for serially-administered neuropsychological tests. Collie et al. 2003d added to the statistical methodology discussion by pointing out that reliable change analyses should assess changes in an individual's test score relative to a control group assessed at similar time-points. Previously described reliable-change calculations did not do so, even though the necessary data was available.
Collie & Maruff 2003 have argued that team doctors are usually a more appropriate choice than neuropsychologists to interpret the results of computerized neuropsychological testing, provided these tests give a "cognitive-change from baseline" vs. "no cognitive-change from baseline" outcome.
McCrory et al. 2004 found that performance in CogState Sport/CogState tasks improves between the ages of 9 and 15, after which there is little further change up to age 25, and this must be taken into account in managing concussion of children below age 15.
Finally, the CogState tasks used in the CogState Sport test battery have been validated in many conditions other than concussion, including alcohol, fatigue and benzodiazepines, and 15 other conditions / indications / interventions.
Research findings
Some key findings from research in various sports, using CogState Sport:
- Makdissi et al. 2005 have reported the outcomes when CogState Sport was incorporated into the Concussion Management system of professional Australian Rules Football. They found that 92% of injuries led to return to play within 1 week (no games missed), and that the injury rate in the first game back for previously concussed players did not differ significantly from that for matched control players.
- Moriarity et al. 2004, studied an amateur boxing tournament. They found that with the exception of boxers whose contest was stopped by the referee, amateur boxers participating in multiple bouts during the 7-day tournament showed no evidence of cognitive dysfunction in the immediate postbout period.
- Straume-Naesheim et al. 2005 investigated whether Norwegian professional soccer players suffered measurable cognitive detriment correlated with self-reported lifetime concussions and with exposure to heading the soccer ball. No such correlation was found.
References
- Powell JW & Barber-Foss KD. Traumatic brain injury in high-school athletes. Journal of the American Medical Association 1999; 282: 989-91.
- Aubry M, Cantu R, Dvorak J, et al. Summary and agreement statement of the First International Conference on Concussion in Sport, Vienna 2001. Recommendations for the improvement of safety and health of athletes who may suffer concussive injuries. Br J Sports Med 2002;36(1):6-10 45.
- Cantu RC. Second Impact Syndrome. Clinics in Sports Medicine 1998; 17: 37 -44.
- Cantu RC. Recurrent head injury in sport: Risks and when to retire. Clinical Journal of Sports Medicine 2003; 22: 593-603.
- McCrory PR. Were you knocked out? A team physician's approach to initial concussion management. Medicine and Science in Sports and Exercise 1997; 29: S207-212.
- Echemendia RJ, Cantu RC. Return to play following sports-related mild traumatic brain injury: the role for neuropsychology. Appl Neuropsychol 2003;10(1):48-55.
