This week I had the opportunity to ask Dr. David Darby, Chief Medical Officer of CogState, for his views on the hot topic of concussions in school sports. Several states are in the process of enacting legislation that call for formal evaluation of an athlete’s cognitive health after a concussion on the playing field. The main purpose behind this kind of legislation is to reduce the chances of long term brain injuries in student athletes. Below is an update on sports concussion management:
1. Dr. Darby, concussions in school team sports have received substantial attention in the media and public policy settings in the past few years. Some reports focus on more aggressive play in school sports, while others point to heightened awareness by parents on the potential dangers of their child being exposed to multiple hits over the course of a season. Can you comment on the factors you are seeing in the school sports world for better concussion management?
The understanding of concussion remains poor among the general population, including schools.
Certainly there are several organizations working to increase awareness of the injury. Education is the key initiative required to both improve awareness of the features, consequences and management of concussion at all levels, including athletes, parents, coaches, trainers, teachers and doctors.
In parallel with educational efforts, having pre-season assessments of athletes to document their normal performance and detect medical conditions that might affect their risk for concussion and their routine medical assessment after concussion is critical if doctors are to be able to manage athletes safe return to play and activities. Pre-season assessments should include a Baseline computerized cognitive assessment since it is not possible to be sure of an athlete’s pre-concussion performance once they have been injured.
Cooperation at all levels (parents, coaches, athletic trainers, doctors) is critical for athletes to be managed properly with such programs encompassing pre-participation and post-injury aspects. Jon Almquist at Fairfax County Public Schools runs an integrated concussion management program. Another example of a school moving in this direction is Cedar Ridge in Round Rock, Texas.
2. How does Axon Sports provide cognitive testing for sports concussions?
The Axon Sports Computerized Cognitive Assessment Tool (CCAT) is one of the tools used by doctors to assess and manage individual recovery of thinking and memory performance after a concussion. It is an 8-10 minute test available online from Axon Sports, and is usable anywhere there is a connection to the internet in standard web browsers. There is also a free preview of the test available at the Axon web site which we encourage all athletes to try out.
Axon Sports is a joint venture with CogState Ltd, a publicly traded Australian technology company, and Quixote Investment, a Portland, Ore.-based investment group. The joint venture is based in Wisconsin where it is centrally located to service North America.
The technology behind the Axon Sports Computerized Cognitive Assessment Tool (CCAT) was conceived in 2000 by CogState to help medical providers measure the cognitive function of Athletes after suspected concussions or Traumatic Brain Injuries (TBI). Athletes establish Baseline or “snapshots” of their brains’ speed and accuracy using the CCAT’s four simple tasks.
After Injury testing with the Axon Sports CCAT is at the discretion of the athlete’s doctor since there are many other aspects to consider medically after a concussion. It is usually performed after symptoms have resolved since the effects of concussion on thinking and memory usually linger beyond the symptoms for several days and hence suggest that the athlete’s brain function is still not back to normal.
The CCAT compares After Injury performance with the individual athlete’s Baseline performance to determine whether there is a significant decline still. Due to the lack of practice effects in the Axon Sports CCAT, it can then be used repeatedly to document recovery of the athlete’s cognitive performance back to their Baseline, which in over 80% of athletes will occur within 7-10 days. Thereafter, a graduated individualized return to activity and play program will usually be recommended by the athlete’s doctor.
3. Why is it so important for a baseline cognitive test to occur each year or playing season?
Baseline Testing, together with a pre-season evaluation, is an essential part of the concussion management process. The brain matures at a rapid pace in children and adolescents. These changes improve both speed and accuracy, which are the main parameters measured in the Axon Sports CCAT. These improvements occur to at least 15 years of age in prior studies, but may continue in some athletes to age 18 years. Repeating the Baseline annually can help reset the Baseline for a maturing athlete to more accurately reflect their true pre-season abilities.
In addition, athletes may injure themselves in non-supervised sporting or recreational activities between school sporting seasons. Some of these injuries may be concussions and may not be reported to school teachers or sport supervisors. Having an annual Baseline test will detect deteriorations in Baseline abilities that otherwise might not be suspected by the athletes, parents, school staff or their medical practitioners.
4. What are the risks for student athletes returning to the playing field after a concussion, and how does post-concussion cognitive testing provide information to coaches, physicians, students, and parents?
By definition, a concussion is associated with disturbances of function of the athlete’s brain. These changes are thought to be transient, which means they do recover, though sometimes recovery may be prolonged beyond the usual seven to 10 days. It is a well-accepted medical principle that recovery after injury should be allowed to occur, and this principle applies equally for the injured brain. Evidence of ongoing injury after a concussion includes persistent symptoms (e.g. headache, dizziness, fatigue etc), balance disturbance, and cognitive dysfunction. Uncomplicated concussions do not show changes in routine neuroimaging studies such as computerized axial tomography (CAT) or magnetic resonance imaging (MRI).
However, “a concussion” may be complicated by bruising (called contusion) of the brain or more severe hemorrhages, swelling or many other rare complications. These will be evident to health practitioners by unusual features (such as finding asymmetrical responses to reflex testing), an unexpected deterioration in symptoms, or imaging abnormalities. Clearly careful supervision of concussed athletes is important to detect such complications.
Given that there are no such unusual complications of a concussion; the main risk is exposing the injured brain to further injury before it is recovered. There are currently no gold standards to allow medical practitioners to easily determine full recovery, but the CCAT seems to be one of the most sensitive measures available at the moment so is a useful tool for the doctor to use in assessing recovery.
When there is a baseline test result available, a doctor can compare results to help indicate whether the brain has fully recovered. Concussion causes subtle changes in the speed and accuracy of cognition (thinking). These changes are usually the last symptoms to go away after a concussion and they can be very slight. In fact, it is very difficult to detect them without a computerized test which compares an individual to themselves when they were “normal.” This means that Baseline testing in the pre-season, before any injury occurs is essential.
If an athlete returns to play or activity before recovery from a brain injury, they may experience persistent or prolonged symptoms and cognitive impairment. In addition, we risk exposing the athlete to further collisions or injury if they are not as alert or reactive as usual. Whether athletes with incompletely recovered concussion injuries are more at risk of catastrophic brain swelling after further head injury (a condition known medically as Second Impact Syndrome or SIS) is controversial. This is in part because SIS seems to be very rare indeed, and can occur in children or adolescents who may not have had a first concussion and may be confused with other causes of collapse after head injury (particularly hemorrhages in or around the brain). There are also suggestions that SIS may occur in particular genetically susceptible individuals only.
The concise and clear information obtained from the results of a CCAT test is therefore very helpful for doctors managing an athlete’s individualized recovery assessment since it is one of the most sensitive means for determining whether the brain is still showing impairment in comparison to their own Baseline performance. Coaches, students and parents can therefore benefit by understanding whether or not the athlete’s brain needs further rest and can monitor the recovery process.
5. The typical definition of a mild Traumatic Brain Injury (mTBI) is loss of consciousness for up to 30 minutes and post-trauma amnesia for up to 24 hours. Is there any overlap between more severe concussions and mTBI?
Such definitions of mTBI emphasize the importance of assessment of an athlete who has suffered a significant head injury by an informed health practitioner. Clearly if there are features that are unusually prolonged or atypical for an uncomplicated concussion injury, the athlete should be managed appropriately. This may include stabilization of the athlete at the field, ambulance and paramedical evaluation and hospital assessment.
The role of the Axon Sports CCAT in such injuries is minor around the time of initial assessment, but can certainly be useful for comparison later in their recovery to a Baseline CCAT assessment.
6. The professional sports world has seen the tragic deaths of active and retired players who exhibited signs of the degenerative brain condition chronic traumatic encephalopathy (CTE). Bob Probert, a well known National Hockey League player, and Dave Duerson, a former NFL player for the Chicago Bears are recent examples of professional sports players who died fairly young after careers in heavy contact sports. How strong is the connection between CTE and successive concussions sustained by some professional athletes? Also, any thoughts on research avenues for further exploring CTE in the collegiate and pro sports world?
This is currently an area of active research but, in my opinion, it remains premature to make firm conclusions about the relationship between repeated exposure of these athletes to concussive (or subconcussive) injuries during their careers and the neuropathological changes found by Dr McKee and colleagues. Further research is required. In particular, research and follow-up is required in the modern era in which players are assessed more extensively than before, along with the changing culture of football to both report concussions and conform to recommended management guidelines.
It is my speculation that future research in human concussion will focus on subconcussive injuries. These may be milder forms of concussion and more common than is currently suspected (as suggested by recent studies at Purdue University). Defining the full spectrum of injury is required before techniques that reliably detect the effects of concussive injuries can be delineated, and studies of true incidence, precipitating factors and outcomes can be evaluated. Only then can cost-effective diagnostic techniques and therapies, both preventative and therapeutic be rationally evaluated and recommended.
7. Do you think we will find that personal genetics plays a role in the susceptibility (or resiliency) to concussions?
Yes. This is clearly a complex area. One example is the reported vulnerability of people with a calcium channel gene mutation (Kors et al Ann Neurol 2001) who are predisposed to both familial hemiplegic migraine and delayed cerebral swelling (edema) and fatal coma after minor head trauma. These may well be the athletes who are truly susceptible to second impact syndrome (even after only one injury). There are also research findings suggesting that certain cholesterol carrying protein gene types (apolipoprotein E4) may be more vulnerable to head injury due to more extensive post-injury brain inflammation and reactive changes.
David Darby graduated from Medicine at the University of Melbourne in 1981, completing a PhD in neurology and neuropsychology in 1990, and his neurology training in 1991. He served as an instructor in Behavioral Neurology at Beth Israel Hospital, Harvard Medical School from 1992 to 1995. He was Chairman of the Memory Disorders Service at the Repatriation Campus of the Austin & Repatriation Medical Centre from 1997 to 2000, where he continues to evaluate patients with cognitive impairment. He also assesses patients at Boxhill Hospital, and in regional Victoria. Prof Darby has published over 70 research papers in international peer-reviewed scientific journals and has co-authored a neuropsychological textbook with Prof Kevin Walsh. He is a Founder and Chief Medical Officer at CogState Ltd developing computerized cognitive testing instruments including for early detection of dementia and concussion in sports, and is also adjunct Associate Professor at the Centre for Neuroscience, and Senior Research Fellow of the Florey Neurosciences Institute, University of Melbourne.