Australasian Science: Australia's authority on science since 1938

The Head Coach

By Tim Hannan

New guidelines aim to reduce the risk of cognitive impairment from concussion in sport.

Concussion is a common occurrence in contact sports, with both the AFL and NRL calculating that about six players from every elite club suffer a concussion each season. Estimates for lower competitions have produced similar or slightly lower frequencies.

New international guidelines on the management of concussion in sport aim to reduce the risk of short- and long-term cognitive impairment by advocating “best practice” guidelines on the identification and management of concussive symptoms. Published last March, the Consensus Statement of the 4th International Conference on Concussion in Sport will also focus the attention of researchers on key unanswered questions in the field.

Concussion is a disruption of brain function that results from a blow to the head, either through a direct strike or the indirect effect of impact elsewhere on the body being transmitted to the head. It is a mild form of traumatic brain injury in which the observed symptoms are presumed to largely result from a disturbance of brain function rather than as a result of structural damage.

The symptoms of concussion include headache, dizziness, blurred vision and nausea, along with cognitive difficulties such as confusion, disorientation and amnesia for events occurring in a period preceding the injury. These features are usually immediately apparent, but in some cases they may emerge or evolve over a period of hours or days. While the majority of concussions resolve within a week or so, around 10–20% of athletes experience lingering cognitive and physical symptoms.

Traditionally, the significance of concussion was minimised by players and coaches alike: the injury was a “head knock” that should be “played through”, and the only reason to bench a player was impaired sporting performance. A decade ago, when the Canadian ice hockey star Eric Lindros followed independent medical advice to sit out games until his symptoms resolved, this “unmanly” behaviour lost him the team captaincy, and spectators threw babies’ dummies onto the ice when he returned.

More recently, researchers and retired athletes have promoted an evidence-based understanding of the risk of prolonging concussion symptoms by returning to play, and of the risk of longer-term consequences of repeated concussions. Recognising the need to protect the welfare of players, the major football codes and many other sporting organisations have adopted concussion management guidelines – largely consistent with international practice – including policies on sideline assessment of suspected concussion, immediate removal from play, subsequent medical and neuropsychological evaluations, and a graduated return to play protocol.

Strategies to reduce the risk of concussion have also been implemented, such as rule changes and the prescription of protective equipment in younger age competitions. Bio­mechanical studies have found that head gear and helmets reduce the impact force of a collision on the brain, although research has yet to demonstrate a reduction in the incidence of concussion. It has been speculated that, at the elite level, protective equipment may encourage players to take greater risks.

Despite this progress in research and practice, some questions are yet to be satisfactorily answered. One concerns the long-term effects of multiple concussions. It is widely hypothesised that multiple concussions or subconcussive injuries can result in the condition known formerly as dementia pugilistica and now as chronic traumatic encephalopathy (CTE), a progressive neuro­degenerative disease associated with the build-up of the tau protein in the brain. However, the lack of epidemiological, cohort or prospective studies leaves any association between repeated concussion and CTE unproven. Some elite athletes are at risk of CTE, but the factors that predict this are as yet unclear.

A second question concerns the lack of evidence for the widespread belief that individuals appear to vary in their risk of suffering a concussion, or in the magnitude or duration of subsequent effects. One line of research has explored the occurrence of the Apolipoprotein E protein (ApoE) allele, which has been associated with increased incidence of several neurological conditions, including traumatic brain injury, and with the degree of impairment in experienced professional boxers. However, studies have yet to find that ApoE confers an increased risk for concussion.

The third issue is the holy grail of sports neuropsychologists: an effective intervention to reduce the severity and duration of concussive symptoms. To date, the absence of evidence for any therapeutic interventions means that the only advice given to athletes is to refrain from physical and cognitive activities, with a gradual return to exercise over several days.

Tim Hannan is an Associate Professor of Clinical Psychology at Charles Sturt University, and the President of the Australian Psychological Society.