Menu Close

The Daniel Bell effect: sports injuries and the brain explained

Former AFL player Daniel Bell is seeking compensation for brain damage linked to multiple concussions. AAP

What happens to the brain in a collision?

A blow to the head can cause any form of damage to the brain. On the serious side, it can cause a large haemorrhage and damage to a large amount of brain tissue.

But the most common injury after concussion is quite small - a minor amount of bruising, limited damage to brain tissue, and some swelling. You can usually recover very quickly.

How long does recovery take?

Normally after the person regains consciousness the brain moves back to near-normal functioning.

But if you conduct subtle neurological testing, you find that the person remains impaired after an episode of concussion for quite some time. Depending on the severity of the blow, this impairment can last for hours, days or even weeks.

We don’t know the underlying nerve cell explanation for the varying rates of recovery. It’s not just related to swelling and bruising.

What we do know is that a person’s ability to recall information, to process information, and to rapidly solve a problem, can be impaired for varying lengths of time after a concussion.

What are the long-term effects of multiple concussions?

Repeated episodes of concussion can have an additive effect. So if you’re concussed several times or several dozen times you’re more likely to develop long-term consequences than if you’ve only had one or two episodes of concussion.

How do the impacts of head trauma manifest over time?

I think we can see that most easily in boxers, where repeated head injuries or head trauma from boxing can lead to a form of dementia. We’ve even given it a name – it’s called boxers dementia or dementia pugilistica.

But even more worryingly, people who have been knocked unconscious are actually more likely to develop Alzheimer’s disease, even decades later.

We’ve only got to look at the pictures of Mohammad Ali to see a person who has had not only slowing of his cognitive functions but also motor consequences of repeated brain injury – he’s developed a form of Parkinson’s as a result of his professional sport.

How widespread is head trauma in sport?

We don’t know how widespread reduced cognitive function is in professional sport because we’ve never taken it seriously enough.

As far as coaches and trainers, if a person wakes up after being knocked unconscious and can stand on their feet and can count backwards from ten, they’re back on the field.

That’s not necessarily the best approach and I think we need to focus on the science a little better.

We’ve taken things like knee injury very seriously for a long period of time. It’s now time to start looking at the consequences, and responses to, brain injury.

How should we respond to brain injury?

The first thing is to find out whether the person is still impaired from the episode. You can use things like computerised cognitive testing batteries.

CogState is one device that has been developed in Melbourne in conjunction with the University of Melbourne, which measures cognitive function in people with memory problems. It can also be used in a modified form to test how impaired a person is after an episode of concussion.

This type of testing could be done at the side of the field to find out if a person is ready to go back out during the game. Or it can be done to later to find out whether they’re ready to return a week or two weeks later.

CogState is already being used in Gridiron leagues in the US and potentially by one Melbourne football Club. There is also another company that has a large share of the computerised testing after sports injuries.

Computerised cognitive testing could almost be mandated in professional sports. Just like you can’t get back behind the wheel after a serious illness until the doctor gives you permission - a professional sports person should be required to show they are fit to continue playing with a test such as this.

How can players reduce the risk of injury?

There’s two things we can do to reduce the risks.

Firstly, make sure people don’t suffer a blow to the head that’s sufficient enough to concuss. That can really only be done by changing the rules of the sport.

Secondly, we can reduce the effect of a blow to the head using things like helmets, in selected groups.

I don’t want to suggest what should be done to the AFL but there should be a strong obligation for players to wear helmets after they have sustained two or three concussions.

Helmet use could be mandated after several episodes of concussion to protect players from long-term brain injury.

What occurs in our brain that causes us to forget things?

People have trouble with memory when their brain call connections are damaged. These connections are called synapses.

If we can’t attend to information, we can’t lay down a memory.

The second step is consolidation of that information into the storage part of the brain, and that’s largely centred on the hippocampus and the temporal regions of the brain.

Thirdly, we need to access that memory later. That comes back to the frontal regions of the brain – they’re important to allow us to get back into those memory banks and recall a piece of information.

So there are three processes – attention, consolidation of a memory, and then accessing that memory later on, and they require different neural structures.

The common abnormality that can affect all those processes is loss of brain connections: loss of synapses.

That leads to what causes the loss of synapses. That can be due to a number of things: head injury, poor vascular supply such as stroke, damage from neurodegenerative conditions such as dementia.

There are many different processes that can affect the memory sequences.

When do these memory lapses become serious?

If you are having problems with memory after a number of concussions, the first step is to assess how much brain function has been lost.

There is an argument that all elite sports players should have cognitive testing before they even go onto the field, so we’ve got a base line from which we can compare any cognitive decline.

When a player is concussed, we can say ‘before you started the game you scored X, now you’ve clearly come down. Even though you may be functioning at a higher level that others, you’ve still come down from your baseline.‘

Want to write?

Write an article and join a growing community of more than 174,400 academics and researchers from 4,802 institutions.

Register now