Female footballers and brain injury risk

Is there a link between repeatedly heading footballs and dementia risk?
01 December 2020

Interview with 

Michael Grey, UEA


table football


A question in the collective consciousness recently has been around footballers heading balls, and consequences for their brain health. Last year, Glasgow University published research showing that professional footballers were three-and-a-half times more likely to die from neurodegenerative disease. And now, scientists want to build on this research with a long term study that looks at people’s brains over time. With evidence that women experience more concussion that men in the sporting world, what does this mean for female footballers and the risks associated with heading a ball? Katie Haylor spoke to Michael Grey who's leading this study at UEA...

Michael - So we think that heading a ball causes something called sub-concussive trauma. So if we take concussions, for example, a concussion is a mild traumatic brain injury. It has a number of symptoms like headache, dizziness, feeling like one is in a fog. And that's occurring because of a direct result of damage to the neurons in the brain. A sub-concussive insult occurs because we're getting a bit of a lesser hit that doesn't cause a full-blown concussion, but there is still damage. And the idea is that by heading balls day after day, year after year, the neurodegeneration that builds up in the brain eventually leads to dementia.

Katie - How do you know this? What evidence have we got at the moment?

Michael - The direct evidence will come from animal models. Typically in mice and rats, one can induce a head injury of different kinds. One can look at the behaviour of the animal, and then we look at the brain and we can actually see tau proteins in the brain. We can see amyloid proteins in the brain, and we know that there has been degeneration.

Katie - So these are buildups or plaques that seem to be associated with the degeneration you get in things like Alzheimer's or dementia. Is that right?

Michael - Yes, that's absolutely correct. So when a nerve is damaged, we have a process called Wallerian degeneration. So the nerve dies, it breaks up. And then there are components of the nerve called tau proteins or amyloid proteins that are not soluble. So they actually stick around in the neurons. They adhere to the blood supply, they stop the blood supply and they prevent nerves from functioning and they cause other neurons to die.

Katie - Okay. So there is a pretty decent amount of evidence between the potential long-term effects of heading a football and problems with the brain. But where does the difference in sex come in?

Michael - Yeah. So the difference in sex is we think really important and it has been under studied. I mean, it is a fact that most of the studies of concussion, of sport-related neurodegeneration, they're all done in men. So one of the areas of concern for us is if you look at the statistics of dementia, specifically - in the UK, 61% of the population of people with dementia are women. Now some of that is because women live to a longer age and because it's a disease, obviously, that is more prevalent, the older one gets. That explains some of it, but it doesn't explain all of the difference in that ratio. The other thing that we have to look at is concussions themselves. We know that women experience concussion to a greater extent than do men. And if we put those two things together, it just makes sense that women are more likely to sustain the effects of sport-related neurodegeneration than men. And that's why we really need to study it.

Katie - If you were a betting man, do you have an idea of the mechanisms behind the sex differences? Because I guess there's physicality, but are there sort of hormonal changes that may be involved here? What's going on?

Michael - If you look at the mechanism of injury, you have to think about the brain as some jelly in a bowl. If I smack the side of the bowl, the jelly inside will wobble around. And the nerves that are in that jelly, that is the brain, they are damaged. Now, if we have a much stronger neck, for example, you can actually withstand that bubble of head effect. And therefore there's less wobbling of the brain than if we have weaker muscles. And we know that women are, on average, less muscular than men, particularly in their neck. So that's one area.

And if we look at the physiology, we think that there's an issue with women's cycles. So with the hormonal cycles, we think that women may actually be more at risk of concussion and therefore potentially the effects of neurodegeneration, depending on their cycles.

Katie - How could this inform how sport is done in the future? Because I guess you can't eliminate risk can you? I guess it must be about mitigation.

Michael - No, you're absolutely right. This is all about risk mitigation. We need to understand the risk before we can actually do something about it. And the idea here is it's about exposure to the injury in the first place. So one of the biggest things we can do is reduce exposure to heading the ball. In children for example. Personally, I don't think young children should be heading balls. I think that we can be doing the training in a different way. We can be strengthening the neck muscles, for example, long before we start to head the ball. And we can do things like reducing the amount of heading in practice, increasing the time between practices, where one might head the ball. And I think just by doing that alone, we will be making a difference.


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