Concussion contributes to neurodegenerative diseases

Heads first

Despite all the health benefits that come with exercise and fitness in contact sports, Dr Frances Corrigan would think twice before letting her two young daughters play.

She leads the Head Injury Group at the University of Adelaide, and knows better than most what can happen from a knock to the head.

“You’ve got it in the back of your mind. It’s just being a parent – you’re always a little bit overprotective,” she says. “I’d prefer they get the benefits from sport. But it’s about trying to make sure that it’s safer for everyone participating.”

When abrupt contact is made with the head, the brain moves around in the skull and the nerve fibres, or axons, are stretched.

“Neurons communicate by axons, which are quite long and thin – and don’t like being stretched,” says Corrigan. “You’re changing the environment within the brain, which means that those neurons can’t talk to each other. This is why people become confused, and have subsequent memory problems and sleep problems.”

The healing process, to unstretch the axons, usually takes days or weeks. In some cases, concussion symptoms last significantly longer.

Martha Cantwell knows this firsthand. After playing sport for decades, and suffering at least five concussions, Cantwell was hit in the head while playing Australian football. She wasn’t knocked out, so at first she wasn’t too worried. But over the next few days her symptoms became debilitating.

“Until you experience it, it’s hard to imagine that one knock can change your life so dramatically”

“Until you experience it, it’s hard to imagine that one knock can change your life so dramatically,” she says. “I had headaches, nausea with almost any movement, fatigue, extreme tiredness, brain fog, inability to focus, confusion and memory loss. It was a really scary time.”

She couldn’t drive for six months, or return to her job as a teacher for over a year. Exercise and social activities were completely off the table.

Her experience is not uncommon. Although more men play contact sports, studies have shown that female athletes not only have a higher risk of sustaining a concussion, they take a longer time to recover than men.

Cantwell had a particularly rough time: it was discovered she’d suffered microbleeds, which some studies suggest could lead to worse outcomes for patients. She was told to give the game away, and moved into coaching. She’s now coached at community level and with Collingwood’s AFLW team.

Despite her traumatic experience, she says she’d never discourage someone from playing.

“For me the recovery was too long,” she says. “I lost my identity, my personality, my abilities and my quality of life for a long time, which takes you to pretty dark places.

“I still love sport and am involved with sport, just in a different way.”

Concussion: research shows the risk

The advice to retire from playing was grounded in science: research has shown that repeated concussions increase the risk of memory problems, mild cognitive impairment and potentially Alzheimer’s disease. They also contribute to a condition called chronic traumatic encephalopathy (CTE) – a neurogenerative disease similar to Alzheimer’s disease, which produces tau protein clumps. CTE is believed to be caused by repeated impacts to the head, and is mostly seen in athletes in contact and combat sports.

“For me the recovery was too long. I lost my identity, my personality, my abilities and my quality of life for a long time,which takes you to pretty dark places”

The Australian Sports Brain Bank recently found that almost all of their first 21 donors had some form of neurodegeneration, and 12 had CTE. It’s an alarming figure, though it’s important to note that the sample is likely biased: as CTE can currently only be diagnosed after death, the participants’ families no doubt donated their loved one’s brains because they suspected something was wrong.

CTE is currently only a post mortem diagnosis. But researchers are working on ways to be able to clinically determine if someone has the disease in the same way we do for Alzheimer’s. Some promising avenues of research are blood biomarkers, and specific markers for use in PET imaging.

But when it comes to treating CTE, Corrigan suggests there’s still a long way to go.

“If you look at Alzheimer’s disease, which we’ve known about for a lot longer, we’re still not there in terms of having any treatments that can slow down the progression of the damage to the brain,” she says. “They’re very complex diseases.”

It’s uncertain why only some people develop CTE. Not everyone who plays contact sports or experiences head knocks ends up with cognitive impairment. A recent study by Corrigan’s team suggests that genetic or epigenetic risk factors may be involved.

“What separates the people that get a neurodegenerative disease from the ones that don’t?” she asks.

Once we know, “we can get a better understanding of how the disease develops, and we’re potentially able to identify it earlier and come up with different treatments”.

“What separates the people that get a neurodegenerative disease from the ones that don’t?”

In the meantime, it’s important that player concussions are minimised, as well as ensuring that those who do end up concussed are treated effectively.

Firstly, it’s vitally important that people who have experienced a concussion avoid a second one while the brain is still recovering, as the damage from this second concussion can significantly exacerbate the first.

If someone does get a concussion, most professional sports now have protocols in place to prevent the player returning to play before they have recovered: players need to be cleared by a doctor before returning to any type of contact, and only when symptoms have abated.

“If you get a second injury during that recovery period then the damage is greater than if you had two spaced further apart. The brain’s energy reserves aren’t back to normal,” says Corrigan.

“Those axons are still recovering. If you’re going to run on a broken leg that hasn’t healed yet, of course you’re going to cause more damage to the break. It’s the same for the brain.”

Corrigan believes we’ve gotten much better at treating concussion and understanding these injuries.

“It’s important to understand why players are being asked to sit out for the two weeks. Don’t try to hide symptoms or downplay symptoms because you want to get out and play,” she says.

“You don’t have to sit in a dark room for the two weeks … Pay attention to what your body is telling you. If you’re tired, having difficulty concentrating, having problems with sleep, then give your brain time to recover.”

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