During his undergraduate course, Brenton Hordacre says he remembers being on his neurology rehab placement and thinking how much he was loving it and wanted to learn more.

‘Seeing people go from pretty poor situations in life, maybe unable to walk very far or return to their previous employment because of a brain injury, was confronting. However, celebrating the small, but significant, improvements during therapy was amazing.

'I just felt like rehab physios have huge potential for helping people achieve meaningful improvements in quality of life.’

And while neurological recovery can be slower than recovery from musculoskeletal injuries, Brenton likes the opportunities this presents—getting to know the patient, understanding their family situation, their struggles, where they’ve come from and what motivates them to persist in their recovery.

Equally, he derives great satisfaction when patients achieve their goals, like learning to walk again or getting back into social activities.

‘I found that very rewarding as a physio, so I’ve always been quite intentional about working in a rehabilitation environment. Any future study, such as a PhD, was always going to be centred around rehabilitation.’

His PhD focused on people with lower limb amputations and assessing brain changes as they were learning to walk with a prosthetic leg.

Since that time, his research has focused on stroke and what happens to the brain over the recovery period.

‘It is a privilege working with amputees and stroke survivors. As rehab clinicians, we have the chance to work very closely with patients and see meaningful and positive life-changing events happen,’ Brenton says.

‘Equally, as a researcher it’s a real privilege that people choose to volunteer for our studies.

'Even though it can be challenging for many of these patients to leave their home, they willingly volunteer their time to come in, be tested, poked and prodded and provide feedback.

While it is amazing to see the positive results, I will be forever grateful to the many people who have made these research projects possible.’

His quest for knowledge has moved into looking at new treatment techniques and ways to enhance therapy—how treatments work, what’s happening in the brain and how that improves someone’s behaviour.

Brenton runs a technology clinic at University of South Australia where the treatments they test, evaluate and prove to be effective can then be offered to the community.

The clinic currently offers a robotic device for upper limb rehab and brain stimulation for post-stroke depression.

‘The motivation for establishing this clinic came from one of the study participants who was adamant that we needed to provide some of these treatments to people in the community.

'From my perspective, it is also pleasing to know that participants in our studies are contributing to understanding a treatment that can be rapidly offered to others in the community.

'It also serves as a nice feedback loop because the participants who come to the clinic can tell us what they think about the treatment,’ says Brenton.

‘Often with research the focus is on whether the treatment is effective and how strong that effect is. While we are interested in these aspects, the clinic gives us a chance to delve a bit more deeply into what people actually think of these treatments.

'Is there another way we can tweak this to provide a better clinical service? It’s always nice to have a clinical impact in research and give back to the people that have volunteered to participate in lots of our studies.

'I think the study participants are really pleased that they can see there’s a direct line to improving health for people with stroke.’

In 2015, Brenton was awarded a Physiotherapy Research Foundation (PRF) Seeding Grant, which contributed to research focused on understanding how to stimulate the brain in healthy adults in order to change brain activities.

Brenton and his team refined the brain stimulation technique and then used it in his second trial, titled ‘Evidence for a window of enhanced plasticity in the human motor cortex following ischemic stroke’, to assess neuroplasticity in patients with stroke.

‘Through the PRF funding, it gave us an indication of the best way to assess neuroplasticity, and then we used that assessment of neuroplasticity in the stroke study. Our study revealed that there is a period of enhanced plasticity that seems to peak at about two-to-six weeks after stroke.’

The clinical impact of this research is far-reaching. ‘We know that neuroplasticity absolutely underpins behavioural change in recovery from stroke,’ Brenton explains.

‘So if we have a window of time between two-to-six weeks after stroke where the brain has greater capacity for neuroplasticity, then therapy delivered at this time is critical. That’s the opportunity to make real change.’

Brenton reiterates that rehabilitation is still beneficial outside this period of enhanced neuroplasticity.

‘It doesn’t mean that if you start rehab outside of this window that there isn’t opportunity for recovery.

'There’s nothing wrong with starting therapy before two weeks and extending beyond the six week mark.

'Because the capacity for neuroplasticity and neural changes is greatest in that two-to-six week period, that’s where we would hope to see people getting high doses of therapy and really take advantage of that natural, spontaneous process that’s happening in the brain.

'But outside that window, you can still see improvements; it’s just slower and might require a lot more therapy dose.’

At the University of South Australia clinic, Brenton’s works with patients with chronic stroke, and looks at new technologies or therapies to increase treatment dose and to reopen the period of plasticity to allow a better response to the therapy.

As Brenton explains, one possible way to reopen that window is through a brain stimulation technique.

During COVID, Brenton ran another study (soon to be published) that looked at a home-based brain stimulation program in people with chronic stroke. Participants were given a brain stimulator to take home.

‘The patients did brain stimulation at the same time as an upper limb rehab program. The idea here is the brain stimulation would promote neuroplasticity, re- opening a window where recovery can accelerate and the response to the rehab program would be greater.’

The placebo group also had a brain stimulator placed on their head and completed the rehab exercises, but the brain stimulator was programmed not to apply any current.

‘What we found’, says Brenton, ‘was there was a significant improvement in upper limb impairment for the people who had brain stimulation.

'It could be that this is a way to establish a period where the brain is more plastic so that the therapy is much more effective. And that’s what our data would say’.

Brenton’s team is also trialling several other ways of increasing brain neuroplasticity. One of these includes an immersive motor imagery task using virtual reality goggles.

While watching a half-hour video of someone performing upper limb tasks, trial participants imagine themselves replicating those tasks.

The aim is to target people with very little arm movement after stroke to see whether this immersive action observation can change brain activity and increase plasticity.

There are other opportunities on the horizon.

Brenton is currently in conversation with a couple of pharmaceutical companies about running a drug trial that might have the capacity to change neuroplasticity ‘whether it’s reopening a period of enhanced plasticity in chronic stroke or extending that one that occurs spontaneously between two to six weeks after stroke’.

Brenton says while some patients are open to the idea of drugs to help their recovery, others are not, so broad strategies are needed to tackle this problem.

‘We’re also looking at cardiovascular exercise because there’s good evidence just doing exercise increases brain plasticity, but it can sometimes be challenging to get a stroke patient to do high-intensity training because they’re exhausted.

'So you can see the need for multiple strategies to promote positive brain changes.’

There are currently more than 500,000 stroke survivors in Australia and that’s tipped to reach one million in the next few years because, as Brenton says, ‘while stroke survival rates are improving, we need better solutions for recovery to help people once they leave the hospital.

'If you look at the numbers, stroke is tracking on par with dementia. Stroke is going to be an equally challenging problem for our society in the future. My hope is that some of the work we do will help address this problem.’