Focused ultrasound and Parkinson’s: what does the research say?

Parkinson’s is a condition which affects the brain. Over time, cells deep in the brain become damaged and are lost. The cells affected are those which produce an important chemical called dopamine, which helps send signals around the body. As these cells die, less dopamine is available for the brain to use, and symptoms of Parkinson’s develop.

For most people with Parkinson’s, symptoms can be managed by medication that boosts the amount of dopamine in the brain. However, the effectiveness of these medications can reduce over time, making symptoms difficult to control. To overcome this, researchers are exploring other options to target affected brain cells directly.

But it’s very difficult to find treatments that reach affected areas directly, as the brain is well protected by bones and tissues such as the skull. This means that treatments other than medications often need invasive surgery, such as required for deep brain stimulation (DBS).

Focused ultrasound poses a new opportunity to change this. The technique has garnered a flurry of interest due to its potential to reach cells deep in the brain without the need for surgery. Let’s explore what focused ultrasound is, what the research tells us, and what it could mean for people with Parkinson’s.

What is focused ultrasound?

Focused ultrasound is a technique that uses high power sound waves to remove problematic cells in the body. The sound waves used are 40,000 times stronger than those used in regular ultrasound, which is a technique used to see inside the body, such as in a scan to see how an unborn baby is growing.

In focused ultrasound, the sound waves can be directed to very specific areas in the body. The sound waves are guided by magnetic resonance imaging (MRI), which helps to create a detailed image of the brain. The powerful sound waves heat up cells in the target area to very high temperatures, destroying their structure and causing them to die.

The technique is exciting because it not only enables damaged cells in the body to be removed, but also because the high powered sound waves are able to pass through the skull and reach cells deep in the brain. This means it can be done in a non-invasive way, removing the need for surgery and general anaesthesia.

Why is focused ultrasound being looked at for Parkinson’s?

Focused ultrasound may benefit people with neurological conditions, including Parkinson’s, because it provides a way to remove brain cells which may be causing problems. For Parkinson’s, these could be cells in areas of the brain that control movement symptoms, like tremor or rigidity.

In the UK, focused ultrasound is already an NHS approved treatment for a movement condition called essential tremor. For some people, the condition can be well managed by destroying cells in an area of the brain that controls movement. The benefits of focused ultrasound for Parkinson’s, however, are not well understood. Large research studies are needed to assess whether focused ultrasound could become a treatment for people with Parkinson’s in the UK.

What does the research say?

Previous research studies

In 2018, a small pilot study investigated the safety and effectiveness of focused ultrasound for Parkinson’s. 10 people with Parkinson’s who experienced movement symptoms that were not well managed by medication underwent focused ultrasound. Participants were then monitored for 6 months. The severity of movement symptoms were measured using the MDS Unified Parkinson's Disease Rating Scale (MDS-UPDRS). At the 6 month mark, the average MDS-UPDRS score improved by 53%, meaning that the treatment seemed to improve movement symptoms. The small study also provided evidence that focused ultrasound was safe for people with Parkinson’s. Read a summary of the pilot study in The Lancet Neurology Journal.

Similar results were published following a small, randomised study involving people with Parkinson’s in 2020. Of 40 participants, 27 received focused ultrasound and 13 were in the placebo group, receiving a similar procedure but not undergoing focused ultrasound. Those in the treatment group saw an improvement to movement symptoms after 4 months, with the average MDS-UPDRS score improving. Whilst the treatment was deemed effective, people who’d undergone the treatment did experience some side effects. This included speech and walking problems, weakness, and dyskinesia (uncontrolled movements). Read a summary of the research in the New England Medical Journal.

In 2023, a team of researchers based in the USA published a larger study which reported that focused ultrasound showed promise for people with Parkinson’s with movement problems, for up to a year after treatment. In the study, 94 people with Parkinson’s experiencing movement symptoms were split into 2 groups. 69 people received focused ultrasound therapy and 25 people were in the placebo group. After 3 months, 45 people in the focused ultrasound group showed improvements in their movement, and 30 of these people were still seeing improvements 1 year after receiving the therapy. However, for others the therapy made little to no difference to their movement symptoms. Some people also experienced side effects such as problems with walking, vision and loss of taste. Read a summary of the research in the New England Medical Journal.

Ongoing research

In the UK, Dr Tom Gilbertson at the University of Dundee is also studying the safety and effectiveness of focused ultrasound for Parkinson’s. The study aims to understand whether focused ultrasound can specifically reduce tremor for people with Parkinson’s. Tremor (shaking) is one of the main symptoms of Parkinson’s and affects a part of the body, for example the hand or arm. During the study, participants will receive a single treatment of focused ultrasound on one side of the brain only. The aim is to reduce the tremor on the opposite side of the body by 50%. The study will conclude in 2027.

Does focused ultrasound come with any risks?

One limitation of studies investigating focused ultrasound for Parkinson’s is that often, such as in the UK trial, the treatment is only applied to one side of the brain. This is because focused ultrasound is a permanent treatment and does come with risks. Severe side effects, such as developing balance and speech problems, are more likely when performed on both sides. This means that for now, focused ultrasound only has the potential to reduce symptoms on one side of the body. For people with Parkinson’s, however, movement symptoms tend to affect both sides.

What are the next steps and what does this mean for people with Parkinson's?

The research so far has shown that focused ultrasound can be effective for some Parkinson’s symptoms. But there’s a lot we still don’t know. Research investigating using focused ultrasound on both sides of the brain is in its infancy, but it promises to become a more active area of research in the future. We also don’t know what the long term impact of focused ultrasound on Parkinson’s symptoms might be - how long they last, and whether there are any side effects over time.

In the USA, the Food and Drug Administration (FDA) has approved focused ultrasound as a treatment for Parkinson’s. However, focused ultrasound isn’t approved by the UK’s National Institute of Health and Care Excellence (NICE). This means it’s not an approved treatment for Parkinson’s in the UK and isn’t available on the NHS.

NICE have published guidelines on the use of focused ultrasound for Parkinson’s. The guidelines outline the need for more controlled research before focused ultrasound can be approved as a treatment and also suggest that the procedure should currently only be carried out as part of a research project, ensuring it’s delivered safely in a controlled environment.

With more and more research in this area, and previous studies showing encouraging benefits, focused ultrasound has the potential to change the treatment pathway for Parkinson’s and provide new options for people in the future.