Millions of people around the globe are currently living with Parkinson’s disease, a multifactorial and incurable neurodegenerative condition that is associated with more than 40 different cognitive and physical symptoms. Symptoms can negatively impact the quality of life of those living with the condition, and the most common of these is tremor, characterised by persistent and irrepressible shaking of the limbs, typically the hands. However, other symptoms such as bodily stiffness, memory deficits, pain, and anxiety are also frequently reported. The manifestation of such disruptive symptoms is reflective of the irreversible neurodegeneration of the substantia nigra, a region deep within the brain that plays a role in movement, learning, and emotional regulation through the production of a neurotransmitter called dopamine, which allows neurons to communicate and regulate motor functions.
Despite its worldwide prevalence and recognition for over two centuries, a treatment that targets the underlying neurodegeneration associated with Parkinson’s has not yet been discovered, placing dopamine-replacement medications and physiotherapy at the forefront of symptomatic management. While the condition is not fatal on its own, it is progressive and can lead to devastating, potentially lethal complications. According to a study cited by Parkinson’s UK, it is estimated that the number of those living with Parkinson’s could be over 25 million globally in the coming 25 years, making the discovery of new and innovative treatments that tackle the neurodegenerative consequences of the condition vitally important.
Fortunately, researchers at Oxford University and University College London (UCL) have decided to address this urgent need by devising a non-invasive ultrasound helmet that sends high-frequency sound waves to modify how neurons in the brain communicate with one another. Their project spanned over a decade and achieved the development of a highly advanced version of transcranial ultrasound stimulation (TUS), a type of brain stimulation approach. The helmet has the capacity to be directed at brain regions nearly 1000 times smaller than the vast majority of ultrasound devices and 30 times smaller than well-established deep brain ultrasound devices, making it a perfect tool for targeting the small-scale substantia nigra, which typically cannot be modulated without surgical intervention.
Composed of over 250 different components, the helmet is able to modulate, or control, the levels of neuronal activity in targeted brain regions through beams of high-frequency sound waves. It utilises a mask that maintains the face in a fixed position within an MRI scanner, enhancing the specificity of the device. In their study, published by Nature Communications, the research group tested the device on the lateral geniculate nuclei of seven volunteers, with this region of the thalamus playing a crucial role in visual processing. The region was chosen due to its location in the centre of the brain, providing a means of determining whether the device could impact deep brain regions, such as the substantia nigra.
Two experiments were conducted, and they not only demonstrated the extraordinary precision of the device but also emphasised its potential to alter brain function long-term. The first experiment, which tested participants with a flickering image of a checkerboard, resulted in heightened activity only in the intended brain region, the visual cortex, post-stimulation with the device. The second experiment instead resulted in reduced visual cortex activity for over half an hour after stimulation, demonstrating long-lasting neuromodulatory effects induced by the helmet.
This helmet, with its extensive applicability, has the potential to treat other conditions, including depression, Tourette syndrome, and chronic pain. As the first technology to stimulate neurones in the human thalamus non-invasively but with high specificity, it led to the launch of NeuroHarmonics, a company founded by a number of UCL members involved in this study. The company aspires to create a less cumbersome model of the system and make it available for use in the medical field. Despite further research being required to determine how successful and safe the helmet is over a longer period of time, this remarkable innovation represents a massive leap in our understanding of neuromodulation strategies, exciting for its potential to revolutionise treatment for a range of neurological conditions.
With its promising results, the ultrasound helmet could even become a realistic alternative treatment option for those impacted by neurodegenerative disease and transform millions of patients’ lives.