Focused Ultrasound: Can Sound Waves Treat Depression?
- Erin Collins
- Jul 30
- 5 min read
I have always been fascinated by research that explores new ways of treating conditions that sit at the intersection of the mind and body. As our understanding of these complex relationships continues to grow, so does the potential for innovative and therapeutic approaches.
I am currently conducting a systematic review as part of my dissertation for the course, MSc Psychology and Neuroscience of Mind-Body Interface. My research focuses on the efficacy and safety of low-intensity focused ultrasound (LIFU) and high-intensity focused ultrasound (HIFU) as emerging therapeutic interventions for psychiatric disorders such as depression. By critically evaluating the existing evidence, I hope to understand whether these technologies have a credible role to play in the future of mental health care.
My research into focused ultrasound (FUS) has made me ask the question: can depression be treated with sound waves? Early-stage clinical trials suggest that this may be a possibility, although the evidence remains preliminary.
At present, focused ultrasound (FUS) is already in clinical use and trial settings within the UK, including through the NHS at selected specialised centres. It is primarily used to treat conditions such as prostate cancer, liver cancer, essential tremor and uterine fibroids. In psychiatric research, however, low-intensity applications are still experimental. FUS is being investigated for its ability to modulate neural circuits implicated in mood regulation, offering a non-invasive and non-damaging alternative to more established techniques.
Why Do We Need New Treatments for Depression?
Major depressive disorder (MDD), commonly referred to as depression, is a mood disorder characterised by persistent feelings of sadness, loss of interest, and other symptoms such as sleep disturbances and changes in appetite. Depression is often treated with medications called antidepressants. However, these medications do not work for everyone. It is estimated that approximately 30% of patients with MDD do not achieve an adequate response to antidepressants. In clinical settings, the estimated percentage of patients who do not respond to antidepressants jumps to 55%. To help support this sizeable treatment-resistant population, there is a need for the development of new treatments.
Low- and High-intensity Focused Ultrasound
LIFU uses ultrasonic sound waves (sound waves that are too high-pitched for humans to hear) to target precise brain regions in order to change how specific areas of brain cells communicate with each other.
Neurons are specialised brain cells that carry messages throughout the brain. They work together in complex networks to help us think, feel, and move. When these networks aren’t working properly, it can affect how the brain functions. LIFU aims to help by altering patterns of neural activity in specific brain regions. By influencing how neurons communicate, LIFU may help regulate the activity in brain regions involved in depression.
Unlike LIFU, HIFU causes a permanent change to the brain tissue. HIFU uses much stronger ultrasound waves to cause heat damage to targeted brain regions - this is known as irreversible thermal ablation. This makes HIFU an especially useful technique for precision tumour eradication.
Neuromodulatory Effects
One of the most promising effects of FUS in psychiatric disorders, such as MDD, is neuromodulation. Neuromodulation involves stimulating or pharmacologically influencing specific brain regions to alter brain activity. Evidence suggests that the acoustic pressure waves generated by FUS activate mechanosensitive ion channels, which are proteins found on cell membranes.
When mechanosensitive ion channels are activated, they convert the mechanical energy of ultrasound waves into electrical signals, altering the flow of ions (for example, calcium, sodium, and potassium ions) across the cell membrane which affects neuronal excitability. Depending on the stimulation parameters, FUS can either increase or decrease activity within targeted brain circuits, making it a promising tool for regulating brain networks disrupted in psychiatric conditions.
Focused Ultrasound Parameters
Scientists can control exactly how sound waves are sent. LIFU uses many different parameters, but these are the three main ones to know about:
1. Fundamental Frequency
This is the main ultrasound frequency used to reach the target area of the brain. It helps determine how deeply the sound travels and how precisely it can be focused.
2. Pulse Repetition Frequency
This is the number of pulses transmitted per second, controlling how often sound waves are sent.
3. Duty Cycle
This is the proportion of time that the ultrasound is switched ON versus the time it is OFF.
The pulse repetition frequency and the duty cycle work together to avoid tissue overheating by controlling how many pulses are given and how long they are active for, which gives the brain tissue time to cool down.
Three Key Features of Low-intensity Focused Ultrasound
It is Non-ablative: LIFU is not permanent. Researchers can control treatments, and if it does not work for a patient, the treatment can be stopped without the patient experiencing any permanent brain damage.
It is Non-invasive: LIFU does not require surgery or implantation. Although other non-invasive brain stimulation techniques exist, such as transcranial direct current stimulation and transcranial magnetic stimulation, these techniques are unable to stimulate deep brain structures such as the amygdala, the dorsal anterior cingulate cortex, and the subcallosal cingulate; brain areas which play a role in depression.
It Works With High Precision: The sound waves are set to target deep brain structures with incredible precision, to the millimetre. This means that specific deep-brain areas functionally involved in depression can be targeted by LIFU.
Where are we now with research on Low-intensity Focused Ultrasound in Depression?
LIFU has been evidenced to reduce depression scores in treatment-resistant case studies as well as larger trials. Most studies also suggest that LIFU is well-tolerated without major side effects. However, some patients have reported mild side effects such as headaches, anxiety, or discomfort during treatment.
Importantly, LIFU’s efficacy and safety are not restricted to MDD. LIFU has also been seen to be effective at improving other mental health disorders in clinical trials, such as treatment-resistant anxiety and substance use disorder.
There is still more research needed to find the ideal parameter settings for each patient. Future research is needed to understand how strong the sound waves should be, how many pulses to send, and how long the waves should be switched on for. Finding the right combination of parameter settings for each condition is an important next step for making LIFU as effective as possible.
LIFU is a promising new approach that could help people with depression and other mental health conditions, particularly those who have not responded to existing treatments. It does not require surgery, offers high precision, and, importantly, is non-ablative (destructive/permanent). While further research is still needed, the results from clinical trials so far are encouraging, and we should be enthusiastic about LIFU as a technique in mental health care.
