Depression, a pervasive mental health disorder, affects millions worldwide. In France alone, 12.5% of the French population had experienced a depressed episode characterized during the year in 2021. Current treatments, including medication, often take weeks to show effects, and a significant portion of patients, nearly a third, do not respond adequately. This has spurred researchers to explore innovative therapeutic avenues, including ultrasound stimulation of deep brain regions.

The Challenge: Targeting Deep Brain Regions Non-Invasively

historically, stimulating these brain regions required invasive procedures involving intracerebral electrodes, posing considerable neurosurgical risks.The new approach uses low-intensity focused ultrasound to stimulate the brain. According to Inserm, Ultrasounds have the property of spreading in human tissues and stimulating the brain area on which they are concentrated, by mechanical action, by triggering the opening of mechano-sensitive channels. However, the skull’s irregular thickness presents a significant obstacle, distorting ultrasound waves and hindering precise targeting.

The Solution: Tailor-Made Acoustic Lenses

Researchers from GHU Paris, Inserm, CNRS, Paris Cité university, and ESPCI Paris-PSL have developed a groundbreaking solution: acoustic lenses. These lenses compensate for the distortions caused by the skull’s irregularities,allowing for precise ultrasound targeting. Psychiatrists Marion Plaze and David Attali modeled the effect of the skull on ultrasound for each patient, enabling the creation of custom-designed acoustic lenses. The technology behind these lenses was developed at the Physical Institute for Medicine (Inserm, ESPCI Paris-PSL, CNRS) by researchers and engineers Jean-François Aubry (CNRS), Thomas Tiennot (ESPCI) and Mickael Tanter (Inserm). This patented technology has led to the founding of a start-up to accelerate its clinical application.

Clinical Trial Results: A Promising Start

A clinical trial involving five patients with severe, drug-resistant depression yielded encouraging results.The treatment, administered over five consecutive days, caused no discomfort or pain, and no serious adverse events were reported. The results, published in the journal Brain Stimulation, indicated a significant reduction in depression severity. The severity scores of depression have gradually decreased over the days of treatment, with an average reduction of more than 60 % of the severity of depression on the fifth day of the protocol.

Future Implications: Expanding the Scope of Ultrasound Therapy

While the initial study involved a small number of patients and lacked a placebo group, further trials are planned to confirm the safety and long-term efficacy of transcranial ultrasound stimulation. If these trials prove successful, the technique could revolutionize the treatment of various neurological and psychiatric disorders. The potential applications extend beyond depression, encompassing psychiatry, addictology and neurology, for the benefit of many patients.

Sources: Inserm, Brain Stimulation