Strengths and weaknesses of transcranial ultrasound stimulation and its promise in psychiatry: an overview of the technology and a systematic review of the clinical applications.

This article reviews early studies that have demonstrated the ability of low intensity ultrasound waves to modulate brain activity. It also reviews the technological developments that have enabled transcranial ultrasound stimulation (TUS) to achieve millimetric spatial accuracy. This allows precise, noninvasive and reversible brain stimulation, a unique capability when compared to existing techniques such as transcranial magnetic stimulation, transcranial direct-current stimulation, and deep brain stimulation with implanted electrodes. TUS is now technologically ready for clinical translation. As psychiatric disorders have a high prevalence in the general population, and suffer from unmet noninvasive deep brain stimulation clinical needs, this article focuses on the potential application of TUS in psychiatry and reviews recently published clinical proofs of concept that have addressed depression, anxiety, schizophrenia and substance use disorders. Finally, the strengths and weaknesses of TUS technology are discussed, with reference to its clinical translation.