Transcranial Ultrasound (TUS) Effects on Mental States: a Pilot Study

Background/objective: Transcranial ultrasound (TUS) can modulate brain function. To assess possible TUS modulation of mental states, we investigated effects on subjective reports of pain and mood of sub-thermal TUS versus placebo applied to frontal scalp and brain of chronic pain patient volunteers.

Methods: With IRB approval and informed consent, subjects with chronic pain completed two visual analog scales for pain (NRS) and mood (VAMS/Global Affect), and their vital signs were recorded 10 min prior to, and 10 min and 40 min following exposure to either subthermal TUS (8 MHz) or placebo (in a double blind crossover study) using the 12L-RS probe of a LOGIQe ultrasound imaging machine (General Electric, USA). A physician, also blinded for TUS versus placebo, applied the probe (with gel) to scalp over posterior frontal cortex, contralateral to maximal pain, for 15 seconds. A second investigator operated the ultrasound machine, randomizing TUS versus placebo. The process was then repeated, applying the opposite modality (TUS or placebo).

Results: Subjective reports of Mood/Global Affect were improved 10 min (P = 0.03) and 40 min (P = 0.04) following TUS compared with placebo. NRS pain reports slightly improved following TUS (P = 0.07) at 40 min.

Conclusion: We found improvement in subjective mood 10 min and 40 min after TUS compared to placebo. TUS can have safe neurophysiological effects on brain function, and is a promising noninvasive therapy for modulating conscious and unconscious mental states and disorders. We suggest TUS acts via intra-neuronal microtubules, which apparently resonate in TUS megahertz range.