Optimal treatment conditions for low-intensity pulsed ultrasound therapy for Alzheimer’s disease: applications from mice to humans

We previously developed a novel therapy with low-intensity pulsed ultrasound (LIPUS) that ameliorates cognitive decline through upregulation of endothelial nitric oxide synthase (eNOS) in mouse models of Alzheimer’s disease (AD). In a randomized, double-blind, placebo-controlled pilot trial, we demonstrated that whole-brain LIPUS therapy is safe and tends to suppress the cognitive decline in early AD patients. We herein report the findings of our basic experiments that we performed for the pilot trial in order to apply whole-brain LIPUS therapy to humans, as well. First, we examined the relationship between bone density/thickness and ultrasound transmittance using human temporal bone. Next, based on the results of ultrasound transmittance, we further examined mRNA expression of VEGF, FGF2, and eNOS in response to variable ultrasound frequencies, duty cycles, and sound pressures. There was a significant correlation between bone thickness and transmittance (1.0 MHz, P < 0.001), while there was no significant correlation between bone density and transmittance (1.0 MHz, P = 0.421). At a frequency of 0.5 MHz, the optimum duty cycle was considered to be up to 20