Examination of the effect of Deep Micro Vibrotactile stimulation on cognitive function for elderly with Alzheimer’s Disease

This study aimed to preliminary examine the effect of DMV stimulation on cognitive function in the elderly with moderate dementia. In the single arm study, 5 participants over 85 years old (% female: 100%) with Alzheimer’s disease completed treatment of DMV stimulation with 15-40 Hz. 15-40 Hz DMV stimulation was provided during the entire day for 4 weeks. We evaluated therapeutic effi cacy on cognitive function including WM, trail making test-part A & part B and the symbol digit substitution task in the participants, comparing outcomes at baseline with those after the 4 weeks intervention. According to statistical analyses, the WM improved signifi cantly after the intervention (p = 0.043), and the others didn’t have signifi cant improvement. Our result showed that this DMV stimulation might have potentially positive impact on cognitive memory function in older adults with moderate level of dementia. In conclusion, living environmental intervention utilized 15-40 Hz DMV stimulation can contribute to the new nonpharmacological treatments without invasiveness for the elderly with dementia. Short Communication Examination of the effect of Deep Micro Vibrotactile stimulation on cognitive function for elderly with Alzheimer’s Disease Ayuto Kodama1, Yasuhiro Suzuki2, Yu Kume3 and Hidetaka Ota1* 1Advanced Research Center for Geriatric and Gerontology, Akita University, Japan 2Department of Complex Systems Science, Graduate School of Information Science, Nagoya


Introduction
Deep Micro Vibrotactile (DMV) stimulation is an ultra-bass / non-audible sound of 40 Hz or less and a low sound that belongs to non-audible range in human being [1]. 40 -Hz oscillation of DMV stimulation is suggested to present at many levels in central nervous system and the vibrotactile stimulation can generate cognition in humans [2]. An intervention study utilized DMV stimulation for Alzheimer's Disease (AD) patients have reported that sound driven vibrotactile stimulation of the somatosensory system at 40 Hz can potentially enhance the electropotential power in AD patients (e. g. n = 18) and may, accordingly, contribute to improvement in cognition [3]. In a study of Clements-Cortes A, et al. unclear. Despite advanced pharmacotherapy in AD patients [4], currently there is substantial interest focused on non-invasive treatment to drive brain activity in 45 Hz DMV stimulation.
Thus, the purpose of this study is to evaluate effect of 15-40   When the sound pressure of low-frequency sound is intense, it vibrates the generator's housing, windows, and doors.

Participants
DMV is at sound pressure that does not cause such vibration.
Generally, a low-frequency sound of 20 Hz may generate vibration at a sound pressure at 80 dB or more. Whether or not the exposed DMV exists in the space, we examine acoustic sound or investigation with a low-frequency microphone. In this study, to perform acoustic analysis, room sounds with and without DMV were recorded and compared and analysed using acoustic analysis software (such as Audacity). Hearing 40 Hz to Alzheimer rats reduced amyloid-beta accumulation [6], which

Results
Five participants completed the 4 weeks follow-up. Table  2 shows a result of pre-and post-intervention. Only the WM signifi cantly improved after the 4 weeks intervention (p = 0.043) but the other domains including TMT-A, TMT-B and SDST didn't have signifi cant improvement.

Discussion
A result of this study suggest that 15-40 Hz DMV stimulation can increase short-term memory function as indicated in improvement of WM. Of limited information on effect of 40 Hz stimulation to cognition in AD patients, Clements-Cortes, et al. study [3] reports that a total score of Saint Louis University Mental Status (SLUMS), which includes orientation, shortterm memory, calculations, naming of animals, clock drawing and recognition of geometric fi gures, tends to be increased in each AD patient (n = 18) after the 6weeks intervention (e.g. two times per week for 6 weeks) included either 30 min of visual stimulation or 30 min of 40 Hz stimulation [3]. Because Clements-Cortes, et al. [3] didn't applied the pre-and posttest to assess effect size for each AD groups (mild, moderate, severe), a result of moderate AD patients in our study couldn't directly compare with the previous fi nding of Clements-Cortes, et al. study [3]. However, our result raises the possibility that short-term memory can be enhanced throughout noninvasive environmental intervention utilized 15-40 Hz DMV stimulation. Relate to 40 Hz DMV stimulation, 40 Hz neural oscillation is frequently emitted from nerve cells with the activity of a healthy human brain, which is a fundamental role in the communication of information between nerve cells [8,9]. Furthermore, several studies have suggested that 40 Hz oscillation implicated in the intra-brain communication stimulates neural outgrowth [10] and may become a covariate of cognition, not limited to an induced sensory phenomenon [1]. Martorell et al. study (2019) reports that repeating at 20 Hz, 40 Hz, and 80Hz stimulation improves cognitive function in dementia mice. This study is improved memory for fi ve participants, we suggested that stimulation at 15-40 Hz may improve cognitive function for elderly as much as stimulation at 40 Hz [6]. The future research needs to be accomplished considering the follow; our study samples was small as well as a single group intervention without a control group. Therefore, future studies should be increase the number of subjects, especially including male subjects. Outcomes other than cognitive domains didn't also include for analysis. Although preliminary interview data from a caregiver of the facility included a positive comment on better sleep state during the night, effect of DMV stimulation upon awake and rapideyemovement sleep states associated with 40 Hz neural activity [2] warrants further investigation.

Conclusion
In conclusion, our fi nding would suggest that 15-40 Hz DMV stimulation might be of utility as one of nonpharmacological treatments to enhance short-term memory in AD patients.
However, the research limitation regarding the small-sized sample, no control group and effect of parameters other than cognition in AD needs to be considered in the future study.