Long Term Transcranial Pulse Stimulation (TPS) on Older Adults With Mild Neurocognitive Disorder (NCD)

Background:Dementia, now known as major neurocognitive disorder (NCD), is a great health burden in Hong Kong and worldwide. In principle, to achieve its optimal benefits, intervention for dementia should begin at the earliest preclinical stage, which is defined as mild cognitive impairment (MCI). However, no evidence has been found to support a pharmacological approach to the prevention or postponement of cognitive decline during the stage of mild NCD. Non-invasive brain stimulation (NIBS) is increasingly recognized as a potential alternative to tackle this problem.The typical examples of NIBS are transcranial direct current stimulation (DCS) and transcranial magnetic stimulation (MS). Besides these, there is a new NIBS named transcranial pulse stimulation (TPS), which recently obtained CE marking in 2018 for the treatment of the central nervous system (CNS) in patients with mild to moderate Alzheimer's disease (AD). TPS is using repetitive single ultrashort pulses in the ultrasound frequency range to stimulate the brain. With a neuro-navigation device, TPS can achieve this in a highly focal and precisely targeted manner. TPS differs from DCS and TMS using direct or induced electric current. Instead, TPS provides good spatial precision and resolution to noninvasively modulate subcortical areas, despite the problem of skull attenuation. Using lower ultrasound frequencies TPS can successfully improve skull penetration in humans. TPS has shown its neuroprotective effects through inducing long term neuroplastic changes, supported by neuropsychological tests and neuroimaging investigations both in animal and human studies.Mild NCD is a golden period for intervention to avoid further progression to dementia. Although TPS has great potential as a new treatment option due to its neuroprotective effects, there is no TPS study done on mild CD subjects according to our knowledge. To determine the effectiveness of TPS in mild NCD, an open-label pilot study was conducted by our team from Dec 2020 to Dec 2021. The preliminary result was presented in the 2021 Brain Stimulation Conference and published in abstract format. We recruited 16 older adults who had mild CD. They received 6 sessions of TPS over 2 weeks.Assessments were done at the 3 time points. No subjects dropped out during the study. Statistically significant improvement was found in the primary outcome, HK-MoCA, from 18.06 to 20.25. The improvement was maintained till 12 weeks after the TPS intervention. No adverse effect was observed. The result suggested that TPS is likely to have an immediate effect on global cognition in mild CD, and the improvements were sustainable. However, a 2-week treatment duration may not be long enough to induce a significant change in neurodegenerative disease in long term. Up to date, there is no long-term NIBS treatment done on NCD. Therefore, we plan to conduct a pilot case-controlled trial to evaluate the efficacy of long-term TPS on cognition and brain structure in patients with mild ND based on the results of our pilot study.Objective:This study is to determine the efficacy of a 24-week program (32 sessions) of TPS in older adults with mild NCD. We hypothesized that TPS group is significantly more effective than control group in maintain or improve the global cognitive function measured by Hong Kong Chinese version of Montreal Cognitive Assessment (HK-MoCA) in patients with mild NCD.Design:This case-controlled trial will assess the efficacy of a 24-week TPS program on cognition and brain structure in subjects with mild NCD. All eligible participants will receive an intervention trial of TPS. They would receive 2 sets of stimulation programs, each set lasting 12-weeks. Participants would receive 3 sessions/week in the first 2 weeks and then 1 session/week in the subsequent 10 weeks. A total of 32 sessions (2 sets of 16 sessions) ofTPS will be delivered, with each session lasting 30 minutes.Data Analysis:The primary and secondary outcomes will be assessed at baseline, immediately after the 1st set of stimulation program (12th week), 2nd set of stimulation program (24th week), and 12 weeks after the intervention (36th week). The primary outcome will be the change of the Hong Kong Chinese version of the Montreal Cognitive Assessment (HK-MoCA). The secondary outcome includes specific cognitive domains, daily functioning, mood, and apathy. The intention-to-treat analysis would be carried out. Pre and post-intervention brain MRI scans will be used during the intervention to evaluate the changes in brain structure. A checklist of potential adverse effects associated with TPS administration will be generated from the available literature. Blood pressure and heart rate will be recorded at the beginning and at the end of the TPS intervention course.

Inclusion Criteria:60 years of age or aboveChinese ethnicityFulfil the criteria of mild neurocognitive disorder (NCD), defined by the DSM-5Stable dosage/frequency of anti-dementia therapy or other treatments for mild NCD in recent 8 weeksValid informed written consentExclusion Criteria:HK-MoCA score below the second percentile according to the subject's age and education level (to exclude subjects with existing major NCD/dementia)Alcohol or substance dependenceConcomitant unstable major medical conditions or major neurological conditions such as brain tumour, recent strokeHaemophilia or other blood clotting disorders or thrombosisSignificant communicative impairmentsParticipants with any metal implant in brain or treated area of the head