Trial to Test Slow-Oscillatory Brain Stimulation for Sleep and Cognitive Complaints in Older Adults

Researchers have outlined the design of a randomized, double-blind, sham-controlled clinical trial that will test high-definition slow-oscillatory transcranial direct current stimulation (so-tDCS) in right-handed Chinese older adults who experience both subjective cognitive decline and sleep disturbances. The protocol, registered with ClinicalTrials.gov under identifier NCT07433738, is a study plan rather than a report of results, so no conclusions about the technique’s effectiveness can yet be drawn.

Subjective cognitive decline is described in the protocol as an early and potentially modifiable stage in the trajectory of neurodegenerative diseases. The authors note that in older adults with this condition, untreated sleep disturbances may accelerate the neurodegenerative process, potentially through mechanisms involving amyloid-beta accumulation, and contribute to more rapid cognitive deterioration. They also observe that non-pharmacological treatment options that concurrently address subjective cognitive decline and sleep disturbances remain scarce. High-definition slow-oscillatory so-tDCS is characterized as an emerging, frequency-specific neuromodulation technique designed to enhance brain health and cognition.

Under the planned methods, 80 participants will be randomly assigned in equal groups of 40 to receive either active high-definition 0.75 Hz so-tDCS or sham stimulation over a four-week intervention period. Outcome measures will include galvanic skin response, subjective cognitive complaints, sleep quality, salivary amyloid-beta levels, and domain-specific cognitive performance. These outcomes will be assessed at four time points: baseline, week 4 immediately after the intervention ends, and follow-up visits at weeks 8 and 12.

A distinctive feature of the protocol is the personalized monitoring of neurophysiological signals during stimulation. Electrode-skin impedance will be tracked using what the authors describe as state-of-the-art measurement. They state that successfully implementing this signal would give researchers an add-on setting that allows them to evaluate real-time neurophysiological signals easily, quickly and quantitatively, which could facilitate the incorporation of transcranial brain stimulation into clinical practice.

Because this is a published study protocol, the reported content covers the trial’s rationale, design, participant criteria, intervention schedule and planned assessments. Whether active so-tDCS improves sleep, subjective cognitive complaints, amyloid-beta levels or cognitive performance in this population will only be known once the trial is completed and its results are analyzed and reported.

Subject of Research: A randomized controlled trial protocol testing slow-oscillatory transcranial direct current stimulation in older adults with sleep and subjective cognitive complaints.

Article Title: Personalized assessment of high-definition slow-oscillatory transcranial direct current stimulation (so-tDCS) in older adults with sleep and subjective cognitive complaints: A study protocol for a randomized clinical trial

Article References: Lu, H., Ni, X., Yang, N. S., Yuen, Y. S., Gong, Y., & Ma, S. L. (2026). Personalized assessment of high-definition slow-oscillatory transcranial direct current stimulation (so-tDCS) in older adults with sleep and subjective cognitive complaints: A study protocol for a randomized clinical trial. PLOS One, 21(10), e0360573. https://doi.org/10.1371/journal.pone.0360573

Image Credits: AI Generated

DOI: 10.1371/journal.pone.0360573

Keywords: so-tDCS, transcranial direct current stimulation, subjective cognitive decline, sleep disturbances, older adults, randomized clinical trial, neuromodulation, amyloid-beta, electrode-skin impedance, study protocol, Personalized, assessment