Differing effectiveness of transcranial random noise stimulation and transcranial direct current stimulation for enhancing working memory in healthy individuals: a randomized controlled trial.
Yukina Tokikuni, Akihiro Watanabe, Hisato Nakazono and 11 others
PMID 39402554WHAT IT FOUND
Transcranial random noise stimulation improved accuracy during the task compared to sham, but showed no benefit after stimulation ended.
Direct current and noise-with-offset failed to improve performance. This effect was limited to healthy young adults and did not speed up responses.
Key findings
01High-frequency transcranial random noise stimulation (tRNS) significantly improved accuracy (d-prime score) on the dual n-back task during stimulation compared to sham.
02Transcranial direct current stimulation (tDCS) and tRNS with a DC offset did not show significant differences in accuracy compared to sham during or after stimulation.
03No stimulation type significantly improved response time compared to sham, although all active groups showed faster responses after stimulation compared to during stimulation.
STILL TO COME
How it was doneWhat they found
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What it does not show
The study was conducted only on healthy young adults (mean age 22.56 years), so it is unclear if these results apply to older adults or clinical populations with cognitive decline. The effects were measured immediately during and after a single 20-minute session, providing no information on the durability or long-term benefits of the stimulation. There were no standardized protocols for tRNS, making it difficult to compare these results with other studies or determine if the parameters used were optimal. Electrode placement was based on standard scalp coordinates rather than individual brain structure, which may affect the precision of stimulation. The study used a specific working memory task (dual n-back), and results may not generalize to other types of cognitive tasks or daily functioning.
Declared interests
The study was funded by the Japan Society for the Promotion of Science. The authors declared no conflicts of interest.
The easy way to misread this
Do not interpret the significant improvement in accuracy during stimulation as evidence that tRNS is an effective clinical intervention for working memory deficits. The effect was transient, disappearing immediately after stimulation, and was observed only in healthy young adults. Furthermore, tDCS, a more commonly used technique, showed no benefit over sham in this study.