rTMS Boosts Slow-Wave Activity and Processing Speed in Older Adults with Cognitive Decline
A single session of repetitive transcranial magnetic stimulation (rTMS) applied to the left dorsolateral prefrontal cortex increased slow-wave activity (SWA) during subsequent sleep and was associated with improved processing speed in older adults with subjective cognitive decline, according to a proof-of-concept pilot randomized controlled trial published in the Journal of NeuroEngineering and Rehabilitation.
The findings offer preliminary evidence that non-invasive brain stimulation can enhance sleep-related cognitive processes in aging populations, potentially opening a non-pharmacological route to supporting cognitive function in older adults at risk for decline.
What the Study Found
Researchers at the University of Pittsburgh enrolled 20 older adults with subjective cognitive decline (mean age 70, SD 5.2) and randomly assigned them to receive either active rTMS (n=11) or sham stimulation (n=9). Participants received a single 40-minute session of 10 Hz rTMS targeting the left dorsolateral prefrontal cortex. They spent two nights in a sleep laboratory with high-density EEG recording — one night before stimulation and one night after. A cognitive battery assessed memory retention, executive function, and vigilant attention.
The active rTMS group showed significant improvement in Stroop reaction time, a measure of processing speed, compared with the sham group. This improvement was associated with increased fronto-parietal slow-wave activity during the first NREM sleep period following stimulation.
Secondary analyses revealed that the processing speed benefit extended to Stroop congruent and neutral trials, and also correlated with faster reaction times on a Sternberg working memory task. However, the study found no significant effects on memory retention or other executive function measures.
Why It Matters
Slow-wave activity during non-REM sleep is a well-established marker of synaptic homeostasis and is thought to support memory consolidation and cognitive function. Previous work has demonstrated that increasing SWA in young adults can enhance memory and cognitive performance, but the relationship has remained poorly characterized in older populations, where both SWA and cognitive function naturally decline with age.
This study provides proof-of-concept that rTMS can acutely increase SWA in older adults and that this increase is functionally relevant — tied to measurable improvements in processing speed. If confirmed in larger trials, the approach could represent a scalable, non-pharmacological intervention to support cognitive health in aging.
Limitations
The authors emphasize that this is a pilot study with important limitations. The sample size was small (n=20), the intervention consisted of only a single rTMS session, and the study did not demonstrate improvements in memory retention or broader executive function. Without evidence of durable cognitive enhancement beyond processing speed, the clinical relevance of the observed effects remains to be established. The findings require replication in larger, multi-session trials with longer follow-up.
Bottom Line
This proof-of-concept study demonstrates that a single session of rTMS to the left DLPFC can increase fronto-parietal slow-wave activity during sleep in older adults with subjective cognitive decline, and that this increase is associated with improved processing speed. The results provide a rationale for larger randomized controlled trials with multi-session rTMS protocols to determine whether sustained enhancement of slow-wave activity can produce clinically meaningful cognitive benefits in aging populations at risk for decline.
Source
Stepan ME, Mayeli A, et al. Effects of repetitive transcranial magnetic stimulation on cognition through sleep slow-wave activity in older adults. J Neuroeng Rehabil. 2026 Jul 1. DOI: 10.1186/s12984-026-02064-w. PMID: 42387564.