An interventional study of Transcranial alternating current stimulation and Transcranial alternating current stimulation in Alzheimer Disease and Cognitive Decline, sponsored by The National Brain Mapping Laboratory (NBML). Completed at 1 site in Iran. Open to participants aged 50 Years to 85 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-03-18.
Sponsored by The National Brain Mapping Laboratory (NBML) · Not applicable, Interventional, and Basic science
This study aims to compare the efficacy of different 40 Hz tACS protocols in entraining gamma oscillations, which are linked to various cognitive functions and play a significant role in cognitive impairments like Alzheimer's disease. Specifically, it examines the effects of 40 Hz tACS applied to frontal brain regions versus fronto-temporal regions on gamma oscillations and working memory in healthy elderly individuals.
3,678 studies on the registry are indexed under Alzheimer Disease; 872 are open to participants now.
This study's enrollment of 30 is below the median of 70 across 2,808 interventional studies indexed under Alzheimer Disease.
Browse Alzheimer Disease studies →The National Brain Mapping Laboratory (NBML) is the lead sponsor of 11 studies on the registry; none are open to participants now.
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During prefrontal tACS, an alternating electrical current with a 1 milliamp peak-to-peak amplitude will be delivered, featuring a 15-second ramp-up at the start and a 15-second ramp-down at the end. The stimulation duration is 20 minutes and four channels are used for delivering sinusoidal alternating currents to the head. The alternating current was delivered to the prefrontal cortex bilaterally with the electrodes at F3 and F4 and the return electrodes were placed at the ipsilateral mastoids at TP9 and TP10 (international 10-20 EEG electrode placement system).
Device: Transcranial alternating current stimulation
During frontal-temporal tACS, an alternating electrical current with a personalized peak-to-peak stimulation intensity will be delivered, featuring a 15-second ramp-up at the start and a 15-second ramp-down at the end. The stimulation duration is 20 minutes and four channels are used for delivering sinusoidal alternating currents to the head. The alternating current was delivered to the prefrontal and temporal cortices with the active electrodes at AF3-T7 and the return electrodes over AF4-T8 (according international 10-20 EEG electrode placement system).
Device: Transcranial alternating current stimulation
During sham tACS, an alternating artificial electrical current will be delivered, only ramping the current for 15 seconds up and 15 seconds down at the beginning and end of the stimulation respectively.
Device: Sham Transcranial alternating current stimulation
Transcranial alternating current will be delivered utilizing a Starstim 8-channel constant current, battery-powered electric stimulator (Neuroelectrics, Barcelona, Spain). Circular carbon rubber electrodes (2cm radius, 12,57 cm2) are used throughout the stimulation.
Transcranial alternating current will be delivered utilizing a Starstim 8-channel constant current, battery-powered electric stimulator (Neuroelectrics, Barcelona, Spain). Circular carbon rubber electrodes (2cm radius, 12,57 cm2) are used throughout the stimulation.
Sham tACS will be applied by only ramping the current for 15 seconds up and 15 seconds down at the beginning and end of the stimulation respectively.
Working Memory behavioral performance
Participants view a continuous sequence of alphabet letters, presented as stimuli in Arial font, size 120pt, on a tube screen positioned at 60cm eye distance. The stimuli are shown with a time interval of two seconds between them. The task consisted of six blocks with 70 stimuli, including 12 possible hit trials. Participants were instructed to press the left key on a response box if the presented stimulus matched either the one presented one trial prior (1-Back) or three trials prior (3-Back). In all other cases, participants press the right key. The left button is pressed with the index finger, while the right button is pressed with the middle finger of the right hand, with buttons aligned horizontally. The response condition varied by block, with three blocks for 3-Back and three for 1-Back, and the order was counterbalanced across participants and sessions.
Time frame: During procedure (20 minutes)
electroencephalogram (EEG) oscillatory power
Change in the EEG power in the gamma band
Time frame: up to 2 hours after the intervention
electroencephalogram (EEG) functional connectivity
Change in EEG functional connectivity, specifically global efficiency, coherence, and phase-locking value at gamma frequency
Time frame: up to 2 hours after the intervention
electroencephalogram (EEG) oscillatory power
Change in the EEG power in alpha, delta, theta and beta bands
Time frame: up to 2 hours after the intervention
This study is completed, as verified in Mar 2026. You cannot join it, but the record below documents what was studied.
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