40 Hz Transcranial Alternating Current Stimulation for Inducing Gamma Oscillations

NCT06740864 | Completed

• 1 other identifier: IfADo_196_P3
• Study Type: interventional
• Target: 30
• Locations: 1 country
• Sites: 1

Brief Summary

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.

Conditions

Alzheimer Disease; Cognitive Decline

Outcome Measures

Primary Outcomes (3)

• 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.

  During procedure (20 minutes)

• electroencephalogram (EEG) oscillatory power

  Change in the EEG power in the gamma band

  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

  up to 2 hours after the intervention

Secondary Outcomes (1)

• electroencephalogram (EEG) oscillatory power

  up to 2 hours after the intervention

Study Arms (3)

40 Hz prefrontal Transcranial alternating current stimulation

ACTIVE COMPARATOR

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

40 Hz frontal-temporal Transcranial alternating current stimulation

ACTIVE COMPARATOR

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

sham Transcranial alternating current stimulation

SHAM COMPARATOR

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

Interventions

Transcranial alternating current stimulation DEVICE

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.

40 Hz prefrontal Transcranial alternating current stimulation

Sham Transcranial alternating current stimulation DEVICE

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.

sham Transcranial alternating current stimulation

Eligibility Criteria

• Age: 50 Years - 85 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• healthy elderly between 50-80 years of age
• normal or corrected to normal eye vision
• right-handed
• non-smokers
• at least 70 % accuracy in working memory training task

You may not qualify if:

• history of neurological or psychiatric disorders including seizures or epilepsy,
• Taking CNS, blood pressure and other medications
• having metal implants in the head and neck
• significant cognitive decline meassured by The Montreal Cognitive Assessment (MoCA)

Sponsors & Collaborators

• The National Brain Mapping Laboratory (NBML): lead
• Technical University of Dortmund: collaborator
• Leibniz Research Centre for Working Environment and Human Factors: collaborator
• Institute for Research in Fundamental Sciences (IPM): collaborator

Study Sites (1)

Institute for Research in Fundamental Sciences

Tehran, Iran

Location

MeSH Terms

Conditions

Alzheimer Disease; Cognitive Dysfunction

Interventions

Transcranial Direct Current Stimulation

Condition Hierarchy (Ancestors)

Dementia; Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Tauopathies; Neurodegenerative Diseases; Neurocognitive Disorders; Mental Disorders; Cognition Disorders

Intervention Hierarchy (Ancestors)

Electric Stimulation Therapy; Therapeutics; Convulsive Therapy; Psychiatric Somatic Therapies; Behavioral Disciplines and Activities; Electroshock; Psychological Techniques

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: DOUBLE
• Who Masked: PARTICIPANT, OUTCOMES ASSESSOR
• Purpose: BASIC SCIENCE
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Principal Investigator

Study Record Dates

• First Submitted: December 14, 2024
• First Posted: December 18, 2024
• Study Start: June 1, 2024
• Primary Completion: February 1, 2025
• Study Completion: June 1, 2025
• Last Updated: March 18, 2026

Record last verified: 2026-03

Locations

IR (1)