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Completed

NCT Number: NCT06740864

40 Hz Transcranial Alternating Current Stimulation for Inducing Gamma Oscillations

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.

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Key information

Conditions

Alzheimer Disease Brain Diseases Central Nervous System Diseases Cognition Disorders Cognitive Decline Cognitive Dysfunction Dementia Mental Disorders Nervous System Diseases Neurocognitive Disorders Neurodegenerative Diseases Tauopathies

Age range

50 year–85 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Institute for Research in Fundamental Sciences

Tehran, Iran

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • 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

Exclusion criteria

  • 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)

Treatment and study plan

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.

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.

Primary outcomes

  1. Working Memory behavioral performance

    Time frame: During procedure (20 minutes)

    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.

  2. electroencephalogram (EEG) oscillatory power

    Time frame: up to 2 hours after the intervention

    Change in the EEG power in the gamma band

  3. electroencephalogram (EEG) functional connectivity

    Time frame: up to 2 hours after the intervention

    Change in EEG functional connectivity, specifically global efficiency, coherence, and phase-locking value at gamma frequency

Secondary outcomes

  1. electroencephalogram (EEG) oscillatory power

    Time frame: up to 2 hours after the intervention

    Change in the EEG power in alpha, delta, theta and beta bands

Sponsors and collaborators

Lead sponsor

The National Brain Mapping Laboratory (NBML)

Other

Collaborators

  • Institute for Research in Fundamental Sciences (IPM)
  • Leibniz Research Centre for Working Environment and Human Factors
  • Technical University of Dortmund

Registry information

Official study title

Induction and Stabilization of Gamma Oscillations With 40 Hz Transcranial Alternating Current Stimulation in Healthy Elderly

Important dates

Study start
2024
Primary completion
2025
Study completion
2025
First posted
Dec 18, 2024
Registry last updated
Mar 18, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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