Alzheimer Disease, Cognitive Decline
Conditions
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.
Interventions
DEVICETranscranial 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.
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.
Sponsors
The National Brain Mapping Laboratory (NBML)
Technical University of Dortmund
Leibniz Research Centre for Working Environment and Human Factors
Institute for Research in Fundamental Sciences (IPM)
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
BASIC_SCIENCE
Masking
DOUBLE (Subject, Outcomes Assessor)
Eligibility
Sex/Gender
ALL
Age
50 Years to 85 Years
Healthy volunteers
Yes
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)
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Working Memory behavioral performance | 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. |
| electroencephalogram (EEG) oscillatory power | up to 2 hours after the intervention | Change in the EEG power in the gamma band |
| electroencephalogram (EEG) functional connectivity | up to 2 hours after the intervention | Change in EEG functional connectivity, specifically global efficiency, coherence, and phase-locking value at gamma frequency |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| electroencephalogram (EEG) oscillatory power | up to 2 hours after the intervention | Change in the EEG power in alpha, delta, theta and beta bands |
Countries
Iran
Outcome results
None listed