Feasibility of Gamma Transcranial Alternating Current Stimulation to Reduce Beta-amyloid Load and Improve Memory

Study Overview
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Brief Summary
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This project assessed the feasibility of transcranial alternating current stimulation in the gamma band to lower beta-amyloid load and improve memory performance.

Detailed Description
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Thirteen individuals with aMCI received eight 60-minute sessions of 40-Hz (gamma) transcranial alternating current stimulation (tACS) in a single-arm design. Outcome measures were assessed pre- and post-intervention.

Official Title
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Feasibility of Gamma Transcranial Alternating Current Stimulation to Reduce Beta-amyloid Load and Improve Memory

Conditions
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Mild Cognitive Impairment

Intervention / Treatment
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* Device: Transcranial alternating current stimulation


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: English speaking Grade 12 or more education Normal or corrected to normal vision and hearing Ability to complete cognitive tasks Ability to cooperate and comply with all study procedures Ability to tolerate tACS Self-reported memory complaint Diagnosed with mild cognitive impairment Amyloid positive Exclusion Criteria: Neurological or psychiatric disorders other than mild cognitive impairment Receiving investigational medications or have participated in a trial with investigational medications within last 30 days Family history of epilepsy Implanted electronic devices (e.g., pacemaker) Prior head trauma Pregnant IQ < 80 Taking cholinesterase inhibitory, memantine, or psychotropic medication Taking anti-depressants or anti-anxiety medication Color blind Substance abuse Glaucoma Macular degeneration Amblyopia (lazy eye) Strabismus (crossed eyes)

Ages Eligible for Study
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Minimum Age: 55 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Gamma Stimulation Group<br>This group will receive gamma stimulation | Device: Transcranial alternating current stimulation<br>* Transcranial alternating current stimulation (tACS) will be applied at 40 Hz (gamma band) during eight sessions over the course of a month.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Side Effects | Side effects were measured on a scale from 0 (not noticable) to 10 (not tolerable): headache, neck pain, scalp pain, tingling, itching, burning sensation, increased sleepiness, trouble concentrating, acute mood change, and phosphenes. Average rating across all measures reported as indicator of side effects. | Average of all post-tACS sessions, up to 1 month | 
| Drop Out | Drop out rate will be assessed as the number of participants who withdraw or are withdrawn from the study. | post-tACS, up to 1 month | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Beta Amyloid Load Change | Change in plasma-based beta amyloid (AB) load was assessed as the AB42/40 ratio, calculated as post minus pre AB42/40 ratio. Greater increase is better. | pre-tACS (baseline) and post-tACS (1 month) | 
| Memory: Recall Change | Episodic memory was assessed pre and post intervention as the number of words correct during the short delay free recall portion of the California Verbal Learning Test. Change was assessed as post minus pre. Greater increase is better. | pre-tACS (baseline), post-tACS (after one month of treatment) | 
| Memory: Paired Associates Change | Episodic memory was assessed pre and post intervention from memory accuracy for a paired associates task for visual objects. Change was assessed post minus pre. Greater increase is better. | pre-tACS (baseline), post-tACS (after one month of treatment) | 
| Memory: Fluency Change | Episodic memory fluency was assessed pre and post intervention from performance on the FAS task. Unit of measurement is the number of words names starting with the letter f, a, or s. Change was calculated as post minus pre. Greater increase is better. | pre-tACS (baseline), post-tACS (after one month of treatment) | 
| Change in Tau | Plasma tau levels was assessed pre and post intervention. Change was calculated as post minus pre. Greater decrease is better. | pre-tACS (baseline), post-tACS (after one month of treatment) |