Quantifying tACS-driven Improvement of Working Memory in Depression

Study Overview
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Brief Summary
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TACS is an emergent method of non-invasive neuromodulation which can engage frequency-specific brain oscillations. It is increasingly recognized that neural oscillations play a system-organizing role in the brain. Evidence suggests that disorganized neural oscillations may also influence functionality of cognitive processes such as working memory. Thus, as TACS can affect neural oscillatory activity in the human brain in a non-invasive manner, it has promise to transform mental health care. The premise of this proposed work is that tACS concurrent with multi-session working memory (WM) focused skills will facilitate durable working memory and stabilized neural oscillations. Depression offers an excellent model to study the effects of tACS. The study seeka to administer 2mA of tACS using theta oscillations to improve working memory concerns associated with depression. The purpose of this study is to investigate the electrophysiological and behavioral effects of transcranial alternating current stimulation (tACS) in humans and to explore specific improvements in working memory and depressive symptoms. This study is placebo-controlled study. Participants will undergo pre- and post-assessments and either theta or sham tACS for 5 days. During each session, the volunteer will perform cognitive tasks while receiving tACS. Assessment sessions will include cognitive tasks, questionnaires, a clinical interview, and EEG.

Official Title
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Quantifying tACS-driven Improvement of Working Memory in Depression

Conditions
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Depression

Intervention / Treatment
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* Other: theta tACS stimulation
* Other: sham tACS stimulation


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age between 18 and 60 years old. Stated willingness to participate and comply with all study procedures. Stated availability for the duration of the study. Meet criteria for Major Depressive Disorder. Agreement to adhere to lifestyle considerations throughout study duration. No conflict of interest with the Department of Biomedical Engineering at the University of Minnesota. Confident level of English language. Exclusion Criteria: History or evidence of chronic neurological disorder (e.g., history of seizures, epilepsy, unexplained episodes of loss of consciousness, serious brain injury, severe or frequent headaches) Metal or electric implant in the head, neck or chest area. Implanted pacemakers or other electrically, magnetically, ir mechanically activated implant Vascular clips or other electrically sensitive support systems in the brain Serious health conditions (e.g., congestive heart failure pulmonary obstructive chronic disease, active neoplasia) History of head injuries. Pregnancy or breast-feeding. Significant damage of skin at sites of stimulation or other skin concerns, such as dermatitis, psoriasis, or eczema Alcohol or drug addiction. Any legal reason why the candidate cannot participate. Concurrent enrollment in another scientific or clinical study. Estimated IQ is below 70, defined by the WTAR. Active suicidality or other non-controlled neuropsychiatric illness. Active suicidality will be excluded based on a C-SSRS score of 3 or above in the last 6 months. Severe depression is defined as a PHQ-9 score above 20, which will also be excluded. A lifetime suicide attempt.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 60 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Supportive Care
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Sham Comparator: control group<br>participants with depressive disorder | Other: sham tACS stimulation<br>* A placebo control stimulation will use an identical montage to the stimulation montage. However, polarities of the electrodes will be such that only a minimal amount of current reaches the brain, which is achieved through controlled current shunting between neighboring electrodes. This so-called ActiSham protocol is a verified method to imitate the sensations of actual tACS, with minimal stimulation of the brain .<br>|
| Experimental: Active group<br>participants with depressive disorder | Other: theta tACS stimulation<br>* The low intensity transcranial electrical stimulation will be administered with a battery-powered, current-controlled, multi-channel stimulator from Neuroelectrics® Starstim 8. This device comes with a neoprene headcap to hold the electrodes in place. TACS will be delivered concurrently with the task. The multichannel, current-driven stimulator (Neuroelectrics StarStim 8) will be used to control independent stimulation electrodes on the scalp of the volunteer. The stimulation intensity will be up to 2 mA.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| working memory skills | Using a cognitive task that will consist of test responses (correct / incorrect) and reaction time (in ms). The task will include looking at faces expressing different emotions and matching them with previous images. | Day 5 | 
| Resting state EEG | examine theta power and connectivity with the EEG recordings | Day 6 | 
| Resting state EEG | examine theta power and connectivity with the EEG recordings | Day 35 | 
| task-based EEG | examine theta power and connectivity with the EEG recordings | Day 6 | 
| task-based EEG | examine theta power and connectivity with the EEG recordings | Day 35 |