Modulation of Fear Extinction Processes Using Transcranial Electrical Stimulation

Study Overview
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Brief Summary
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The aim of this study is to examine the effects of transcranial electrical stimulation on processes associated with fear extinction in healthy humans.

Detailed Description
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Research links the processes of fear conditioning and extinction to the treatment of anxiety and stress-related disorders. Moreover, considerable translational research examines the neural correlates of these processes. However, virtually no research in humans manipulates neural correlates of these processes, which limits basic-clinical integration. The present study aimed to use transcranial electrical stimulation (tES) to modulate processes associated with fear extinction in order to assess the potential utility of tES in enhancing exposure-based treatment. To this end, healthy participants underwent a three-day fear conditioning and extinction paradigm. Participants were randomly assigned into 3 groups, differing in terms of tES applied during the extinction learning phase (Day 2) and targeting the medial prefrontal cortex: 1) direct current (DC) stimulation, aimed at enhancing extinction learning; 2) alternate current (AC) stimulation, aimed at interfering with reconsolidation of the fear memory activated during the extinction phase; and 3) sham stimulation. The outcome measures (outlined next) involve the assessment of extinction recall during a test phase (Day 3). Successful modulation of extinction learning by tES would be reflected in enhanced extinction recall.

Official Title
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Modulation of Fear Extinction Processes Using Transcranial Electrical Stimulation

Conditions
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Stress Related Disorder, Anxiety

Intervention / Treatment
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* Device: Sham stimulation (1.5 milliampere,30 seconds)
* Device: DC stimulation (1.5 milliampere, 20 minutes)
* Device: AC stimulation (1.5 milliampere,1.5 Hertz frequency)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Exclusion Criteria: Self-reported major psychiatric condition Screening specific for electrical stimulation (psychotropic medication, metal implants in head, epilepsy or seizure history)

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 50 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: Basic Science
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Sham Comparator: Sham<br>Sham electrical stimulation | Device: Sham stimulation (1.5 milliampere,30 seconds)<br> <br> * Other names: DC Stimulator Plus (neuroConn, Germany), serial 0118;|
| Experimental: DC: Direct current<br>Direct current electrical stimulation | Device: DC stimulation (1.5 milliampere, 20 minutes)<br> <br> * Other names: DC Stimulator Plus (neuroConn, Germany), serial 0118;|
| Experimental: AC: Alternating current<br>Alternating current electrical stimulation | Device: AC stimulation (1.5 milliampere,1.5 Hertz frequency)<br> <br> * Other names: DC Stimulator Plus (neuroConn, Germany), serial 0118;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Galvanic Skin Response (GSR) | GSR was measured throughout the task using 2 standard electrodes on the fingers. Measurement units were in micro-Siemens; scores were square-root-transformed (a common method in GSR studies). A higher level of GSR in response to stimuli is taken to reflect greater physiological fear response, and thus worse in the context of the relevance of the study conditions to the treatment of anxiety disorders. Scores were collected in response to presentation of the CS+ (the stimulus conditioned to be associated with an aversive outcome) and the CS- (the stimulus not conditioned to be associated with any outcome). | During three-day experimental task | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Self-reported Fear Rankings | Participants marked how fearful they are of stimuli used in the task on a single 10-point scale (1=not afraid, 10=extremely afraid). Higher scores therefore reflect greater fear and are worse in the context of treatment for anxiety disorders. Scores were collected in response to presentation of the CS+ (the stimulus conditioned to be associated with an aversive outcome) and the CS- (the stimulus not conditioned to be associated with any outcome). | During three-day experimental task |