The Effects of Alpha Stimulation on Induced Anxiety

December 2015

By Nolan Hill

ABSTRACT
Anxiety is defined as an emotional and physical reaction that prepares us to confront a feared stimulus. Among the many measureable changes induced by anxiety are changes in facial electromyography (EMG), heart rate (HR), and sweat gland activity (EDG). At a pathological level anxiety interferes with cognitive processes. Currently, when anxiety crosses into the pathological level, it is treated with a variety of therapies that share in their use of periods of exposure to anxiety-inducing stimuli. Several devices have been developed to alter brain activity by transcranial electrical stimulation (TCES).

One such device, Alpha-Stim®, has been shown to reduce anxiety in clinical samples. This suggests that the device might be useful in therapeutic exposure sessions, though no research to date has examined its use in such settings. In a double-blind, placebo controlled study participants were exposed to stimuli derived from the International Affective Picture System (IAPS) database that were chosen for their ability to elicit anxiety. A repeated measures analysis of variance was performed on recorded physiological data (EDG, HR, EMG) and subjective experience of anxiety as measured with Subjective Units of Distress Scale. Analysis of subjective units of distress scores showed that repeated exposure to anxiety eliciting pictures produced decreasing levels of distress over time (F (1,13) = 5.831, p = .031). EDG analysis revealed no statistically significant results. HR analysis revealed that TCES produced lower heart rates throughout the exposure (main effect of treatment; F (1,12) = 120.907 p < .001), and a trend toward increased heart rate during the exposure (treatment by time interaction; F (1,12) = 3.514, p = .085). Frontalis EMG analysis revealed a trend for the treatment groups to differ in their experience of negative emotional valence over the course of the exposure (F (1,12) = 3.209, p = .098).

Transcranial Electrical Stimulation
The Present Study
Design
Participants
Measurements- State Trait Anxiety Inventory, Subjective Units of Distress (SUDS)
International Affective Picture System (IAPS)
Skin Conductance,
Heart Rate
Frontalis Electromyogram

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