This double-blind randomized controlled clinical trial aims to test whether transcranial direct current stimulation (tDCS) can be used to modulate fear extinction learning during exposure therapy for pathological fear, including fear of spiders, snakes, or germs / contamination. Participation takes place over three laboratory visits, including (1) a pre-treatment visit, (2) a treatment and post-treatment visit, and (3) a 1 month follow-up visit. During treatment, participants will receive either 20 minutes of active or sham tDCS, followed by 30 minutes of in vivo exposure therapy.
In a trans-diagnostic sample with marked pathological fear and behavioral avoidance, this study aims to: (1) evaluate whether excitatory tDCS of the mPFC and inhibitory tDCS of right dlPFC enhances exposure therapy relative to sham tDCS; (2) determine whether tDCS effects are moderated by baseline negative prognostic indicators; and (3) determine whether tDCS effects are mediated by pre-post changes in vigilance to threat, in-session fear reduction, and contextual memory for the exposure context. If successful, the project may discover a potentially effective exposure therapy augmentation, and may enhance knowledge of the behavioral, cognitive, affective, and neurobiological factors that moderate and mediate acute treatment response and maintenance of treatment gains. This knowledge may inform treatment development efforts for more debilitating forms of pathological fear.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
QUADRUPLE
Enrollment
49
Participants will receive 20 minutes of either active or sham tDCS prior to in vivo exposure to feared targets.
Participants will receive 30 minutes of in vivo exposure to feared targets following either active or sham tDCS
Laboratory for the Study of Anxiety Disorders
Austin, Texas, United States
Change in peak fear during two behavioral approach tasks across time-points.
Subjective units of distress from 0 = no fear, to 100 = extreme fear
Time frame: Pre-treatment (baseline), post-treatment (1 week later), and follow-up (1 month after treatment)
Change in approach level during two behavioral approach tasks across time points.
Highest difficulty level achieved from 0 = least challenging to 10 = most challenging.
Time frame: Pre-treatment (baseline), post-treatment (1 week later), and follow-up (1 month after treatment)
Change in arachnophobia symptom severity across time-points
Total score on the Fear of Spiders Questionnaire
Time frame: Pre-treatment (baseline), post-treatment (1 week later), and follow-up (1 month after treatment)
Change in ophidophobia symptom severity across time-points
Total score on the Fear of Snakes Questionnaire
Time frame: Pre-treatment (baseline), post-treatment (1 week later), and follow-up (1 month after treatment)
Change in germaphobia / contamination fear symptom severity across time points.
Total score on the Obsessive Compulsive Inventory - Revised.
Time frame: Pre-treatment (baseline), post-treatment (1 week later), and follow-up (1 month after treatment)
Threat vigilance task
Computer-based task that assesses attention biases towards and away from threatening images.
Time frame: Before and after tDCS administration (1 week after baseline)
Visuospatial working memory task
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Delayed match to sample task assessing recognition of 4 x 4 arrays of colored blocks, after a brief delay.
Time frame: Before and after tDCS administration (1 week after baseline)
Incidental contextual memory task
Assessment of incidental memory for a 4 x 4 array of line drawings from the Test of Memory Malingering, presented in the treatment context only during in vivo exposure.
Time frame: Stimulus presented during in vivo exposure (1 week after baseline), and memory assessed at follow-up (1 month after treatment)