Feasibility of Combining Transcranial Direct Current Stimulation and Active Fully Embodied Virtual Reality for Visual Height Intolerance: A Double-Blind Randomized Controlled Study

Abstract

Background: Transcranial Direct Current Stimulation (tDCS) and Virtual Reality Exposure Therapy (VRET) are individually increasingly used in psychiatric research. Objective/Hypothesis: Our study aimed to investigate the feasibility of combining tDCS and VRET with the features of wireless, 360° full immersion and embodiment and an active task to reduce height-induced anxiety. Methods: We carried out a pilot randomized, double-blind, controlled study associating VRET (two 20 min sessions with a 48 h interval, during which, participants had to cross a plank at rising heights in a building in construction) with online tDCS (targeting the ventromedial prefrontal cortex) with 28 participants. The primary outcomes were the sense of presence level and the tolerability. The secondary outcomes were the anxiety level (Subjective Unit of Discomfort) and the salivary cortisol concentration. Results: We confirmed the feasibility of the association between tDCS and fully embodied VRET associated with a good sense of presence without noticeable adverse effects. In both groups, a significant reduction in the fear of height was observed after two sessions, with only a small effect size of add-on tDCS (0.1) according to the SUD. The variations of cortisol concentration differed in the tDCS and sham groups. Conclusion: Our study confirmed the feasibility of the association between wireless online tDCS and active, fully embodied VRET. The optimal tDCS paradigm remains to be determined in this context to increase effect size and then adequately power future clinical studies assessing synergies between both techniques.

Virtual reality in the diagnostic and therapy for mental disorders: A systematic review

“…Another series of studies investigated whether VRET for acrophobia can be boosted by additional brain stimulation or pharmacological treatment. Regarding brain stimulation, one study (Herrmann et al, 2017) thereby reported an acceleration of VRET effects if the medial prefrontal cortex was stimulated by repetitive transcranial magnetic stimulation before VRET conduction, whereas another study (Bulteau et al, 2022) found no such acceleration effects after transcranial direct current stimulation of the ventromedial prefrontal cortex during VRET conduction. Regarding pharmacological treatment, in turn, some studies found no differences between VRET + pharmacological treatment and VRET + placebo treatment (Meyerbroeker, Morina, & Emmelkamp, 2018; Tart et al, 2013), whereas two controlled trials (de Quervain et al, 2011;Ressler et al, 2004) reported greater reduction of acrophobia after VRET + pharmacological treatment.…”

Anxiety as a disorder of uncertainty: implications for understanding maladaptive anxiety, anxious avoidance, and exposure therapy

“…Dcycloserine, a partial NMDA receptor antagonist with effects on fear conditioning, shows mixed results when used during exposure sessions; the number and timing of doses may moderate response (Hofmann, 2014;Mataix-Cols et al, 2017;Norberg et al, 2008) but targeted, pre-registered tests of proposed moderators failed to demonstrate an augmenting effect (e.g., Smits et al, 2020). Transcranial magnetic stimulation (TMS) or transcranial direct current stimulation (tDCS) to increase or decrease activity in learning-related cortical regions during exposure have not been consistently effective (Bulteau et al, 2022;Cobb et al, 2021;Isserles et al, 2021;Zaizar et al, 2021). Behavioral approaches that normatively enhance extinction, such as novelty-facilitated extinction (Dunsmoor et al, 2015), do not improve exposure therapy outcomes in people with anxiety (Steinman et al, 2022).…”