Abstract
Anxiety-related attention bias (AB) is the preferential processing of threat observed in clinical and sub-clinical anxiety. Attention bias modification training (ABMT) is a computerized cognitive training technique designed to systematically direct attention away from threat and ameliorate AB, but mixed and null findings have highlighted gaps in our understanding of mechanisms underlying ABMT and how to design the most effective delivery systems. One neuromodulation technique, transcranial direct current stimulation (tDCS) across the pre-frontal cortex (PFC) may augment the effects of ABMT by strengthening top-down cognitive control processes, but the evidence base is limited and has not been generalized to current approaches in digital therapeutics, such as mobile applications. The present study was a single-blind randomized sham-controlled design. We tested whether tDCS across the PFC, vs. sham stimulation, effectively augments the beneficial effects of a gamified ABMT mobile app. Thirty-eight adults (Mage = 23.92, SD = 4.75; 18 females) evidencing low-to-moderate anxiety symptoms were randomly assigned to active or sham tDCS for 30-min while receiving ABMT via a mobile app. Participants reported on potential moderators of ABMT, including life stress and trait anxiety. ECG was recorded during a subsequent stressor to generate respiratory sinus arrhythmia (RSA) suppression as a metric of stress resilience. ABMT delivered via the app combined with tDCS (compared to sham) reduced AB and boosted stress resilience measured via RSA suppression, particularly for those reporting low life stress. Our results integrating tDCS with ABMT provide insight into the mechanisms of AB modulation and support ongoing evaluations of enhanced ABMT reliability and effectiveness via tDCS.
Highlights
Anxiety disorders are among the most common and costly of mental health conditions in the United States (Kessler et al, 2005), but only a fraction of patients seek treatment, and a third of those do not respond to current treatment options (Bystritsky, 2006)
Several models posit that anxiety-related attention bias (AB) may result from disruptions in the ability to recruit top-down attention control (e.g., MacLeod et al, 1986; Bishop et al, 2004; Cisler and Koster, 2010; Dennis-Tiwary et al, 2019), which would be signaled by reduced activation of the PFC, in particular the dorsal lateral PFC (DLPFC; Bishop, 2009; Browning et al, 2010)
We have recently demonstrated in two placebo-controlled studies with college students evidencing elevated trait anxiety that this user-friendly and engaging version of attention bias modification training (ABMT) reduced anxiety, stress reactivity, and AB in a single, lab-based session (Dennis and O’Toole, 2014; Dennis-Tiwary et al, 2016)
Summary
Anxiety disorders are among the most common and costly of mental health conditions in the United States (Kessler et al, 2005), but only a fraction of patients seek treatment, and a third of those do not respond to current treatment options (Bystritsky, 2006). A subsequent study (Heeren et al, 2015) selecting for high trait anxiety adults (who did not show AB at baseline), found that combining ABMT and tDCS reduced an eye tracking index of AB (duration of gaze fixated on threat) Another recent study focused on combining ABMT and tDCS among participants with alcohol dependence (den Uyl et al, 2018), no main effects or interactions on AB were found. In a placebo-controlled trial including pregnant women who used the app for 30–40 min a week for 1 month, stress reactivity measured via salivary cortisol and subjective anxiety were significantly reduced (Dennis-Tiwary et al, 2017) These data demonstrate that the app is an effective delivery system for ABMT. Individual differences in anxiety severity and life stress will be explored as potential moderators of effects
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