Testing the Efficacy of a Brief, Self-Guided Mindfulness Ecological Momentary Intervention on Emotion Regulation and Self-Compassion in Social Anxiety Disorder: Randomized Controlled Trial

Background: Theories propose that brief, mobile, self -guided mindfulness ecological momentary interventions (MEMIs) could enhance emotion regulation (ER) and self -compassion. Such changes are posited to be mechanisms of change. However, rigorous tests of these theories have not been conducted. Objective: In this assessor -blinded, parallel -group randomized controlled trial, we aimed to test these theories in social anxiety disorder (SAD). Methods: Participants with SAD (defined as having a prerandomization cut-off score >= 20 on the Social Phobia Inventory self -report) were randomized to a 14 -day fully self -guided MEMI (96/191, 50.3%) or self -monitoring app (95/191, 49.7%) arm. They completed web -based self -reports of 6 clinical outcome measures at prerandomization, 15 -day postintervention (administered the day after the intervention ended), and 1 -month follow-up time points. ER and self -compassion were assessed at preintervention and 7 -day midintervention time points. Multilevel modeling determined the efficacy of MEMI on ER and self -compassion domains from pretrial to midintervention time points. Bootstrapped parallel multilevel mediation analysis examined the mediating role of pretrial to midintervention ER and self -compassion domains on the efficacy of MEMI on 6 clinical outcomes. Results: Participants demonstrated strong compliance, with 78% (149/191) engaging in at least 80% of the MEMI and self -monitoring prompts. MEMI was more efficacious than the self -monitoring app in decreasing ER goal-directed behavior difficulties (between -group Cohen d =-0.24) and lack of emotional clarity (Cohen d =0.16) and increasing self -compassion social connectedness (Cohen d =0.19), nonidentification with emotions (Cohen d =0.16), and self -kindness (Cohen d =0.19) from pretrial to midintervention time points. The within -group effect sizes from pretrial to midintervention were larger in the MEMI arm than in the self -monitoring app arm (ER goal-directed behavior difficulties: Cohen d =-0.73 vs -0.29, lack of emotional clarity: Cohen d =-0.39 vs -0.21, self -compassion domains of social connectedness: Cohen d =0.45 vs 0.19, nonidentification with emotions: Cohen d =0.63 vs 0.48, and self -kindness: Cohen d =0.36 vs 0.10). Self -monitoring, but not MEMI, alleviated ER emotional awareness issues (between -group Cohen d =0.11 and within -group: Cohen d =-0.29 vs -0.13) and reduced self -compassion acknowledging shared human struggles (between -group Cohen d =0.26 and within -group: Cohen d =-0.23 vs 0.13). No ER and self -compassion domains were mediators of the effect of MEMI on SAD symptoms ( P =.07-<.99), generalized anxiety symptoms ( P =.16-.98), depression severity ( P =.20-.94), repetitive negative thinking ( P =.12-.96), and trait mindfulness ( P =.18-.99) from pretrial to postintervention time points. Similar nonsignificant mediation effects emerged for all of these clinical outcomes from pretrial to 1 -month follow-up time points ( P =.11-.98). Conclusions: Brief, fully self -guided, mobile MEMIs efficaciously increased specific self -compassion domains and decreased ER difficulties associated with goal pursuit and clarity of emotions from pretrial to midintervention time points. Higher -intensity MEMIs may be required to pinpoint the specific change mechanisms in ER and self -compassion domains of SAD. Trial Registration: Open Science Framework (OSF) Registries; osf.io/m3kxz https://osf.io/m3kxz