Nonjudgment Mediates the Effect of a Brief Smartphone-Delivered Mindfulness Intervention on Rumination in a Randomized Controlled Trial with Adolescents

Rumination, a risk factor for the development of psychopathology that often emerges during adolescence, has been successfully targeted in mindfulness interventions; however, the mechanism is unclear. Acquiring mindfulness skills may help reduce repetitive ruminative thinking and in turn alleviate negative emotions. The goal of the present study was to test whether changes in trait mindfulness accounted for the reductions in rumination following a brief mindfulness intervention.

Ruminative adolescents (n = 152; 59% girls, 18% racial/ethnic minority, mean age = 13.72, SD = 0.89) were randomly assigned to use a mobile app 3 times per day for 3 weeks that delivered brief mindfulness exercises or a mood monitoring only control. They completed questionnaires to assess rumination, mindfulness, and depression at baseline, post-intervention and follow-up at 6 weeks, 12 weeks, and 6 months post-intervention.

We ran a parallel causal mediation model with bootstrapping to examine whether changes in facets of mindfulness (Nonjudgment, Nonreactivity, Describe, Awareness, Observe) mediated the effect of treatment group on change in rumination. A significant indirect effect of Treatment Group on Rumination emerged through Nonjudgment. Next, we ran a serial mediation model predicting depressive symptoms during the follow-up period (12 weeks and 6 months post-intervention) from Treatment Group through Nonjudgment (immediate post-intervention) and rumination (at 6 weeks post-intervention). Results from this model were significant.

Our findings suggest that a brief mindfulness intervention increases nonjudgmental awareness, thereby reducing rumination and subsequent depressive symptoms. Understanding these mechanisms may help tailor interventions for at-risk youth.

This study was registered with Clinicaltrials.gov (Identifier NCT03900416).