Mechanisms and Predictors of Change in App-Based Mindfulness Training for Adolescents

A growing body of research implicates rumination as being a transdiagnostic risk factor involved in the development of depression and anxiety in youth. Critically, mindfulness meditation has shown significant promise in targeting rumination, and ultimately improving depressive and anxiety symptoms. Mindfulness apps offer a convenient and cost-effective means for accessing mindfulness training, while being interactive and engaging for youth. Despite their growing popularity among teens, strikingly little research has been conducted on these apps. Two critical questions have yet to be addressed: (1) what are the underlying neural and cognitive mechanisms that account for the beneficial effects of these apps and (2) for whom is app-based mindfulness well-suited. To address these gaps, adolescents (ages 13-18) will be randomly assigned to an app-delivered mindfulness course vs. a control condition and will complete pre- and post-intervention resting state functional magnetic resonance imaging (fMRI) scans to probe static and dynamic functional connectivity within - and between - brain networks strongly implicated in mindfulness training and rumination. In addition, cognitive tasks will be administered at pre- and post-intervention to assess attentional control abilities putatively enhanced by mindfulness training. Finally, mindfulness skills and changes in rumination will be assessed via smartphone-based ecological momentary assessment (EMA). First, the investigators will test whether changes in (1) brain functional connectivity, (2) attentional control and (3) acquisition and use of mindfulness skills mediate between-group (i.e., app vs. control) differences in the reduction of rumination. Second, the investigators will test whether a machine learning model incorporating baseline clinical, demographic, and psychosocial characteristics can be used to identify which adolescents are predicted to benefit from app-based mindfulness training.

Inclusion Criteria: * Both genders, all ethnicities (see Section: Inclusion of Women and Minorities) * Ages 13-18 years * Written informed assent/consent from adolescent and parent/guardian * English as a first language or English fluency * Right-handed * Personal iPhone or Android smartphone * CRSQ rumination subscale score * If on psychotropic medication, must be on stable dose for at least 2 months Exclusion Criteria: * History or current diagnosis of any of the following DSM-5 disorders: schizophrenia spectrum or other psychotic disorder, bipolar disorder, substance/alcohol use disorder within the past 12 months or lifetime severe substance/alcohol use disorder. * Systemic medical or neurological illness that could impact fMRI measures of cerebral blood flow * Failure to meet standard exclusion criteria for fMRI scanning (e.g. pregnancy, claustrophobia, cardiac or neural pacemakers, surgically implanted metal devices, cochlear implants, metal objects in the body) * History of seizure disorder, or head trauma with loss of consciousness \> 2 mins * Serious or unstable medical illness (e.g., cardiovascular, hepatic, renal, respiratory, endocrine, neurologic or hematologic disease) * Participants with active suicidal ideation will be immediately referred to appropriate clinical treatment. * Current or past treatment with mindfulness-based psychotherapy (e.g., MBCT, DBT or ACT) * Exposure to in-person or app-based mindfulness/meditation course (at least 300 mins of past practice)