Major depression (MD) in youth is a serious psychiatric illness with extensive morbidity and mortality. The American Academy of Pediatrics recently released practice guidelines promoting primary care (PC)-based youth MD screening; however, even when diagnosed by PC providers, <50% of youth with MD access treatment. Thus, a need exists for interventions that are feasible for youths and parents to access and complete-and that may strengthen parents' likelihood of pursuing longer-term services. Single-session interventions (SSIs) may help forward these goals. SSIs include elements of comprehensive treatments, but their brevity makes them easier to disseminate at scale. Meta-analytic evidence suggests SSIs can reduce youth psychopathology, including self-administered (e.g., online) SSIs. One computer-based SSI, teaching growth mindset (GM; viewing personal traits as malleable), has reduced adolescent depressive symptoms in multiple RCTs. A second computer-based SSI was recently developed to reduce youth depressive symptoms via targeting reductions in self-hate-a symptom identified as important for the maintenance of other depressive symptoms in teenagers. This study will test whether either the growth mindset SSI (GM-SSI), the self-kindness SSI (SK-SSI), or both SSIs reduce symptoms of depression in adolescents, relative to an active "supportive therapy" SSI, which teaches adolescents to share their emotions with trusted others. Youths participating in existing research through the Healthy Brain Network (N=501) will receive either the growth mindset SSI (GM-SSI), the self-kindness SSI (SK-SSI), or the supportive therapy SSI (ST-SSI). The investigators will examine whether the GM-SSI and/or the SK-SSI, versus the ST-SSI will reduce youth depressive symptoms across three months. Results may identify two novel, potent, and brief interventions for adolescent depressive symptoms.

Major depression (MD) is the leading cause of disability in youth, with a global economic burden of >$210 billion annually (Whiteford et al., 2013). However, up to 70% of youth with MD do not receive services (Vitiello et al., 2011). Even among those who do access treatment, 30-65% fail to respond (March et al, 2007), demonstrating a significant need for more potent, accessible interventions for adolescent depressive symptoms and disorders.

The goal of this project is to assess the acceptability and effectiveness of two computerized, single-session interventions that may reduce depressive symptoms in adolescents. Single-session interventions (SSIs) have shown promise in preventing and reducing youth mental health problems (see Schleider & Weisz, 2017, for a meta-analysis). The present trial will be the first to evaluate the effectiveness of two distinct SSIs, targeting different types of depressive symptoms, in comparison to an active, previously-established comparison intervention.

The first SSI is designed to instill a growth mindset in youth: the belief that personal behaviors and characteristics, such as depressive symptoms, are malleable rather than fixed (Schleider, Abel, & Weisz, 2015). In previous trial, a single-session growth mindset intervention significantly reduced depressive symptoms in high symptom-adolescents (Schleider & Weisz, 2018); however, questions still remain about the benefits of this intervention across all adolescents.

The second SSI, which has not been tested previously, is designed to strengthen self-kindness and reduce self-hate. This SSI targets self-hate because it is a symptom of depression that has been identified as especially "central," or more important to the maintenance of other kinds of depressive symptoms, in adolescents at-risk for emotional difficulties. Because self-hate is an especially central symptom, an SSI that systematically, precisely reduces it may serve as an especially potent intervention.

This study will test whether either the growth mindset SSI (GM-SSI), the self-kindness SSI (SK-SSI), or both reduces symptoms of depression in adolescents, relative to an active "supportive therapy" SSI, which teaches adolescents to share their emotions with trusted others (Schleider & Weisz 2018). Our second goal is to evaluate whether the GM-SSI and SK-SSI target and specifically improve proximal targets, unique to each SSI, immediately after SSI administration, relative to the comparison intervention (e.g., whether the GM-SSI improves perceived control relative to the comparison intervention, and whether the SK-SSI alters fear of self-compassion relative to the comparison intervention). To test these possibilities, adolescents recruited from the Healthy Brain Network research study (Advarra Pro00012309) (N=501, 167 per SSI condition; ages 11-17) will be randomized to one of three intervention conditions: the web-based GM-SSI; the web-based SK-SSI; or the web-based, supportive therapy (control) SSI, which has been validated previously (Schleider & Weisz, 2016; Schleider & Weisz, 2018). Adolescents will report on their depression symptoms, perceived control, self-compassion, and related domains of functioning at pre-intervention, post-intervention, and at three-month follow-up. The investigators predict the growth mindset and self-kindness web-based interventions will both lead to larger reductions in adolescent depression symptoms relative to the control intervention. Additionally, the investigators predict that the growth mindset SSI will lead to larger reductions in perceived control than the supportive therapy intervention, and that the self-kindness SSI will lead to larger reductions in fear of self-compassion relative to the control program. Results may identify two novel, potent, and brief interventions for adolescent depressive symptoms.

Inclusion Criteria:

• Healthy Brain Network study participants
• Between the ages of 11-17 (inclusive)
• Fluent in English

Exclusion Criteria:

• Youth with parent-reported intellectual disability

De-identified individual-level participant data will be made publicly available in two databases: (1) COllaborative Informatics and Neuroimaging Suite (COINS), a HIPAA-compliant, open-source information system; (2) Longitudinal Online Research and Imaging System (LORIS), a HIPAA-compliant, web-based data and project management software. IPD associated with this project will be released to project collaborators upon the completion of the study (October 31, 2020). IPD associated with this project will be released to outside researchers at the next Healthy Brain Network quarterly data-release after the study's completion on October 31, 2020.

Protocol is outlined in this ClinicalTrials pre-registration. Statistical analysis plan will be uploaded to Open Science Framework prior to the study's onset October 31, 2019.

Study protocol information is publicly available on clinicaltrials.gov. Statistical analysis plan will be made publicly available on Open Science Framework. IPD will be made publicly available on COINS and LORIS, and access to these databases requires a data usage agreement signed by the institution using the data.

Neither investigators, outcomes assessor, youth, nor parents will know the condition assigned to the youth.