Despite considerable evidence for the efficacy of psychological interventions for anxiety and depression in children and young people (CYP) (James et al. 2015; Goodyer, 2017) a significant proportion of CYP fail to access such treatments (Children's Commissioner for England 2016). Reasons for this implementation gap are many but include lack of accessibility to Child and Adolescent Mental Health Services (CAMHS) which are operating with long waiting times, high symptom thresholds and constraints in terms of what they are able to offer (Murphy and Fonagy, 2013). In order to reduce the need to access gap, particularly for young people experiencing symptoms of anxiety and depression but whom may not reach service thresholds, there is a need for the development of novel interventions which are cost-effective and can be disseminated at scale (Milat, King, Bauman, & Redman, 2012; Kazdin 2019). Single session interventions (SSI), particularly those which can be completed without therapist guidance, offer a scalable solution and have been found to be effective for a range of psychological difficulties in CYP (Schleider & Weisz 2017). One such SSI targets the implicit beliefs CYP hold about the malleability of their personality (known as their 'mindset') and has been found to reduce adolescent depressive symptoms and parent-reported anxiety over a 9-month period, relative to an active control condition (Schleider and Weisz, 2018). Investigation into trajectories of change found that changes in anxiety and depression were predicted by immediately post intervention changes in perceived primary and secondary control, indicating a potential underlying mechanism. Replication of these findings, along with exploration of predictors of treatment response and diverse opportunities for implementation is required and is the aim of the present study.~This study will test whether an online, self-administered, growth mindset SSI increases perceived primary and secondary control and reduces symptoms of anxiety and depression in children and adolescents aged between 8 and 16, relative to an active supportive therapy control condition. Outcome measures will be completed immediately post intervention. A secondary aim for the study will be to investigate the role of parental symptoms of anxiety or low mood as a potential moderator of treatment outcome. In order to achieve these aims, CYP and their parents or caregivers will be recruited through online advertisements, charities and schools.
The present study aims to evaluate whether an online, self-administered, single session intervention (SSI) increases children and adolescents' perceptions of control over external threats and their emotional experience and reduces self-reported symptoms of anxiety and low mood. Children and adolescents, identified by their parents as having difficulties with low mood or anxiety, will be randomised to receive either the growth mindset of personality intervention or an active comparison condition. Whether parental low mood and anxiety has a moderating impact on outcomes will also be investigated.