ATTEND: (Adolescents and carers using mindfulness Therapy To END depression)

Research question Can a novel intervention, Mindfulness for Adolescents and Carers (MAC), improve recovery among young people (15-18-years-old) with depression who have failed to completely respond to first line treatment or who have relapsed? Background The prevalence of depression among adolescents is high and has increased over the last 20-years.

Depression is associated with significant distress and impairment in adolescence, including school failure, self-harm, and substance misuse; and adolescent depression predicts worse mental and physical health outcomes, and occupational functioning, in adulthood. Current treatments for adolescent depression show modest effects.

This is problematic because treatment non-response and residual symptoms strongly predict recurrent depression, while each depressive episode increases the risk of subsequent recurrence. Effective methods to treat residual symptoms and prevent relapse are therefore critical. Among adults, Mindfulness Based Cognitive Therapy (MBCT) is the NICE-recommended treatment for recurrent depression.

A similar mindfulness-based intervention could be efficacious for depressed adolescents, but we currently lack evidence. We have adapted MBCT specifically for adolescents with depression.

Key features of our intervention include theory-driven targeting of maintenance factors and a parallel intervention for carers.

Aims and objectives We aim to evaluate the clinical- and cost-effectiveness of MAC drawing on hybrid effectiveness implementation trial methods.

Our objectives are to: deliver a training package for CAMHS professionals; build an App to support and measure mindfulness practices; run a multi-site RCT; test theoretically derived moderators and mediators; and develop an implementation plan and toolkit for later scale up.

Methods Work Package (WP) 1 will refine and deliver training for CAMHS practitioners to competently teach MAC; and co-produce with experts-by-experience an App to support and measure between-group mindfulness practices (WP2).

WP3 comprises a two-arm, pragmatic, parallel-group, superiority, individually randomised controlled hybrid type I clinical and cost-effectiveness trial of MAC plus Treatment as Usual (TAU) versus TAU alone, among N=480 15–18-year-olds who have received a previous evidence-based intervention for depression, and who continue to experience significant symptoms of depression.

WP3 will include modelling of life-time cost-effectiveness while WP4 will test potential moderators and mechanisms of action using new analytical approaches and qualitative methods.

WP5 will apply the Consolidated Framework for Implementation Research to collect and analyse implementation data (comprising surveys, interviews, fidelity assessments, and in-depth case studies) across all trial sites and WPs.

Timelines for delivery The programme will be delivered over 4-years; WP1 (training CAMHS practitioners) and WP2 (App development) will start immediately.

WP3 (RCT) will recruit from months 10 to 26 with final assessments at month 38, with an internal pilot and a Stop-Go checkpoint at month 19. WP4 (mechanisms of action) will run in parallel to WP3, while WP5 (implementation) runs throughout. Months 39-48 allow sufficient time for analysis, synthesis across WPs, dissemination and report-writing.

Anticipated impact and dissemination Impacts include knowledge generation and tangible outputs (eg App, implementation toolkit).

We will mobilize knowledge with our lived experience team via social media, podcasts, and blogs modified to suit the needs and interests of different stakeholders including service-users and practitioners.