Mental Health

The Preliminary Efficacy and Feasibility of SMILE Serious Game for Adolescents and Young Adults: Protocol for Cluster Randomized Multisite Adaptive Trial Design.

TL;DR

This protocol describes a cluster-randomized, multisite, multiarm adaptive proof-of-concept trial across 7 European countries to evaluate the acceptability, feasibility, reach, and preliminary efficacy of a CBT-informed gamified mobile intervention (SMILE) for adolescents and young adults aged 10-24 years.

Key Findings

The SMILE trial uses a cluster-randomized multisite multiarm adaptive proof-of-concept design across 7 European countries.

  • Participants are adolescents and young adults aged 10-24 years.
  • Recruitment occurs primarily through schools, universities, and community channels.
  • The target sample size is 1,438 participants.
  • The trial was prospectively registered on April 29, 2025 (ISRCTN32523126).
  • Study rollout is taking place from September 2025 to June 2026, with primary results expected in September 2026.

The intervention consists of two components: the SMILE Game App and a Companion App delivering CBT-based gamified content.

  • The SMILE Game App was developed by Nurogames and DigitalTwin Technology.
  • The Companion App was developed by RDIUP.
  • Content includes CBT-based gamified material, self-monitoring, and experience sampling.
  • One study condition includes automated personalized feedback, and one does not.
  • The intervention is informed by cognitive behavioral therapy (CBT) principles.

Clusters are assigned to one of three sequences comprising a neutral baseline period followed by varying numbers of game modules.

  • The three sequences consist of a neutral baseline period followed by 2, 4, or 5 game modules, respectively.
  • Clusters are randomized to either a feedback or no-feedback version of the intervention.
  • This adaptive design allows for interim analyses during the trial.
  • Quantitative data will be analyzed using linear mixed-effects models with adaptive interim analyses.

Primary outcomes of the trial are anxiety and depression, with multiple secondary outcomes also assessed.

  • Secondary outcomes include well-being, resilience, emotion regulation, self-efficacy, and social anxiety.
  • Feasibility, acceptability, engagement, app usage, in-game metrics, and diary-based digital markers are also assessed.
  • The trial aims to explore mechanisms of change and the impact of implementation contexts.
  • The design is described as a 'proof-of-concept' trial intended to inform a future definitive randomized controlled trial.

A mixed-methods realist evaluation framework is employed, combining quantitative trial data with qualitative stakeholder interviews.

  • Semistructured stakeholder interviews are conducted with young people, their legal guardians, school professionals, and clinicians.
  • Qualitative data will be analyzed using inductive thematic analysis within a mixed-methods realist evaluation framework.
  • The qualitative component aims to explore mechanisms of change and implementation context impacts.
  • This approach is intended to complement the quantitative cluster-randomized trial component.

As of March 2026, recruitment is ongoing with two study sequences completed and the third sequence beginning at the end of March 2026.

  • The trial began rollout in September 2025.
  • Two of the three study sequences had been completed as of March 2026.
  • The third sequence began at the end of March 2026.
  • Primary results are expected in September 2026.

The SMILE project is designed to address a gap in evidence for feasibility and preliminary efficacy of digital mental health interventions across diverse European settings.

  • Mental health problems frequently emerge during adolescence and young adulthood, yet many young people do not seek or receive timely support.
  • Evidence for feasibility and preliminary efficacy of serious games and gamified tools 'across diverse European settings remains limited.'
  • The findings are intended to inform intervention refinement and evaluation of the added value of personalized feedback.
  • Results will also inform the design of a future definitive randomized controlled trial and broader implementation in educational and clinical settings.

What This Means

This paper describes the design and protocol for a study called SMILE (Supporting Mental Health in Young People), which is testing a smartphone-based game designed to help young people aged 10-24 manage anxiety and depression. The game is based on cognitive behavioral therapy (CBT) — a well-established psychological approach — and is being tested across seven European countries in schools, universities, and community settings. The study involves nearly 1,500 young participants who are assigned to play different amounts of the game, with some also receiving automated personalized feedback on their progress. Researchers are measuring whether the game reduces anxiety and depression, as well as its effects on well-being, resilience, and emotion regulation. This research suggests that serious games and gamified apps could be a promising way to reach young people who might not otherwise seek mental health support, since they are accessible, engaging, and do not require a clinical appointment. The study is designed not just to measure whether the intervention works, but also to understand how and why it works — or doesn't — in different real-world settings. Interviews with young people, parents, school staff, and clinicians are being conducted alongside the trial to capture these contextual factors. The SMILE trial is a 'proof-of-concept' study, meaning its purpose is to gather early evidence to guide the development of a larger, more definitive trial. If the results show the game is feasible, acceptable, and shows signs of reducing mental health difficulties, the next step would be a full-scale randomized controlled trial. Primary results are expected in September 2026, and findings could inform how gamified mental health tools are incorporated into schools and healthcare settings across Europe.

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Citation

Smoktunowicz E, Maciejewski J, Lesnierowska M, Pietrzak M, Großwendt F, Mayer G, et al.. (2026). The Preliminary Efficacy and Feasibility of SMILE Serious Game for Adolescents and Young Adults: Protocol for Cluster Randomized Multisite Adaptive Trial Design.. JMIR research protocols. https://doi.org/10.2196/96292