The efficacy of an online self-administered single session intervention to promote growth mindset in adolescents: A randomised controlled trial

Background: Single-session interventions (SSIs) are emerging as one promising way to support one's mental health. Growth mindset refers to the beliefs about the malleability of traits and attributes. Building upon a feasibility study of a growth mindset single session intervention, this randomised controlled trial aimed to evaluate its efficacy when delivered online to young people. Methods: We recruited participants aged 14–18-year-olds via social media, schools, and charities in the UK. They were randomised to receive either an online video-based intervention or were placed on a waitlist control. They reported anxiety and depression symptoms, as well as personality mindset and psychological flexibility at baseline and at 1-month follow up. An intention-to-treat (ITT) analysis and a case completer analysis were conducted. Results: In a sample of 104 participants (mean age = 16.3), an ITT analysis yielded negligible effects on anxiety and depression symptoms (d = 0.07, 95% CI: [−0.32, 0.47]) and psychological flexibility (d = −0.12, 95% CI: [−0.50, 0.25]) at 4-week follow-up. The personality mindset measure yielded a significant large effect relative to waitlist (d = −0.96, 95% CI: [−1.87, −0.04], p = 0.02), however it was statistically non-significant with Bonferroni correction. Case completer analysis resulted in similar observations. Conclusion: The intervention impacted personality mindset but had limited effect on anxiety and depression. Large sample sizes, improve retention rate, and a longer follow-up period are needed in future studies.