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.