The online mindset intervention ‘The Growth Factory’ for adolescents with intellectual disabilities: moderators and mediators

BACKGROUND: The online mindset intervention The Growth Factory (TGF) has shown promising effects—increasing growth mindsets and perseverance and decreasing mental health problems among youth with intellectual disabilities (ID). Studying moderators and mediators of intervention effects is essential to elucidate for whom and why TGF works. Using a randomised controlled trial design, we examined youth's baseline mindset, gender, age, level of ID and intervention satisfaction as moderators of TGF effects and examined whether the intervention effects of TGF on improvements in mental health were mediated by perseverance. METHODS: The sample consisted of 119 participants with mild to borderline ID (M ( age ) = 15.83; SD = 2.23), randomly assigned to the intervention (n = 60) or passive control group (n = 59). Participants reported mindsets, perseverance, internalising, externalising, attention and total mental health problems at pre‐test, at post‐test and at 3‐month follow‐up. Additionally, youth in the intervention group graded their satisfaction with a score at the end of each session. RESULTS: Findings indicated that the effectiveness of TGF was not affected by participants' baseline mindsets, age and ID level. TGF was more effective in reducing internalising problems in girls and increasing perseverance in boys. In addition, in the intervention group TGF was more effective in improving internalising, externalising and total mental health problems for youth who reported higher levels of intervention satisfaction at post‐test. Finally, TGF indirectly decreased internalising and externalising problems at follow‐up through improvements in perseverance reported at post‐test. CONCLUSIONS: TGF offers a universal, ‘add‐on’ mindset intervention complementing usual care programmes. It improves mindsets, perseverance and mental health in youth with ID. Both practical and theoretical implications are discussed.