Background and Objective:
Schools are an ideal setting for promoting student mental health and well-being. This study aimed to evaluate the effectiveness of a school-based multi-component intervention on the mental health of adolescents.

Methods:
A clustered randomized controlled trial was employed in eight high schools in Dhaka city, Bangladesh, which were randomly assigned to either intervention or control group; 40 students in grades 8-9 (aged 13-16 years) from each school took part in the trial (n=160 per group). Students in the intervention schools participated in a 12-week multi-component physical activity intervention, developed using the WHOs Health-Promoting Schools framework. Control group schools continued their usual practice. Participants completed baseline and endline surveys measuring depressive symptoms (Centre for Epidemiologic Studies Depression Scale), and life satisfaction (Cantril ladder), along with other socio-demographic and behavioral characteristics. Linear mixed-effects modelling was used to evaluate the intervention effects.

Results:
Depressive symptoms in the intervention groups decreased by 41% at the post-intervention, while remaining stable in the control group. There was a 24% increase in life satisfaction in the intervention group while a 3% decrease in the control group. Multivariable modelling showed that students in the intervention group had significantly lower levels of depressive symptoms (β=-4.60, 95% CI: -5.76 to -3.46) and higher levels of life satisfaction (β=1.43, 95% CI: 0.77 to 2.10) compared to their counterparts in the control group. Sensitivity analyses supported the positive effects of the intervention.

Conclusions:
Our school-based multi-component intervention is effective in enhancing mental health indicators in school children. Future trials should be scaled-up to include schools in rural and regional settings and use robust measures of mental well-being.