In a large, 3 year long-term follow up study by Johan Åhlén, Ata Ghaderi and me, we did not find any long-term effects of a school-based intervention aimed to prevent anxiety and depression symptoms. The study included 695 children 8–11 years old from 17 schools in Sweden. The kids were either randomized to the prevention intervention or a control condition. According to the attrition analyses, the effect (or lack thereof) may have been biased towards a null-result.

The prevention intervention that was used in this study was a “universal” intervention, as all kids in the included schools and classes participated received the intervention compared to “targetet” interventions, where only those kids who have an elevated risk of developing a condition receive an intervention.
The study highlighted the threats of attrition on the validity of the result (which is a common problem in prevention research). The null result finding is important, as prevention programmes are quite popular in some regions, and valuable time and resources are used in schools, from teachers and pupils when implemented. If there indeed is no tracable effect of anxiety and depression prevention efforts, (as our study indicates), resources should instead be used for other kinds of support that could more effectively promote mental health in schools.
Read the full article here.
We have published a meta-analysis earlier, that is largely in line with the current study, not showing long-term effects for anxiety, but a small, significant long-term effect for depressive symptoms (find it here).
Ahlen, J., Lenhard, F., & Ghaderi, A. (2019). Long-Term Outcome of a Cluster-Randomized Universal Prevention Trial Targeting Anxiety and Depression in School Children. Behavior Therapy, 50(1), 200–213. https://doi.org/10.1016/j.beth.2018.05.003