Haugland, B. S. M., Haaland, Å. T., Baste, V., Bjaastad, J. F., Hoffart, A., Rapee, R. M., … & Wergeland, G. J. (2020). Effectiveness of Brief and Standard School-Based Cognitive-Behavioral Interventions for Adolescents With Anxiety: A Randomized Non-Inferiority Study. Journal of the American Academy of Child & Adolescent Psychiatry.

This Norwegian study found that both brief and standard school-based cognitive behaviour therapy (CBT) were effective in reducing anxiety, impairment and depressive symptoms in adolescents (mean age 14 years), but that brief CBT was not as effective as standard CBT.

https://www.jaacap.org/article/S0890-8567(20)30001-0/fulltext?dgcid=raven_jbs_etoc_email