Bridging the treatment gap for adolescents with depression : evaluating internet-based guided and self-guided behavioural activation

Background: Depression is a common and leading cause of disability among adolescents worldwide. Depression affects not only individuals but also society and economic productivity. Effective treatments for depression exist, and psychological treatments are the primary option; however, only a minority have access to them. Delivering treatments remotely is one way to narrow the treatment gap. Internet-delivered cognitive behavioural therapy (ICBT) has proven to be an effective method for adults with depression. Yet, properly conducted clinical trials for adolescents with clinical depression are lacking. Digital interventions can be delivered with or without therapist support. If treatment can be delivered in a self-guided manner while ensuring efficacy and safety, it may be more cost-effective and could benefit an even larger number of adolescents.

Aim: The overarching aim of this thesis was to develop and evaluate a scalable treatment for adolescents with mild to moderate depression and assess the importance of therapist support for treatment outcomes. The specific aims per study were: (1) To assess the feasibility and acceptability of both therapistguided and self-guided internet-delivered behavioural activation (I-BA) with parental involvement; (2) To explore adolescents’ and parents’ experiences of therapist-guided and self-guided I-BA treatment; (3) In a study protocol describe the rationale and methods for the RCT; (4) Investigate the clinical efficacy and cost-effectiveness of therapist-guided and self-guided I-BA compared to treatment as usual (TAU).

Methods: This doctoral project included four papers (I-IV). Paper I was a randomised controlled feasibility trial (N=32) to assess the study design's feasibility and the acceptability of the new treatments (I-BA). Paper II was a qualitative study in which eight adolescents and nine parents participated, sharing their experiences of I-BA. Thematic analysis was employed to analyse the data. Paper III details a protocol for the RCT (Study IV) with a planned sample of 215 participants aged 13-17 with mild to moderate depression, comparing therapist-guided I-BA versus TAU and self-guided I-BA versus TAU. Paper IV was a single-blinded, randomised controlled trial involving 219 adolescents aged 13 to 17 years with mild to moderate depression who were randomised to receive either therapist-guided I-BA, self-guided I-BA, or TAU. Clinical efficacy and cost-effectiveness were analysed at 3-months follow-up (the primary endpoint).

Results: In Study I, we had two dropouts (in TAU), no severe adverse events, and high treatment completion rates in therapist-guided I-BA, and acceptable rates in self-guided I-BA. The results indicated large and statistically significant reductions in depressive symptoms assessed by clinicians in both I-BA groups, whereas changes in TAU were not significant. In Study II, although some participants found it difficult to engage with and benefit from online BA, the overall results indicated that internet-based BA for adolescents with depression is beneficial and generally well-received, particularly when supported by a therapist and parents. Study IV demonstrated that therapistguided I-BA was both more effective and more cost-effective compared to TAU at three months after ending treatment. Self-guided I-BA was not superior to TAU in clinical efficacy; however, treatment costs were statistically lower. Two serious adverse events for the same participants were reported in this trial, none assessed related to the trial participation.

Conclusions: A therapist-guided, internet-based BA intervention is an acceptable, safe, effective, and cost-effective treatment for adolescents with depression when compared to TAU. Although self-guided I-BA was not statistically superior to TAU regarding efficacy, it could still serve as a feasible option for treatment and healthcare system costs if therapist support is unavailable. Pragmatic trials to evaluate this intervention in routine care and replication by independent researchers are encouraged to verify these findings. Continued development of I-BA treatments to enhance both engagement and the proportion of treatment responders is necessary.

List of scientific papers

I. Andersson, R., Ahlen, J., Mataix-Cols, D., Lenhard, F., Henje, E., Månsson, C., Sahlin, H., Beckman, M., Serlachius, E., & Vigerland, S. (2022). Therapistguided and self-guided internet-delivered behavioural activation for adolescents with depression: a randomised feasibility trial. BMJ Open, 12(12), e066357–e066357.
https://doi.org/10.1136/bmjopen-2022-066357

II. Andersson, R., Vigerland, S., Ahlen, J., Widström, H., Unger, I., Serlachius, E.,

& Engberg, H. (2024). “Therapy without a therapist?” The experiences of adolescents and their parents of online behavioural activation for depression with and without therapist support. European Child & Adolescent Psychiatry, 33(1), 105–114.
https://doi.org/10.1007/s00787-023-02142-7

III. Andersson, R., Vigerland, S., Lenhard, F., Ahlen, J., Bottai, M., Mataix-Cols, D., & Serlachius, E. (2024). Single-blinded, randomised, parallel-group, controlled trial comparing the efficacy and cost-effectiveness of

therapist- and self-guided internet-delivered behavioural activation versus treatment as usual for adolescents with mild to moderate depression: study protocol. BMJ Open, 14(10), e083507-.
https://doi.org/10.1136/bmjopen-2023-083507

IV. Andersson R., Ahlen., J., Lenhard, F., Ohlis, A., Wachtmeister, V., Karemyr,

M., Hogström, J., Bottai, M., Mataix-Cols, D., Vigerland, S., & Serlachius, E. (2025). Therapist- and self-guided internet-based behavioural activation versus treatment as usual for adolescents with mild to moderate depression: a single-blinded, randomised controlled trial with embedded economic evaluation. [Submitted]