Major depressive disorder (MDD/depression) is a common and disabling condition that often begins between adolescence and mid-adulthood (Kessler & Bromet, 2013). Around 40% of individuals experience their first episode before age 20, with a median onset of 25 years (Kessler et al., 2005; Malhi & Mann; Schwartz & Timothy, 2009).
Although early-onset depression has been linked to poorer social functioning, reduced quality of life, and higher recurrence (Zisook et al., 2007), direct comparisons with adult-onset depression are limited. Methodological differences in sample selection, outcome definitions, and analyses have made it difficult to determine whether adolescent-onset depression carries higher long-term risk or requires distinct treatment approaches from adult-onset depression.
To address this, Desai Boström and colleagues (2025) conducted a population-based study of healthcare data in Stockholm, Sweden, applying the same analytic strategy across age groups. The study tested whether age at first diagnosis influences the risk or timing of depression recurrence over a five-year period.
Does age at first depression episode influence recovery and recurrence? Desai Boström et al. (2025) compared differences between adolescent- and adult-onset depression.
Methods
Design
This was a retrospective cohort study, using data from the Stockholm MDD cohort. The dataset includes medical records, prescriptions, therapy sessions, and hospital visits for all individuals diagnosed with MDD in Stockholm between 2010 and 2018.
Participants
9,124 individuals (aged 13-40 years) with first MDD diagnosis between 2011–2012 were included. To ensure true first-episodes, anyone with psychiatric diagnoses (e.g., depression, bipolar, psychosis, substance use) in the prior 10 years was excluded. Participants were grouped into adolescents (ages 13–17; n = 1,727) and adults (ages 18–40; n = 7,397).
Main outcomes
- Recurrence: a new MDD diagnosis after a remission period of at least 90 days (90-day period without depression-related treatment or diagnosis)
- Time to recurrence: number of days between remission and recurrence.
Analysis
- A regression model was conducted to examine recurrence over 5 years, adjusting for differences in treatment, illness severity and comorbidities using propensity score (PSW) and inverse probability weighting (IPTW)
- Time to recurrence was assessed using Cox proportional hazards models
- Sensitivity analyses used stricter definitions of remission (180 and 365 days) to test for robust findings
- The authors also:
- Analysed age as both a grouped and continuous variable
- Used bootstrap replications to check model stability
- Applied alternative models (e.g. additive hazards models) where needed
Results
There was no significant difference in recurrence likelihood (mean ratio = 0.96, 95% CI [0.88 to 1.05], p = .364) or timing (hazard ratio = 1.01, 95% CI [0.91 to 1.13], p = .836) between groups.
About half of both adolescents (46.1%) and adults (49.0%) experienced recurrence within five years, with similar time to recurrence (adolescents = 379 days; adults = 326 days).
This indicates both developmental periods shared similar risks and timing for depression recurrence in this study population. Findings were consistent across alternative remission thresholds and modelling strategies, supporting their robustness.
Around 50% of people with a first depression episode—whether adolescent or adult—experienced a recurrence within 5 years.
Conclusions
This large population-based study found that nearly half of individuals who experience a first episode of MDD will have a recurrence within five years, regardless of whether the onset occurs in adolescence or adulthood. Both adolescents and adults had similarly high risks of recurrence and similar time to recurrence.
The absence of significant age differences suggests that depression follows a similar clinical course across these developmental stages, strengthening the case for similar monitoring of MDD following adult and adolescent onset. However, because adolescent symptoms do not fully align with adult depression diagnostic criteria, further research is needed before assuming adult and adolescent depression are the same condition, benefiting from identical treatment approaches.
Adult recurrence rates were somewhat higher than in prior studies, possibly reflecting Stockholm’s accessible healthcare and higher socioeconomic status, which may increase help-seeking and recorded recurrence. Alternatively, this difference may be due to the authors’ rigorous methodology and comprehensive analysis, but further replication is needed.
Recurrence risk was equally high for both adolescent- and adult-onset Major Depressive Disorder, with no significant differences in rate or timing.
Strengths and limitations
Strengths
This study used robust methodology including advanced statistical techniques (e.g., PSW and multiple model types) indicating results are trustworthy and reliable as they were consistent regardless of specific analytical assumptions/methods.
Excluding individuals with prior psychiatric conditions improved internal validity by isolating first-episode, primary MDD cases. This ensured that recurrence rates in the study reflect individuals for whom depression was the main diagnosis, limiting the influence of pre-existing comorbidities, which could inflate rates of recurrence.
By conducting the study within a single regional cohort and health system (Stockholm), authors likely reduced variation in how MDD is diagnosed, which could complicate interpretation (e.g., when comparing across cultures which use different diagnostic systems). This improves the internal validity and trustworthiness of findings.
The study also used a representative sample including population data and propensity weighting to ensure findings accurately represented Stockholm’s population. This makes it likely that findings could apply to other similar multicultural European cities.
Limitations
Despite efforts to minimise confounds, several factors may limit the reliability of the results. First, the absence of mortality data meant that the researchers could not distinguish between participants lost to follow-up due to death versus other causes, which may affect recurrence rate estimates. Additionally, relying on clinical records risks underreporting untreated/undiagnosed episodes, especially in those less likely to seek help, which may differ by age group – for example, adolescents may be encouraged by their teachers and parents to seek mental health support (Hassett, Green & Zundel, 2018).
Authors tried to control for comorbidities and study the impact of depression alone on recurrence rates. However, using ICD-10 codes to identify diagnoses may have missed subclinical or informally diagnosed comorbidities, potentially compromising the purity of the cohort.
Relatedly, excluding people with prior diagnoses may reduce the generalisability of results as many real-world patients have comorbid mental health conditions which often proceed MDD diagnosis.
The scope of this study was also limited as childhood-onset MDD was not included, restricting age-based comparisons across the full developmental spectrum. Moreover, despite the five-year follow-up being longer than many other studies, it may still miss later-life recurrences or the effects of major life transitions (e.g., parenthood, menopause, aging), limiting insight into their impact on recurrence. For instance the perinatal period (from conception to one year post-partum) is associated with increased loneliness and risks for mental health relapse.
Also, whilst this study had a large high-powered sample, effective for detecting moderate differences, smaller effects (e.g., subtle group differences, or differences from changes in remission definitions) could have been overlooked. Further replication is warranted.
Sweden’s health data provided a unique opportunity to compare adolescent- and adult-onset depression using the same methodology.
Implications for practice
This study challenges assumptions that adolescent-onset depression carries a uniquely poor prognosis. Instead, similar recurrence risks across age groups highlight the need for policy makers to support long-term relapse prevention and follow-up for all individuals diagnosed with MDD regardless of age. Services should emphasise routine monitoring, early detection of recurrence, and rapid re-engagement with mental health services. Triage systems that rapidly step up interventions for recurrent episodes (which may be more complicated to treat) may also be beneficial.
The similar recurrence risk and timing across age groups also suggests shared underlying mechanisms (e.g., genetic, neurobiological, environmental), which may encourage adopting adult relapse-prevention strategies for adolescents. However, in the absence of clear guidance for adapting adult treatment approaches adolescents — and given that adolescent symptoms can differ from adults — a person-centred approach that addresses adolescents’ individual triggers and vulnerabilities may be preferable.
Relatedly, future research should investigate predictors of recurrence (such as significant life changes and transitional periods like puberty and menopause), and the impact of symptom severity, duration and comorbidity on relapse to support more effective early-identification and recurrence prevention strategies. To support this, it may be helpful to explore the intensity and impact of recurrent episodes, not just their occurrence and conduct longer-term, multi-recurrence studies across the lifespan.
Research is also needed to assess the generalisability of findings to more diverse cultural, ethnic, and socioeconomic groups than could be included during this study, applying similarly rigorous methods to comparisons of adolescent and adult depression.
Findings suggest long-term follow-up and relapse prevention are crucial for all ages—not just young people. Future research should focus on predictors of recurrence and test whether treatments need to differ by age of onset.
Statement of interests
None.
Links
Primary paper
Desai Boström, A. E., Cars, T., Hellner, C., & Lundberg, J. (2025). Recovery and recurrence from major depression in adolescence and adulthood. Acta Psychiatrica Scandinavica, 151(5), 625-633.
Other references
Hassett, A., Green, C., & Zundel, T. (2018). Parental involvement: a grounded theory of the role of parents in adolescent help seeking for mental health problems. Sage Open, 8(4), 2158244018807786.
Higson-Sweeney, N. (2023). Adolescent depression is not the same as adult depression: new systematic review focuses on adolescents’ lived experiences. The Mental Elf.
Kessler, R. C., Berglund, P., Demler, O., Jin, R., Merikangas, K. R., & Walters, E. E. (2005). Lifetime prevalence and age-of-onset distributions of DSM-IV disorders in the National Comorbidity Survey Replication. Archives of General Psychiatry, 62(6), 593-602.
Keynejad, R. (2024). Community perinatal teams associated with more mental health service access and fewer postnatal relapses. The Mental Elf.
Kingston, F. (2023). “Like being a pretender”: A meta-synthesis of experiences of loneliness in perinatal depression. The Mental Elf.
Malhi, G. S., & Mann, J. J. (2018). Depression. Lancet, 392(10161), 2299-2312.
Zisook, S., Lesser, I., Stewart, J. W., Wisniewski, S. R., Balasubramani, G. K., Fava, M., … & Rush, A. J. (2007). Effect of age at onset on the course of major depressive disorder. American Journal of Psychiatry, 164(10), 1539-1546.
