Mental health outcome of long-term and episodic adolescent depression: 15-year follow-up of a community sample

Background: Recent studies have highlighted the unfavourable natural course of chronic/long-term depression. We investigated the adult mental health outcome of adolescent depression, with specific focus on long-term and episodic adolescent major depression (MD).

Methods: A community sample of depressed adolescents and non-depressed peers was followed-up with a structured diagnostic interview after 15 years. The participants (n=382) were divided into five groups depending on their status in adolescence: no depression (n=155); long-term MD (n=91); episodic MD (n=63); dysthymia (n=33); and subthreshold symptoms (n=40). Outcomes (age 19-31) included mood disorders, other mental disorders, suicidality, and treatment for mental disorders.

Results: The long-term group overall had a poorer outcome than the non-depressed group, with the episodic group in an intermediate position. The outcome of the dysthymic group was similar to that of the long-term group, while the subsyndromal group did not differ markedly from the non-depressed group. The long-term group was more likely than the episodic group to report adult anxiety disorders, multiple mental disorders, suicide attempts, and treatment; they also seemed to develop more persistent adult depressions, with a higher number of recurrent episodes and longer duration of antidepressant treatment. Even after adjustment for adolescent factors of clinical and etiological importance, the long-term group had a markedly less favourable outcome than the episodic group.

Limitation: The participation rate at follow-up was 64.6%.

Conclusion: Longstanding depression in adolescence is a powerful predictor of continued mental health problems in adulthood. It is now important to evaluate if early interventions can alter this severe course.