Background: Major depression is clinically heterogeneous. We aimed to identify classes of depressed adolescents with different symptom presentations and examine if these were differentially associated with illness severity, functioning, engagement with treatment, and clinical outcomes.
Method: Baseline depression symptoms of 454 depressed adolescents (age 11-17) from the IMPACT trial were subjected to latent class analysis. We compared classes on self-reported symptoms and social impairment at baseline and follow-up and their engagement in treatment.
Results: We identified three classes of participants which differed in the number and pattern of depression symptoms; Class 1-Severe- (37.2%)-endorsed almost all symptoms and were most functionally impaired; Class 2-Moderate- (41.9%)-endorsed fewer symptoms with high suicidal ideation, self-harm, and worthlessness; Class 3-Somatic (20.9%)-endorsed fewest symptoms, with high somatic symptoms. Groups did not differ on engagement, therapeutic alliance, or post-treatment symptom reduction. Adolescents in the severe and moderate subgroups reported symptom reductions after treatment ended, whilst those in the somatic subgroup did not.
Conclusions: At presentation, high somatic features in depressed adolescents, rather than severity, or impairment levels, may indicate lower liability for responding to psychological treatment.
Keywords: adolescents; depression; latent class analysis; subtyping; symptoms.