For adolescents with subthreshold symptoms, the protocol mattered less than the group

Design

Multicentre, two-arm randomised controlled effectiveness trial with 6- and 12-month follow-up (NCT05322642)

Population

676 adolescents aged 12-18 with subthreshold emotional symptoms; 72.6% female, mean age 13.77; 378 Unified Protocol, 298 active control

Primary outcome

Self-reported depressive and anxiety symptoms at post-intervention, 6 months and 12 months

Effect

Significant reductions in both arms with no significant between-group difference; Unified Protocol favoured for hyperactivity, conduct problems and total difficulties

Subthreshold depression and anxiety in adolescents is where prevention should work, and the question is what to deliver. This multicentre trial randomised 676 adolescents aged 12-18 (72.6% female, mean age 13.8) to the Unified Protocol for Adolescents - a transdiagnostic cognitive-behavioural intervention - or to an active control of protocolised progressive relaxation, delivered in groups in schools.

Both groups improved on self-reported depressive and anxiety symptoms, at post-intervention and at 6 and 12 months, and there were no significant between-group differences on either primary outcome. Adherence was high in both arms, with about 78% attending more than 70% of sessions. The Unified Protocol did better on secondary outcomes - hyperactivity, conduct problems and total mental health difficulties - and marginally on depressive symptoms and neuroticism at 12 months.

The authors read this as a statement about structured group delivery rather than about a specific protocol, and that is the honest reading. What it cannot distinguish is improvement caused by either intervention from the natural course of subthreshold symptoms in adolescence, because there was no no-treatment arm - and subthreshold symptoms frequently remit on their own.

Still, the practical implication is encouraging for systems with no specialist workforce. If a structured, well-delivered group programme in a school produces these results, then the barrier to adolescent mental health provision is organisational rather than technical. In India, where school-based mental health provision is minimal and child psychiatrists are scarce, that matters more than which manual wins.

• For subthreshold adolescent symptoms, structured group delivery in schools is a defensible starting point
• Do not assume a branded transdiagnostic protocol outperforms a well-run alternative on symptoms
• Escalate to individual assessment where symptoms reach diagnostic threshold - that is not what was tested
• The secondary gains were in behaviour and overall difficulties, which are worth measuring separately
• No untreated arm: some of the improvement in both groups is natural remission

The statistics, in plain English

No significant between-group difference in a 676-participant trial is a reasonably informative null: the study was large enough to detect a moderate difference had one existed. But 'both improved' without an untreated arm cannot separate treatment effect from spontaneous remission, which is substantial in adolescent subthreshold symptoms. The secondary outcomes favouring the Unified Protocol were among several tested, so each carries a higher chance of being a false positive than the primary outcomes did.

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