Temporal sequencing of symptom change in youth receiving treatment for posttraumatic stress disorder and substance use: secondary findings from a randomised controlled trial

07/03/2026

Eur J Psychotraumatol. 2026 Dec;17(1):2630609. doi: 10.1080/20008066.2026.2630609. Epub 2026 Mar 6.

ABSTRACT

BACKGROUND: Posttraumatic stress disorder (PTSD) and substance use disorders (SUD) frequently co-occur in youth. Integrated, trauma-focused treatments are recommended, but evidence in youth is limited and the dynamics of symptom change are poorly understood.

OBJECTIVES: We investigated within-treatment changes in PTSD and substance use, and their temporal sequencing, in a randomised controlled trial (RCT) comparing integrated treatment with supportive counselling among youth aged 13-25 years.

METHOD: Participants (n = 55) were randomised to an integrated, exposure-based treatment, Concurrent Treatment of PTSD and SUD Using Prolonged Exposure – Adolescent version (COPE-A); or supportive counselling, Person-Centred Therapy (PCT). PTSD and substance use symptoms were assessed at each session. Generalised estimating equations were used to analyse symptom change over time, and Spearman’s correlations were used to examine associations between early (sessions 1-5) and later (sessions 5-11) change.

RESULTS: COPE-A showed significantly greater reductions in total PTSD symptom severity during treatment (β = -17.00, 95% CI -29.50 to -4.46); with no between-group differences in substance use quantity or frequency. PTSD symptom clusters improved concurrently, but no temporal relationships were observed. Temporal relationships for substance use change were limited, and changes in PTSD symptoms were not associated with concurrent or subsequent changes in substance use.

CONCLUSION: Integrated, trauma-focused treatment reduced PTSD symptoms, reinforcing the safety and tolerability of exposure-based therapy in this youth sample with comorbid PTSD-SUD. PTSD improvement was not associated with either concurrent or subsequent reductions in substance use. Understanding temporal patterns of change may help refine models of PTSD-SUD comorbidity and optimise intervention delivery.

PMID:41791032 | DOI:10.1080/20008066.2026.2630609

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