This study evaluated mechanisms, mediation, and secondary/exploratory outcomes in our randomized controlled trial evaluating dialectical behavior therapy (DBT) compared to individual and group supportive therapy (IGST). We expand on previously reported results indicating a DBT advantage at posttreatment on planned suicide/self-harm outcomes, and greater self-harm remission (absence of self-harm, post hoc exploratory outcome) during active-treatment and follow-up periods.

This was a multi-site randomized trial of 173 adolescents with prior suicide attempts, self-harm, and suicidal ideation. Randomization was to 6 months of DBT or IGST, with outcomes monitored through 12 months. Youth emotion regulation was the primary mechanistic outcome.

Compared to IGST, greater improvements in youth emotion regulation were found in DBT through the treatment-period [t(498) = 2.36, p = .019] and 12-month study period (t(498) = 2.93, p = .004). Their parents reported using more DBT skills: posttreatment t(497) = 4.12, p < .001); 12-month follow-up t(497) = 3.71, p < .001). Mediation analyses predicted to self-harm remission during the 6- to 12-month follow-up, the prespecified outcome and only suicidality/self-harm variable with a significant DBT effect at follow-up (DBT 49.3%; IGST 29.7%, p = .013). Improvements in youth emotion regulation during treatment mediated the association between DBT and self-harm remission during follow-up (months 6−12, estimate 1.71, CI 1.01−2.87, p = .045). Youths in DBT reported lower substance misuse, externalizing behavior, and total problems at posttreatment/6 months, and externalizing behavior throughout follow-up/12 months.

Results support the significance of emotion regulation as a treatment target for reducing self-harm, and indicate a DBT advantage on substance misuse, externalizing behavior, and self-harm-remission, with 49.3% of youths in DBT achieving self-harm remission during follow-up.

Collaborative Adolescent Research on Emotions and Suicide; https://www.clinicaltrials.gov/; NCT01528020