3 - (SYM 5) The Efficacy and Mechanisms of Dialectical Behavior Therapy for Suicidal Ideation, Depression, and Anxiety in Female Offenders: A Randomized Controlled Trial

Introduction: Suicide poses a critical threat in correctional facilities, with female offenders exhibiting disproportionately high rates of suicidal ideation and mood disorders. Dialectical Behavior Therapy (DBT) targets emotion dysregulation, yet its mechanisms in forensic populations remain unclear. This randomized controlled trial (RCT) evaluated the efficacy of DBT and examined whether symptom improvements were mediated by mindfulness, experiential avoidance, and thwarted belongingness.


Methods: Seventy-three female offenders were randomized to DBT (n=34) or treatment-as-usual (TAU) (n=39). Assessments occurred at baseline (T0), post-treatment (T1), and1- and 3-month follow-ups (T2,T3). Primary efficacy was analyzed using Linear Mixed Models. Longitudinal mediation (5,000 bootstraps) tested whether mechanism changes at T1 mediated outcomes at T2, controlling for baseline.


Results:  Compared to TAU, DBT yielded significantly greater reductions in depression (β = −0.64, p< .001), anxiety (β = −0.55, p= .001), and suicidal ideation (β = −0.56, p= .002). Improvements in suicidal ideation were sustained and enhanced during the follow-up (Group × Time β = −0.13, p= .016). DBT  significantly improved all mechanism variables (p≤.001). Longitudinal mediation revealed that reduced thwarted belongingness (T1) mediated improvements in all T2 outcomes. Crucially, distinct pathways emerged for mood: T2 depression reduction was uniquely mediated by increased T1 mindfulness (indirect effect = −0.143, 95% CI [−0.325,−0.021]), whereas T2 anxiety reduction was driven primarily by reduced T1 experiential avoidance (indirect effect = −0.202, 95% CI  [−0.424,−0.012] ).


Conclusion: DBT demonstrated sustained efficacy for suicidal ideation, depression, and anxiety in female offenders. Findings underscore mechanism specificity: while thwarted belongingness served as a universal mediator, mindfulness uniquely drove depression improvement, and experiential avoidance drove anxiety reduction. These results support transdiagnostic yet distinct mechanistic pathways in forensic DBT, highlighting the importance of targeting social connection and emotion regulation.