The role of intelligence in PTSD treatment outcomes: evidence from a multicenter TF-CBT trial with youth.

Abstract

Introduction: Cognitive ability has been linked to posttraumatic stress disorder (PTSD) vulnerability and may influence trauma-focused treatment response, yet its role in youth Trauma-Focused Cognitive Behavioral Therapy (TF-CBT) outcomes remains unclear. Clarifying this issue is relevant for equitable access to evidence-based care. We examined whether formally assessed IQ was associated with PTSD symptom change from pre- to post-treatment based on youth and caregiver reports and with treatment dropout in children and adolescents undergoing TF-CBT after abuse or neglect.

Method: Data came from N = 320 youth aged 5-21 years from a randomized clinical effectiveness trial. Intelligence quotient (IQ) was assessed with standardized tests, PTSD symptoms with the Child and Adolescent Trauma Screen (CATS-2), and dropout was defined as not completing therapy as intended. Symptom change was calculated as post- (T1) minus pre-treatment (T0) and evaluated separately for youth and caregiver reports. Regression models included age, gender, baseline PTSD severity, and treatment satisfaction assessed after treatment as an additional model variable.

Results: Mean IQ was M = 97.41 (SD = 13.19, range = 51-138). PTSD severity was high at baseline (M = 34.21, SD = 8.09) and decreased substantially (ΔCATS-2_{T1 ₋ T0} youth report: M = -17.54, SD = 12.34; Cohen's d paired = 1.42). IQ showed small but significant negative correlations with symptom change in youth reports (r = -.14, p = .040) and caregiver reports (r = -.17, p = .018), indicating greater symptom reductions at higher IQ. In regressions, IQ was not a significant predictor in the youth-report model (β = -.10, p = .077), while a small effect remained in the caregiver-report model (β = -.15, p = .011). Baseline PTSD severity and post-treatment satisfaction showed more consistent associations with symptom reduction. Dropout was 29.1%. IQ neither differed between completers and dropouts nor was associated with dropout in logistic regression (OR = 0.99, p = .536), whereas higher post-treatment satisfaction was associated with lower dropout risk.

Discussion: TF-CBT was associated with substantial symptom reductions across the observed IQ range, suggesting its suitability for routine care without excluding youth solely on the basis of cognitive ability. Baseline severity and treatment satisfaction at post-treatment showed stronger associations with symptom change and dropout than IQ. Trial registration The BESTFORCAN study was registered in the German Clinical Trial Registry (DRKS00020516) on 12 February 2020.