Association between estimated intelligence quotient and treatment outcome in young patients with posttraumatic stress disorder treated with developmentally adapted cognitive processing therapy

Higher pretreatment estimated intelligence quotient (IQ) has been associated with higher treatment gains in adult patients treated with cognitive processing therapy (CPT). We assessed the association between IQ and PTSD treatment outcome in young patients (14–21 years) with childhood abuse-related PTSD treated with developmentally adapted CPT (D-CPT). Participants (N = 44) of a randomized controlled trial assessing the effectiveness of D-CPT were tested with the Culture-Fair Intelligence Test before treatment. PTSD symptomatology was assessed with the Clinician-administered PTSD Scale for Children and Adolescents at baseline, midtreatment, posttreatment, and at 3-, 6-, and 12 months after end of therapy. Multilevel modeling was used to assess the association of IQ and PTSD symptom reduction at all assessment points. Binary regression was used to assess if IQ predicted PTSD remission and dropout. Results showed no association between IQ and PTSD symptom reduction (βIQ x time = .12, t = 1.33, p = .19). IQ did also not predict diagnostic status of PTSD at posttreatment (βIQ = .05, z = 1.22, p = .22) nor dropout (βIQ = –.04, z = –1.04, p = .29). Our results indicate that young patients with PTSD might profit from a D-CPT treatment independent of their IQ.