Estimated Intelligence Moderates Cognitive Processing Therapy Outcome for Posttraumatic Stress Symptoms

Abstract

Although patient intelligence may be an important determinant of the degree to which individuals may comprehend, comply with, and ultimately benefit from trauma-focused treatment, no prior studies have examined the impact of patient intelligence on benefit from psychotherapies for PTSD. We investigated the degree to which educational achievement, often used as a proxy for intelligence, and estimated full scale intelligence quotient (FSIQ) scores themselves moderated treatment outcomes for two effective psychotherapies for PTSD: Cognitive Processing Therapy (CPT) and Written Exposure Therapy (WET). Participants, 126 treatment-seeking adults with PTSD (52% male; mean age = 43.9, SD = 14.6), were equally randomized to CPT and WET; PTSD symptom severity was measured at baseline and 6-, 12-, 24-, 36-, and 60-weeks following the first treatment session. Multilevel models revealed that participants with higher FSIQ scores experienced significantly greater PTSD symptom reduction through the 24-week assessment in CPT but not WET; this effect did not persist through the 60-week assessment. Educational achievement did not moderate symptom change through either 24- or 60-weeks. Individuals with higher FSIQ who are treated with CPT may experience greater symptom improvement in the early stages of recovery.

Keywords: PTSD; cognitive-behavioral treatment; moderators; trauma.

FIGURE 1

Moderation of slope of change in PTSD symptoms by estimated full-scale IQ in Cognitive Processing Therapy and Written Exposure Therapy. Please note that multilevel modeling was used to examine the effect of estimated IQ on PTSD outcome.