The impact of dissociation on PTSD treatment with cognitive processing therapy

This secondary analysis of data from a randomized controlled trial of cognitive processing therapy (CPT) and its constituent components investigated whether dissociation decreased over the course of treatment primarily targeting symptoms of posttraumatic stress disorder (PTSD) and explored whether levels of dissociation predicted treatment outcome differentially by treatment condition.

An intention to treat sample of 150 women were randomized to CPT, cognitive therapy only (CPT-C) or written trauma accounts only (WA). Dissociation was measured by the dissociation subscale of the Traumatic Stress Inventory and the Multiscale Dissociation Inventory.

Multilevel regression analyses revealed significant decreases in dissociation that did not vary as a function of treatment condition. Growth curve modeling revealed significant treatment condition by dissociation interactions such that the impact of pretreatment levels of dissociation impacted the treatment conditions differently.

Women who endorsed low pretreatment levels of dissociation responded most efficiently to CPT-C, whereas women with the highest levels of dissociation, in particular high levels of depersonalization, responded better to CPT.