Treating Dissociation in PTSD: A Meta-Analysis of Psychological Intervention Studies.

Dissociation has increasingly been acknowledged as a key factor in post-traumatic stress disorder (PTSD) and complex PTSD (CPTSD). However, there is evidence that it is not being recognized by clinicians and often trauma treatments do not target dissociation experiences. The purpose of this review was to investigate the effect of any psychological intervention compared to any control on dissociation in adults with PTSD and/or CPTSD. Systematic database searches (PsychINFO, COCHRANE, EMBASE and Medline) were conducted using a predetermined search strategy and inclusion criteria to identify controlled trials reporting psychological therapies for trauma, had a control group and measured dissociation as an outcome. To assess the risk of bias in studies, the Risk of Bias 2 (ROB-2) tool and the Mixed methods appraisal tool (MMAT) were used. Thirteen studies were included in the review. Using a random effect model to perform the meta-analysis, a small effect of current treatments on dissociation experiences was found (g =  -0.28, 95% CI [-0.41, -0.15]; Z =  -4.12, p < .001), with a small level of heterogeneity across studies (I2 = 7.8%). Subgroup analyses showed some important effects across control conditions, therapy modalities and type of measures, albeit overall moderation was not significant in any of the models. While the overall treatment effect was observed when dissociation was a secondary outcome in most studies, for PTSD treatments to be effective on dissociation interventions they need to focus on dissociation more explicitly.