Posttraumatic stress disorder as a moderator of the association between negative affect and bulimic symptoms: an ecological momentary assessment study.

OBJECTIVE: The purpose of this study was to examine the potential moderating effect of posttraumatic stress disorder (PTSD) on the emotion-behavior relationship in individuals with bulimia nervosa (BN).
METHOD: A total of 119 women with BN were involved in the study. Participants were divided into 2 groups: those with BN and PTSD (n = 20) and those with BN only (n = 99). Ecological momentary assessment procedures were used for the examination of affect, frequency of bulimic behaviors, and the relationship of affect and bulimic behavior over time. The Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Axis I Disorders was conducted for the diagnosis of BN, PTSD, mood disorders, anxiety disorders, and substance use disorders. Mood disorders, anxiety disorders, and substance use disorders functioned as covariates in all analyses.
RESULTS: Statistical models showed that those in the PTSD group reported a greater daily mean level of negative affect (NA) and a greater daily frequency of bulimic behaviors than those in the BN-only group. Moderation was found for the association between NA and time in that the PTSD group showed a faster acceleration in NA before purging and faster deceleration in NA after purging. The association between positive affect and time was also moderated by group, indicating that the PTSD group had a faster acceleration in positive affect after purging than the BN-only group.
CONCLUSION: These findings highlight the importance of recognizing PTSD when interpreting the emotion-behavior relationship in individuals with BN. Published by Elsevier Inc.