The effect of trauma and dissociation on the outcome of cognitive behavioural therapy for binge eating disorder: A 6-month prospective study

Background: Binge eating disorder (BED) is commonly associated with a history of trauma. Yet, there is little insight into the potential effect that trauma, dissociation, and depressive symptoms may have on the outcome of treatment interventions. Methods: A total of 142 treatment-seeking patients admitted with a diagnosis of DSM-5 BED (88% female; mean age = 38.7; SD = 10.8) took part in a 6-month, protocolized, group cognitive behavioural therapy (CBT). Self-report questionnaires were administered to assess lifetime traumatic experiences, dissociation, and depression. Body mass index and the number of binges per week (BPW) were measured throughout treatment. The main outcomes were the percentage reduction in BPW and remission (i.e., less than one BPW; cf. DSM-5). Results: Most BED patients (91.5%) reported a history of trauma, with two in three patients reporting three or more traumatic experiences. Whereas the number of traumatic experiences was not significantly associated with a reduction in BPW or remission, a higher traumatic impact score significantly decreased the likelihood of obtaining remission at the end of treatment (OR = 0.96; 95% CI [0.92, 0.99]). Higher levels of dissociative symptoms partially mediated this prospective association. Conclusions: The impact of traumatic experiences, as opposed to the number of traumatic experiences experienced, negatively predicts remission after 6 months of CBT. These findings highlight the importance of addressing trauma and dissociative features in the CBT treatment of BED.