Cognitive-behavioural therapy (CBT) is the most effective psychological treatment for a variety of eating disorder presentations in adults. However, little is known about how, why, or through what mechanisms, CBT achieves its effects. The cognitive theory that underpins cognitive-behavioural treatment proposes that CBT “works” through modifying dietary restraint and dysfunctional attitudes towards body weight and shape, as these are the two central mechanisms assumed to maintain eating disorder psychopathology. However, little direct empirical evidence exists supporting this cognitive model of change. As an important first step toward validating this cognitive model, this meta-analysis aimed to examine whether CBT is indeed effective in modifying these maintaining mechanisms, by comparing CBT to (1) control conditions and (2) non-CBT psychological interventions in individuals with eating disorders.
Twenty-nine randomized controlled trials were meta-analyzed. The meta-analysis showed that CBT for bulimic-type disorders was significantly more effective than control conditions in reducing dietary restraint and shape and weight concerns, with moderate effect sizes. CBT was also significantly more effective than non-CBT interventions in reducing these maintaining mechanisms. Importantly, it was found that the magnitude of improvements in binge/purge symptoms was predicted by the magnitude of improvements in these maintaining mechanisms, suggesting that greater changes in these mechanisms were associated with greater symptom improvement. Overall, these findings demonstrate that CBT is also the most effect treatment for reducing the core eating disorder maintaining mechanisms. This study highlights the need for further research to explore whether changes in these mechanisms during CBT are causally linked to symptom reduction.
Read the full paper: Linardon, J. (in press). Meta-analysis of the effects of cognitive-behavioral therapy on the core eating disorder maintaining mechanisms: implications for mechanisms of therapeutic change. Cognitive Behaviour Therapy. doi:10.1080/16506073.2018.1427785
Photo by: Richard McKenzie