Changes during treatment for bulimia nervosa: a comparison of three psychological treatments.

Seventy-five patients with bulimia nervosa were treated with cognitive behaviour therapy, behaviour therapy or interpersonal psychotherapy. The changes that occurred during treatment were assessed in a subsample of 38 patients. There was an immediate decrease in the frequency of binge-eating and purging (self-induced vomiting or laxative misuse). This continued for 4 wk in interpersonal psychotherapy and for 8 wk in the other two treatment conditions. There were no clear differences between the three treatments in the time course of their effects on a global measure of eating behaviour and attitudes or on measures of depression and self-esteem. The findings suggest that certain shared 'non-specific' properties of psychological treatments can have a substantial early effect on the eating behaviour of patients with bulimia nervosa. Indeed, patients with bulimia nervosa may be particularly likely to show non-specific treatment effects. Cognitive behaviour therapy and behaviour therapy appear to have an immediate influence on eating behaviour over and above these non-specific effects. The study gave no clues as to the mechanism of action of interpersonal psychotherapy.