The diagnostic distinctions above delineate the main forms of eating disorders that exists, and encourages the view of eating disorders as several distinct categories. However, a consideration of the clinical features of eating disorders and the evolution of eating disorder psychopathology challenges this view. Patients with anorexia nervosa, bulimia nervosa and other eating disorders share most clinical features and studies on their course indicate migration between these diagnoses is common and migration to other mental disorders is rare. These two characteristics suggest that there is a case for viewing eating disorders as a single and distinctive diagnostic category rather than as separate disorders.
The implication of the diagnostic classification is that each eating disorder diagnosis requires its own specific form of treatment. This can also be questioned. The fact that eating disorders tend to persist and evolve in their clinical features, but do not tend to migrate into other mental disorders, suggests indeed that common “transdiagnostic” mechanisms play an important role in the maintenance of the eating problem. It seems that there are mechanisms that lock patients into having an eating disorder but not a particular eating disorder. As a consequence treatments designed to address these mechanisms should be effective with all diagnostic categories of eating disorders. The data collected in recent years on the similar effects of CBT-E applied to the various diagnostic categories of eating disorders, both in adolescence and in adulthood, supports this hypothesis.
Figure. The “transdiagnostic” view of eating disorder.
According to this view patients with anorexia nervosa (smaller segment), bulimia nervosa (intermediate segment) and other eating disorders (larger segment) share most clinical features and studies on their course indicate that migration between these diagnoses is common and that migration to other mental disorders is rare. These two characteristics suggest that there is a case for viewing eating disorders as a single and distinctive diagnostic category rather than as separate disorders.
