Major Depressive Disorder and Eating Disorders: Watch for a Comorbid Connection

Eating disorders and affective disorders are no strangersmajor depressive disorder (MDD) and dysthymia are among the most commonly reported comorbid Axis I disorders in individuals with bulimia nervosa (BN) and anorexia nervosa (AN). However, despite many studies, the relationship and mechanisms between MDD and eating disorders is still only partially understood.

A large collaborative study has shown that eating disorders and MDD first occur relatively closely together, within a 3-year window. Dr. Fernando Fernandez-Aranda and colleagues found that 43.6% of onsets of MDD and an eating disorder occurred within 1 year of each other and 67% within 3 years (Austral N Zealand J Psychiatry 2007; 41:24). The lifetime prevalence of MDD by eating disorder subtype is shown in the table.

The study

Lifetime MDD and depressive symptoms were evaluated in 1371 women with a history of eating disorders (AN, restricting and purging subtypes, BN, purging and nonpurging subtypes, and eating disorders not otherwise specified, or EDNOS). The researchers first explored the prevalence of MDD across eating disorder subtypes and ages of onset of MDD and the eating disorders were compared.

Symptoms of depression were examined in women who developed MDD before and after the onset of the eating disorder. The researchers were particularly interested in whether the nature of the MDD differed in those individuals who developed depression prior to an eating disorder.

Results

Dr. Fernandez-Aranda and his colleagues found that patients who developed MDD before an eating disorder had a longer duration of symptoms of MDD, more frequent psychomotor agitation, and greater thoughts of their own death than did those who developed an eating disorder first. However, the authors did not find a greater degree of suicidality among those individuals who developed eating disorders after MDD.

The authors also reported that several factors might explain the proximity of the two types of disorders.

First, stressful triggering events, such as puberty, trauma, or transitional times in life, may activate processes that lead to the expression of both MDD and eating disorders in individuals who are genetically vulnerable to both disorders.

Second, in instances where MDD emerges first, factors associated with MDD, including loss of appetite or low self-esteem, may themselves activate underlying genetically mediated vulnerability to eating disorders.

Finally, among those who develop an eating disorder, the first, aspects of the disorder, such as starvation, may serve as triggers for an underlying latent vulnerability to MDD.

Dr. Fernandez-Aranda and colleagues noted that the clinical implications of their study are clear. The period of time bracketing the onset of an eating or affective disorder is a high-risk time for developing additional psychopathology in at-risk individuals.

Increased vigilance urged

The researchers note that clinicians treating individuals with new-onset eating disorders or MDD should remain vigilant for the emergence of additional psychopathology, especially during the first 3 years after the onset of the first disorder. This is particularly true for individuals who have a family history of eating disorders or major depression.