Eating Disorders and Depression

Coexisting mood disorders have been reported in more than 40 percent of people with eating disorders. This explains why a large subgroup of patients with eating disorders are diagnosed with clinical depression, also known as major depression or major depressive disorder, and are treated with antidepressant medications. However, a diagnosis of coexisting clinical depression is often inappropriate because there is a substantial conceptual overlap between some features of the two disorders. Therefore, it is not easy to discern whether the coexistence of an eating disorder and depression constitutes true or spurious comorbidity. Still, an attempt must be made to prevent the superfluous prescription of antidepressants to patients seeking eating-disorder treatment.

How to tell if depression is secondary or real

It is well known that in anorexia nervosa, many features used for the diagnosis of clinical depression are the consequences of being underweight. Examples are as follows:

• Low mood
• Social withdrawal
• Heightened obsessionality and indecision
• Disturbed sleep with early waking
• Decreased energy and drive
• Loss of sexual desire
• Impaired concentration
• Irritability

Similarly, in bulimia nervosa, many features used for the diagnosis of clinical depression are known to be the consequence of recurrent binge-eating episodes. Examples are as follows:

• Self-criticism
• Low mood
• Social withdrawal
• Shame
• Guilt
• Feelings of impotence

On the other side of the coin, features suggestive that there is, in fact, clinical depression coexisting with the eating disorder are the following:

• A personal history of clinical depression before the onset of the eating disorder
• Late eating disorder onset
• Recent intensification of depressive features in the absence of any change in the eating-disorder psychopathology (e.g., low mood, social withdrawal, or suicidal thoughts and plans)
• Loss of interest, crying, recurrent thoughts on the pointlessness of life, personal neglect

The more of these features reported by the patient, the more confident we are that a diagnosis of clinical depression is warranted.

Why it's important to distinguish secondary depression from real depression

The distinction between depression secondary to the eating disorder and coexisting clinical depression is essential for an optimal therapeutic intervention. In the former case, the depressive features should not be treated because they tend to resolve alongside an improvement in the eating-disorder psychopathology. Indeed, addressing the consequences of an eating disorder with a pharmacological or psychological treatment designed for another psychiatric disorder may increase the risk of deviating from the treatment of the eating-disorder psychopathology. Furthermore, they expose the patients to side effects without the possibility of achieving significant improvements.

In contrast, coexisting clinical depression must be identified and treated because it hinders the treatment of the eating disorder itself. Those suffering from coexisting clinical depression may think that it is impossible to change, have little energy to engage in the treatment, and have a level of concentration too low to understand and retain the information provided.

When and why to use antidepressants

The indication to use antidepressants for at least 9-12 months rather than a psychological treatment to address the coexisting clinical depression with eating disorders is based on two principal observations: (i) psychological treatment of clinical depression requires a lot of time, and progress is limited by the presence of the eating disorder as the two psychopathologies negatively interact; and (ii) antidepressants, in particular SSRIs (e.g., fluoxetine and sertraline), generally work rapidly and well in people with eating disorders.

If a patient has reservations about taking antidepressants, they should be informed that these psychopharmacological agents do not interfere with the ability to do things in life and that the resolution of clinical depression will allow them to be in the best condition to handle the psychological treatment of their eating disorder. In addition, antidepressant drugs are not addictive, are not mood enhancers (they only treat depression), and have few side effects (e.g., nausea), which are usually transient and last only a few days. The patient should be reassured that should they develop more persistent side effects, such as a fine hand tremor, difficulty swallowing, and decrease or loss of sexual desire, their antidepressant regime will be reassessed.

Eating disorder patients will also be interested to know that SSRIs do not increase appetite, although fluoxetine at higher doses can reduce the propensity to binge-eat. They should be warned that SSRIs are, however, associated with a greater sensitivity to the intoxicating effects of alcohol, and so be advised to drink with caution.