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Comorbidity of mental disorders and substance use: a brief guide for the primary care clinician

9.2 Comorbidity with eating disorders

Table of contents

9.2.1 Comorbidity with substance use

People with bulimia or bingeing/purging behaviours are more likely to use substances or have a substance use disorder than people with anorexia (in particular the restricting type) or the general population^(346-351).
Results from studies of bulimia and anorexia populations suggest that those people who use pharmacological methods of weight control (including laxatives, diet pills and diuretics) are more likely to use more traditional substances such as stimulants⁽³⁵²⁾.
A variant of eating disorders has been described where people have difficulty with 'multi-impulse control'⁽³⁵³⁾. These people are more prone to problems in a variety of areas of impulse control in the setting of their bulimic illness, including substance use. People with comorbid bulimia and substance use problems are more likely to attempt suicide, be impulsive and have personality disorders^{(350, 351, 354-356)}.
The risk of substance use disorder in people with eating disorders continues over time and should be an ongoing part of assessment of these people^{(347, 354, 357, 358)}. However, age-related tapering of substance use may decrease the incidence^{(347, 359)} as does retention in treatment ⁽³⁴⁷⁾.
Drug use may assist with weight control and may be a part of impulsiveness and loss of control⁽³⁶⁰⁾. It may also be a part of a risk taking or self harming pattern of behaviour⁽³⁶¹⁾.

People with eating disorders across all types have higher rates of mental disorders in general (reported up to 97% comorbidity)^{(346, 347)}, in particular, mood and anxiety disorders^{(346, 347, 354, 362)}. These other mental disorders increase the severity and chronicity of the eating disorder as well as impact on the willingness to accept treatment^{(346, 363)}.
People with bulimia or bingeing behaviours have high rates of other impulse control disorders (e.g. compulsive buying and pathological gambling) and, combined with personality disorders, show high rates of novelty seeking behaviour^(364-367).
In addition, consistent personality differences exist between people with anorexia and bulimia^{(351, 356)}. It has been suggested that the less inhibited and more impulsive personality style associated with bulimia may predipose people to substance use^{(341, 346, 351, 363)}.
People with anorexia (particularly the restricting type) have higher rates of obsessive compulsive disorders^{(346, 368)}.

Practitioners should always anticipate mental disorders and substance use comorbidity in people with eating disorders^{(346, 347)}, particularly those with binge/purging types.
Treatment and prevention should be directed towards assisting individuals at risk in understanding the nature of their emotions and subsequently developing positive coping strategies to handle them⁽³⁵⁰⁾.
The disruptive symptoms of eating disorders can interfere with therapy for substance use disorders**⁽³⁵⁷⁾ and vice versa.
When assessing people with eating disorders, a detailed drug history should be elicited and should include specific inquiry about alcohol and stimulants as well as diuretics, laxatives and thyroxine.