Eating Disorders and Substance Use Disorders
vol. 12-1
By Kenneth Bruce, Ph.D
Psychologist, Eating Disorders Program, Douglas Hospital

There are two main types of recognized eating disorders (ED). The most familiar is anorexia nervosa (AN), which is characterized by drastic weight loss, the refusal to maintain a normal weight, and the intense fear of weight gain. Bulimia nervosa (BN) is another common ED. It is typified by frequent - at least twice a week - binge-eating episodes and compensatory behaviours, such as vomiting, in individuals of relatively normal weight. ED’s mostly affect adolescents and young adults, and are at least ten times more common in females; AN and BN respectively affect nearly 1% and 2% of females between the ages of 13 and 40. ED’s frequently co-aggregate with other psychiatric disturbances; namely depression (e.g., major depressive disorder, seasonal affective disorder), anxiety (e.g., social anxiety disorder, obsessive-compulsive disorder), and personality disturbances (e.g., clinical perfectionism). ED’s that involve binge eating or purging are also associated with a propensity for impulsive or self-harming behaviours as well as alcohol and drug addictions, also known as substance use disorders (SUD).

There are two main types of SUD’s. The most severe form is dependence, which is characterized by intense cravings and loss of control over alcohol or drug use. It often entails an acquired tolerance to their effects or severe withdrawal symptoms. The second form is abuse, characterized by the destructive use of alcohol or drug, which can lead to personal or legal problems and may involve episodes of binge-drinking or excessive drug use. Abuse and dependence are the most common SUD’s for men and women. They affect close to 5% of women. The dependence and abuse of illicit (stimulants, hallucinogens) and prescription (sedatives, tranquilizers, opioids) drugs vary between 1 and 2% for each substance. In treatment settings, alcohol-related SUD’s and ED’s that involve binge-eating or purging often overlap: up to 30% of women will develop both conditions in their lifetime. This coexistence is often a source of major concern; when both conditions are present at the start of the treatment, the success rate of the treatment - for either condition - is lessened considerably.

The Relation between ED’s and SUD’s

In treatment settings, it is relatively common for patients to think that SUD’s and ED’s that involve binge eating or purging are connected. This reasoning comes from four key principles:

• Both SUD’s and ED’s involving binge-eating or purging are characterized by impulsive or risky behaviours.
• Because the concurrence of these two conditions is common, patients are often in contact with individuals who suffer from both conditions.
• Many ED patients report alcoholism or drug addiction in their family circle.
• Purging behaviours, as seen in some ED cases, can include the misuse of laxatives, diuretics, hallucinogens, and stimulants.

While the correlation may simply be intuitive to patients, and it may indeed be tempting to speculate about some overlapping risk or causal factors to these conditions, studies suggest that this may not reflect reality. The evidence that ED’s and SUD’s are distinct conditions is in fact quite compelling.

ED’s and SUD’s are characterised by impulsive or risky behaviours. Though this may be common ground to both conditions, such behaviours can vary extensively: self-induced vomiting, binge drinking, self-harming, and shoplifting are indeed very dissimilar in nature. What’s more, some people may engage in only one of these behaviours while others, in several of them. Research also shows that the underlying psychological risk factors for each of these impulsive or risky behaviours are unconnected. Although the overlapping of SUD’s and ED’s is common among patients in treatment settings, the coexistence of both conditions is not as frequent within the community. We need to remember that patients seeking treatment for an SUD or ED are not a representative sample of the population at large. Uncovering the causes of ED’s and SUD’s requires extending research to include individuals beyond clinical patients.

Though many individuals with an ED report the presence of an SUD in a family member, research shows that ED’s and SUD’s are genetically unrelated conditions. Indeed, while they tend to run in the family, evidence shows that each condition ‘runs’ separately from the other. For example, family members of ED patients with binge-eating or purging (who have never had an SUD) do not have a higher risk of developing an SUD. This suggests that the genetic roots of ED’s and SUD’s are different, and that ED’s and SUD’s are not merely different versions of the same underlying pathology (such as impaired emotion regulation or generalized impulsiveness).

While ED purging behaviours may include the use of stimulants, laxatives, or diuretics, the criteria required to diagnose abuse or dependence are usually not met. This implies that although many ED patients use or misuse substances, they do not always develop an abuse or dependence disorder. For a therapy to be successful, it is thus crucial to understand the motivation for using or misusing substances. ED patients will often misuse substances to “service” their ED, i.e., to lose or control their body weight. By contrast, SUD patients are often more motivated by the immediate physical, psychological, or social effect of consuming substances, e.g., to relieve withdrawal or boredom, to induce euphoria, or to self-medicate anxiety or depression. ED patients with binge-eating or purging behaviours often aberrantly expect “positive” effects from thinness, dieting, and purging: food restriction may make them feel more relaxed, more confident, more capable, etc. While SUD patients have similar beliefs regarding drugs and alcohol (drinking or using may make they make them feel more excited, more sociable, etc.), they do not have aberrant beliefs about thinness, dieting, or purging. The same applies to ED patients (who don’t have an SUD): they do not have deviant beliefs about alcohol or drugs. Such findings suggest that the underlying impetus of ED’s and SUD’s are distinct, and that the mental and emotional risk factors behind these two conditions are unrelated.

Implications

ED’s and SUD’s have distinct causes and risk factors. In other words, an ED would not be justly characterised as an addiction, and vice versa. Individuals seeking treatment for one of these conditions would consequently be best served by specialized ED or SUD therapies. There is still no proven program that can treat both conditions with the same approach or philosophy. Because risk factors and causes differ, following separate, specialized treatments appears to be the best option for individuals struggling with both conditions. As for whether treatments should be sought concomitantly or in sequence depends on individual needs. It is best to discuss it with the people responsible for the ED and SUD treatment programs.

Summary

AN and BN are the two most familiar ED’s while dependence and abuse are the two most common SUD’s. An ED involving binge eating or purging behaviours may coexist with an SUD. Such co-occurrence is common: approximately 30% in treatment settings. Though this correlation can make it seem like ED’s and SUD’s are related conditions, research shows that they have distinct risk factors and underlying causes. Individuals who suffer from both conditions need to seek treatment that will address each separately, whether this is done in the same or distinct settings.

Kenneth Bruce, PhD
Eating Disorders Program
Douglas Hospital & Department of Psychiatry
McGill University
Tel.: 514.761.6131, ext 2895
Fax: 514.888.4085