Eating disorders and co-occurring disorders

Commonly co-occurring disorders

Co-occurring, or comorbid, disorders refer to when a person experiences two or more mental health conditions at once. And when it comes to eating disorders, there are some conditions that seem to have a higher rate of comorbidity.

Eating disorders and depression

Eating disorders are deeply connected to mood disorders, including depression. One study of 2,400 individuals found 94% of participants with eating disorders had a co-occurring mood disorder, and 92% of those affected struggled with a depressive disorder.¹

Further research has reported a co-diagnosis of major depressive disorder with:¹

• 32-39% of people with anorexia nervosa (AN)
• 36-50% of people with bulimia nervosa (BN)
• 33% of people with binge eating disorder (BED)

In fact, the two conditions are so closely linked, research has found eating disorders and depression—as well as anxiety—can all be traced back to a shared etiology, or set of common causes.² Other research has suggested that most eating disorders are offshoots of depression itself, representing “variant” forms of depression, rather than their own condition, though these theories are more controversial.³

Whatever the cause, the unfortunate reality is that when these conditions occur together, symptoms are often more severe, prognosis is often poorer, and the burden of illness is often greater.²

Eating disorders and anxiety

Anxiety disorders are the most commonly occurring types of mental health disorders in the United States, but this class of condition is particularly prevalent among people struggling with eating disorders. 

Other studies have shown that having an anxiety disorder increases the likelihood of having or developing an eating disorder—or vice versa—thanks to many related underlying factors in both conditions.⁴

Anxiety disorders and eating disorders both frequently evolve as dysfunctional mechanisms for coping with unpleasant feelings or traumatic events, a powerful shared trait that ties the conditions tightly to one another. This close relationship may also explain, or at least suggest, why symptoms of anxiety sometimes persist even after an eating disorder goes into remission, increasing the risk of relapse.²

{{link-bank-two-column}}

Eating disorders and obsessive-compulsive disorder (OCD)

Research has estimated that anywhere from 11-69% of people with eating disorders also have OCD, while 10-17% of people primarily diagnosed with obsessive-compulsive disorder also struggle with an eating disorder.⁶ And another study found that women who had experienced OCD in childhood had a higher likelihood of developing an eating disorder later on in life.⁵

The biggest overlapping trait between the two conditions may be the way they affect someone’s perspective. Eating disorders often involve a fixation on ideas like body weight, food, and eating, and OCD is also propelled by a narrow field of focus.

“Obsessions,” as they’re understood in obsessive-compulsive disorder, describe frequent and recurrent thoughts or impulses, which eventually become intrusive upon daily life. “Compulsions” are the behaviors or thoughts performed in response to obsessions. 

In cases where someone’s obsession or compulsion involves food, health, or body image, it could manifest as disordered eating behaviors. If this occurs, OCD can act almost as a turbine, powering the behaviors of an eating disorder. The key, in both cases, is that obsessions often lead to rising levels of anxiety that can only be alleviated by performing ritualistic compulsions.⁶

Eating disorders and post-traumatic stress disorder (PTSD)

When someone is struggling with PTSD, they are often affected by unresolved trauma, which can leave them particularly vulnerable or sensitive to any additional stress and all its worst effects, including the development of eating disorders.

Unfortunately, the numbers seem to bear out this observation, with several studies finding lifetime comorbidity rates of PTSD and eating disorders anywhere between 38-44%.⁷

Perhaps the biggest link between these issues is the maladaptive coping mechanisms often involved in both.

When struggling with PTSD, or unresolved trauma that is triggered by an occurrence that’s similar to the original traumatic event, many people revert to something called avoidant coping. This mechanism is characterized by self-punishing and self-defeating thoughts—for example, I’ll never be okay, so nothing good can come from trying. These same types of thoughts are also risk factors for developing eating disorders.⁷

Eating disorders and bipolar disorder

Research examining the comorbid connections between eating disorders and bipolar disorder has been less robust. But at least one study found a co-occurring rate of around 33% between the two conditions.⁸ 

An earlier study on the topic found a higher rate of comorbidity in cases where women had earlier ages of onset and more severe symptoms of bipolar disorder.⁹

Still, some theories on why or how the two conditions impact each other have been developed, mostly through examining qualitative data. In the later study, for example, participants reported struggling with different facets of eating disorders, or different eating disorders altogether, during manic and depressive phases.

Generally, mania was related to overeating, while depression was linked to limiting food intake, leading researchers to theorize that some common factors were directing both these mood swings and the various disordered eating patterns that manifested during their onset.⁸

Eating disorders and substance use disorder

Statistically, substance use disorders and eating disorders co-occur at much higher rates than either condition occurs on its own within the general population.

Up to 50% of people struggling with eating disorders also use alcohol or illicit drugs, a rate that’s five times higher than people without eating disorders. And up to 35% of people with a substance use disorder also have an eating disorder, a rate eleven times higher than the general population.¹⁰

As with many other comorbid relationships, the correlation may hinge on a number of shared traits and risk factors between substance use disorder and many eating disorders, including social pressures, family history, genetics, and brain chemistry.¹⁰

Mood disorders, like anxiety and depression, are also common contributing factors to both substance use disorder and eating disorders, as well as the types of compulsive thinking associated with OCD.¹⁰

Eating disorders and dementia 

Eating behaviors can change during the aging process due to the many physiological, psychological, and social changes a person undergoes at that time. And one of the most common conditions to bring about these changes is dementia.

The age-related disorder presents a number of risk factors for developing a comorbid eating disorder, including appetite changes, sleep disturbance, and depression, among other biochemical changes.¹²

For specific presentations of dementia, like Alzheimer’s, there are further risk factors, including the cognitive changes that may make a patient forget to eat, or forget if they have eaten already.¹² Alzheimer’s can also impact a person’s sense of smell and bring on social risk-factors for developing eating disorders, including loneliness, isolation, and depression.¹²

Shared risk factors of eating disorders and co-occurring disorders

One reason so many people struggle with eating disorders and a co-occurring disorder is that many of these conditions share several overlapping risk factors, from biological and psychological to environmental and sociocultural causes.

Genetic predisposition

It is possible to be born with the predisposition for developing either an eating disorder, a number of different mental health disorders, or both. 

Many studies have shown at least some degree of heritability for both bulimia nervosa and anorexia nervosa.¹⁴ And a breadth of other work has shown genetic connections to substance use disorder, depression, anxiety, and other mood disorders.

In many of these cases, what gets passed on isn't the disorder itself, but a number of risk factors that may make a person more susceptible to developing the disorder. For example, the way a person reacts to stress—which is often involved in the developing or maintaining of mental health disorders—has been found to be heritable.¹⁴

Other key inheritable risk factors include negative emotionality and harm avoidance, which inform personality traits such as shyness, fearfulness, and a tendency to worry.¹⁴

Serotonin imbalance

Serotonin is an important neurotransmitter which helps with many bodily processes. Capable of boosting feelings of happiness, it's mostly known as a mood stabilizer, but it can also function as an appetite suppressant, creating the sensation of satiety, or feeling full after eating.

Because it plays a key role in both appetite and emotions, it is a common link between eating disorders and comorbid mental health conditions. And several studies have shown that serotonin dysfunction or imbalance may play a role in developing or sustaining several co-occurring eating disorders and mental health conditions.¹⁵

Malnutrition

Regardless of the pattern of a person’s disordered eating, one of the biggest repercussions is an unbalanced diet. And while malnutrition is more of a consequence of eating disorders, rather than a risk factor, it can have a cascading effect on the body that can lead to the development or support of comorbid conditions.

Anxiety and depression, in particular, have been linked to malnutrition, with some studies finding that the absence of certain proteins can promote “anxiety- and depression-like behavior.”¹⁶

Maladaptive emotion regulation strategies

Broadly, emotion regulation refers to someone’s awareness and recognition of their emotional state, as well as any attempt to regulate, or modulate, it. And, whether conscious or subconscious, these mechanisms can play a key part in driving eating disorders and commonly co-occurring conditions.

Indeed, many eating disorders, as well as anxiety and depression, can arise as attempts to cope with unpleasant feelings, especially during the onset of puberty or other times in life that see a number of physiological, psychological, and social changes.² 

Likewise, higher levels of depression or anxiety can lead to the development of disordered eating behaviors as a maladaptive–or harmful–emotion regulation strategy, and vice versa.²

Low self-esteem

Low self-esteem is frequently a major factor in eating disorders and commonly co-occurring mental health conditions. It can drive the development of these disorders, manifest as the result of these disorders, or both.

The trait has been found to play an especially big role in the relationship between eating disorders and depression, contributing to the negative self-perception and poor sense of self-worth that is often a hallmark in both conditions.² But overall, low self-esteem has been found to be a key aspect in many mood disorders and eating disorders.

Perfectionism

Perfectionism is more often associated with anxiety, be it generalized anxiety disorder or more specific manifestations of the condition, such as obsessive-compulsive disorder.

The anxious trait generally manifests as setting and pursuing high standards for oneself, and becoming highly critical of oneself if/when failing to meet those goals.

People struggling with a perfectionist aspect of their anxiety disorder are particularly hard on themselves, often for small, exaggerated, or even imagined transgressions. And this level of sensitivity has been noted as a key maintaining factor in many different eating disorders, anxiety disorders, and, to a lesser extent, depression.²

How to find co-occurring eating disorder treatment

Eating disorders that present with a comorbid mental health condition can cause a number of short- and long-term complications. And the negative effects of these on both mental and physical health tend to get worse with time.

Consulting your primary care physician, therapist, psychiatrist, or another trusted medical professional may be a good place to start. These experts may be able to help you secure an official diagnosis, guide you to successful treatment programs, or otherwise help you determine your next best steps.