Is anorexia nervosa an addiction? The short answer is no, anorexia nervosa (AN) is classified as an eating disorder in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5-TR). “Addiction” is often used as a sort of shorthand for substance use disorder (SUD), despite many disorders linked to impaired impulse control sharing many psychological, behavioral and physiological characteristics with SUD.
However, with new information on the neurobiological workings of anorexia nervosa and other eating disorders, surprising similarities between certain eating disorders and behavioral addictions have been observed. So, what is an “addiction”, and does it share similarities with anorexia nervosa?
What is anorexia nervosa?
Anorexia is most often characterized by:
- Low body mass
- Persistent restricted food intake
- Distorted body image
- An intense fear of gaining weight
It can be further broken down into anorexia nervosa bingeing/purging type (AN-BP) and anorexia nervosa restrictive type (AN-R). This is determined by whether the person has engaged in binge-eating or purging in the last 3 months (bingeing/purging type) or not (restrictive type).
What is an addiction?
The issue of what constitutes an “addiction” was a hot topic in recent revisions of the DSM TR-5 and the ICD-11. Previously, in the DSM-IV, there was a chapter on “Substance-Related Disorders”, which has been expanded to “Substance-Related and Addictive Disorders”. This was due to interesting neurobiological information that showed important similarities in substance-related addictions and gambling and gaming disorder (which was previously in the catch-all diagnosis of “Impulse control disorders not otherwise classified”). The debate on when an addictive behavior can be designated its own, unique, diagnosis criteria has been both helped by and made more complex by our increasing understanding of the neurobiology behind these behaviors.
Although anorexia seems to be about restriction and control over behaviors, the case for it being similar to an addiction is the neurobiological response that abstaining from food seems to have. Although neurological research into anorexia and other EDs is still in relative infancy, it is these studies which have led to the conundrum of defining what an “addiction” or “addictive behavior” is and whether anorexia can be called an “addiction” based on these similarities.
Compulsivity as a shared trait in anorexia and addiction
Compulsivity is a trait where, despite adverse consequences, a behavior is persistently repeated. Research suggests that the parallels in symptoms of anorexia and addiction may be linked to this trait. In this study, individuals diagnosed with AN were asked about their experience with the eating disorder. Many felt they had little to no control over behaviors linked to their eating disorder, despite detrimental effects on their physical health, psychological well-being, and social interactions. This is similar to how many people with substance use disorder would describe their relationship with substance misuse. It might be too simplistic to place all the similarities between anorexia and addiction under the umbrella term “compulsivity”, but this conceptualization has given researchers a good indication of their shared neurobiology.
The shared neurobiology of anorexia and addiction
One of the more compelling reasons to label anorexia as an addiction stems from the common brain pathways, structures and neurotransmitters that these mental health disorders appear to share. While by no means an exhaustive list, here are some examples of the neurobiological similarities studies have shown are shared by anorexia and addiction:
Dopamine
Brain pathways using the neurotransmitter dopamine seem to be the main way that humans and other animals motivate themselves to explore and seek rewards. If a behavior results in the brain’s release of dopamine, we are more likely to repeat it. In states of starvation and extremely low body weight (such as in anorexia) the release of dopamine increases in areas of the brain, such as the nucleus accumbens. This may trigger a “reward” response for not eating and encourage food restriction, much like the release of dopamine when taking certain drugs can lead to drug misuse.
Serotonin
Serotonin levels also play an important role in eating behaviors. Serotonin levels in the nucleus accumbens have been shown to influence how soon individuals feel “full” or satiated and how proactively they seek food after periods of food restriction. By increasing serotonin release in the nucleus accumbens of rats using ecstasy (MDMA), researchers found that the rats ate less and sometimes not at all. While this explains how some drugs (like cocaine and amphetamines) suppress appetite and can lead to anorexia developing alongside SUD, the study showed something really interesting that may explain why only a small part of the population develops anorexia.
Some of the rats in the study had the gene for specific serotonin receptors in the nucleus accumbens turned off. These were the only rats that didn’t resume eating at heightened rates after food restrictions were removed. This study suggests one reason that some individuals might be able to maintain food restriction for long enough to develop anorexia is if they are part of the small group that is both “missing” this gene and who underwent food deprivation for a long period of time. This assertion is based on rat studies for now, but it is an interesting lead in understanding the link between genes, the brain and anorexia. Genetic influence for susceptibility to anorexia and resistance to treatment highlights that blaming individuals for this mental illness is not helpful and may increase stress, decrease food intake and can lead to a perpetuating cycle.
Decision-making pathways in the brain
The orbitofrontal cortex is an area at the front of the brain, close to the eyes, that deals with making complex decisions. It is close to the areas of the brain that are linked to emotion and some sensations (like smell, taste and texture) and is the hub where all of this information is interpreted and translated for use in future decision-making. Associations with food as being pleasurable or eliciting certain emotions can play a role in food intake.
The interconnectedness of these pathways could explain how being overwhelmed by food’s tastes, smells, and textures, plus the strong, negative emotional responses associated with food, eating or gaining weight, could link to the rationale behind restricting food intake and the development and maintenance of anorexia. Conversely, the pleasurable associations with the emotional or sensory effects of certain substances or addictive behaviors may lead to the decision to misuse these and the subsequent development of an addiction.
The illusion of “choice” and the blame that accompanies this are barriers to treatment in both anorexia and addiction. Although both may appear as a “choice” or conscious “decision”, much of the rationale behind these behaviors is provided by brain regions that are not directly controlled by the individual. While different disorders, both anorexia and addiction involve similar regions of the brain, similar neurotransmitters and similar neural pathways.
Could anorexia be considered an addiction?
The complexity involved in the processes of determining whether to consistently perform a behavior that is overtly unhealthy underlies the difficulties in treatment of both anorexia and substance use disorder (SUD). It was the neurobiological and physiological similarities shared by substance use disorder and gambling or gaming addiction that led to their grouping in the DSM-5-TR. This is the main reason that it is so tempting to see anorexia as an addiction.
However, anorexia is a disorder that is defined by more than shared neurobiology. Anorexia nervosa has distinctly unique symptoms, causes, risk factors and treatment plans from addiction as well as being seen in different demographics, who don’t always overlap. To treat one as you would the other would be unethical and potentially disastrous.
Ultimately, anorexia nervosa is seen as a completely different diagnosis than addictions. However, AN has the highest mortality rate of any psychiatric disorder and there is an ongoing search for effective ways to treat this life-threatening disorder. Researching similarities between anorexia nervosa and addiction or other disorders – like obsessive-compulsive disorder (OCD) – may help in finding effective treatments for similar symptoms. While anorexia may not be an addiction, the shared characteristics can help us to better understand both disorders.
