Biological factors of anorexia nervosa
Anorexia nervosa (AN) is a very complex illness that has a number of overlapping risk factors. For many years, doctors believed the disorder was sociocultural in origin, stemming from a toxic mixture of social pressure, competition, and the prevalence of unrealistic body images in popular culture, among other factors. (2)
However, advances in genetic research have led to a closer examination of the causes of anorexia, revealing several biological elements that may also play a role.
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Several studies have found anorexia nervosa (and bulimia nervosa) appear to have inheritable traits. (2)
Earlier studies on the subject looked at the prevalence of AN within clusters of biologically related people and found a significant connection, compared to control groups. The reports noted a seven to twelve-fold increase of anorexia nervosa among the related groups—particularly in women. (2)
Still, as families are often raised in similar environments, it was difficult to determine whether nature or nurture was more responsible for this connection. So further studies were carried out to examine anorexia nervosa rates in twins.
Due to their unique genetics, twins typically offer a more nuanced look at whether a disorder stems from biological or environmental factors. The twin studies concluded that anywhere from 58%-76% of the susceptibility to AN in previous studies could be attributed to genes. (2) Other reports, which used different forms of genetic research, have found a wider range of 28%-74%. (3)
Regardless, it’s now widely agreed that biology plays a larger role in the development of AN than previously thought and has been classified as moderately heritable in one study. (2) A number of questions and missing details on the genetic causes of anorexia nervosa remain, however.
Comorbidity describes the simultaneous presence of two or more medical conditions within one person. Anorexia can have a number of existing conditions, including mental health disorders.
The correlation between anxiety disorders and anorexia have been found to be especially strong. Obsessive compulsive personality disorder (OCPD), separation anxiety, and overanxious disorder, as well as phobias and panic disorder have also been found to share some degree of familial transmission and have all been linked to higher rates of anorexia. (2)
Depression can also co-occur with anorexia nervosa. Though not tied as closely to AN as anxiety disorders, major depressive disorder—which is also often inherited—has been considered a relative risk factor for AN. (2)
While these conditions might not necessarily or exclusively be what causes anorexia in a patient, these studies have shown that they can often be connected to the disorder.
Like most other aspects of a person, personality traits can either be inherited, shaped by the environment, or both. A number of more genetically transmissible traits have also been associated with higher rates of anorexia.
In particular, a number of reports have found a prevalence of stress reactivity (or, how a person physiologically reacts to stress), negative emotionality, and harm avoidance in people struggling with anorexia nervosa. (2) these Traits have been found to persist even after a patient’s recovery, leading those studies to conclude these traits may be fixed, and a direct cause of anorexia, contributing to the development of the disorder itself. (2)
Environmental factors of anorexia nervosa
Biology is only one piece of the puzzle. The environment surrounding a person is equally as important in the development of a disorder.
In fact, the cause of anorexia was traditionally attributed almost exclusively to environmental factors. And while an increasing number of biology-focused studies are adding nuance to that idea, it’s still believed many potential causes of anorexia nervosa aren’t biological.
Every person absorbs and reacts to the circumstances of their lives differently. That’s especially true when it comes to something as complex as dealing with an eating disorder. But people struggling with anorexia tend to have similar experiences in their backgrounds.
Trauma of all types is a common occurrence in the lives of people struggling with anorexia, with the disorder’s connection to sexual abuse, physical and emotional abuse, teasing and bullying, divorce, and loss of a family member all documented in a number of studies. (4) In fact, nearly a quarter of all participants in one study were found to fit the official criteria for post-traumatic stress disorder. (4)
Higher risk for developing anorexia nervosa can also be extended across different social groups, ethnicities, and gender identities.
Athletes were found to be significantly more likely than non-athletes to screen for eating disorder behaviors—and less likely to seek treatment for these issues. (5) In a different report, transgender college students were found to be at least four times as likely to experience disordered eating than their cisgender classmates. (6) And several studies have also drawn a link between people struggling with anorexia and people who are autistic. (2)
While white females between 13-19 have historically been the most likely group to be diagnosed with anorexia nervosa, (7,8) the disorder can occur in individuals of all ages, genders, and ethnicities. A number of new reports on the subject are examining the prevalence of AN in people of color, who have historically been underrepresented in most studies.
Social/peer pressure and competition
Peer pressure, family dynamics, and cultural and societal norms are also all considered major environmental causes of anorexia.
Weight-related teasing or critical comments about weight, especially from parents, are both considered potentially triggering scenarios for developing AN. (9) Indeed, parental role modeling has long been studied as a contributing cause of anorexia nervosa, with a string of analyses finding correlation between the eating/dieting habits and weight concerns of mothers and their children. (9)
Of course, this is not always the case. People are sometimes influenced by peers, picking up on a number of less-than-healthy social cues from friends.
Studies looking at social pressure as a cause of anorexia show that people may be both heavily influenced by a peer group that emphasizes the importance of appearanceand intentionally migrate toward these groups. (2, 10) Once embedded, the cultural value of thinness—emphasized in most forms of popular media and often learned by children at a young age—can drive competition within the group, where members will compare weights, diets, and other aspects of appearance and generally create a self-reinforcing echo chamber for these ideals. (10)
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Treatment of anorexia nervosa
While there are a number of independent environmental and biological factors at play, many studies are now concluding that a complex combination of both causes anorexia.
One prevailing theory proposes that a person with a predisposition for eating disorders might intentionally seek out other social groups that put a high value on physical appearance. Another environmental-genetic theory posits that the genes that would lead to developing an eating disorder might present in certain people when they encounter certain societal pressures, such as a weight-focused coach, or other potentially traumatic scenarios. (2)
The distinction is an important one, and may impact the way a person is treated for anorexia. And a number of different therapeutic methods have been used to help people with the disorder.
Cognitive behavioral therapy (CBT) is typically considered the leading therapeutic option for people struggling with anorexia, as numerous studies have found success with the treatment. But CBT is far from the only option for people struggling with anorexia. It just happens to be the subject of more research. Family therapy, art therapy, group therapy, movement therapy, and many more types of therapy can all help, depending on the specifics of the person in need.
Regardless, any course of treatment for the disorder will likely focus on several areas, including: (11)
- Stabilizing weight loss
- Restoring nutrition and physical health
- Addressing the causes behind the disorder
- Learning healthier long-term coping strategies for the identified stressors
Some combination of these therapies has been found to be successful in treating many people struggling with anorexia nervosa. Although the condition can be very dangerous and life-threatening, it’s possible for people to make a full recovery with the right kind of care.
If you think you or someone you know may be experiencing symptoms of anorexia nervosa, Within Health is here to help. We treat eating disorders virtually, through continuous care attuned to our client's needs. Call our admissions team today for more information on getting started.